Herein we assess the progress of efforts to reestablish Mexican wolves (Canis lupus baileyi) in the Blue Range Wolf Recovery Area (BRWRA). This review is a direct result of an Environmental Impact Statement (EIS) concluded by the U.S. Fish and Wildlife Service (USFWS) in 1996 (U.S. Fish and Wildlife Service 1996). The EIS and associated final rule call for the USFWS to reestablish Mexican wolves to the BRWRA. The recovery area encompasses 17,752 km2 (6,854 mi2) of the Apache National Forest in southeastern Arizona and the Gila National Forest in southwestern New Mexico.
Specifically, the U.S. Department of Interior has authorized the USFWS to reintroduce about 15 wolves every year for 3 to 5 years in the BRWRA primary recovery zone. The primary recovery zone comprises about 2,664 km2 (1,029 mi2) of the Apache National Forest). The remainder of the Apache National Forest and all the Gila National Forest make up the secondary recovery zone. The USFWS may conduct re-releases in the secondary recovery zone and wolves that move from the primary recovery zone can inhabit the secondary zone. The USFWS began reintroductions with the release of 11 wolves in March 1998. From then until March 2001 the USFWS released another 45 individuals on 61 occasions....The final rule governing the reintroduction project and the 1998 Mexican Wolf Interagency Management Plan both require the USFWS to conduct a comprehensive review of the project at the end of the third year (i.e., March 2001). The full evaluation must include recommendations regarding continuation, modification, or cancellation of the reintroduction effort. If appropriate, the evaluation may include recommendations on whether and how to use the White Sands Wolf Recovery Area.
....The USFWS contacted the Conservation Breeding Specialist Group (CBSG) to conduct the specified review. CBSG is ideally suited for the task because of extensive worldwide experience with small population restoration, conservation, and management. On behalf of CBSG, Paul Paquet assembled an expert review team composed of John Vucetich, Michael Philips, and Leah Vucetich. The team review is based on data provided by the USFWS data collected in the first 3 years of the reintroduction project.
2. ISSUES FOR WHICH ASSESSMENTS WERE REQUESTED
Our assessment addresses the following questions as outlined by the 1998 Mexican Wolf
Interagency Management Plan.
Have wolves successfully established home ranges within the designated wolf recovery
Have reintroduced wolves reproduced successfully in the wild?
Is wolf mortality substantially higher than projected in the EIS?
Is population substantially growth lower than projected in the EIS?
Are numbers and vulnerability of prey are adequate to support wolves?
Is the livestock depredation control program effective?
Have documented cases of threats to human safety occurred?
We were not asked to address the following 2 additional questions identified in the 1998
Mexican Wolf Interagency Management Plan:
Is effective cooperation occurring with other agencies and the public?
Are combined agency funds and staff adequate to carry out needed management, monitoring
....4. ECOLOGICAL BACKGROUND
....Wolves evolved in environments that included prevailing disturbance regimes with certain ecological characteristics and boundary conditions. Disturbance varied in frequency, duration, extent, and intensity, thereby resulting in different spatio-temporal patterns of change. Behaviors and life history traits conferred resilience that enabled wolves to absorb these intrinsic disturbances and persist. Modern humans, however, have presented new regimes of disturbance that could be considered exotic because they are qualitatively novel or quantitatively atypical. Three mechanisms of resilience at different hierarchical levels are: individual - plasticity in foraging behavior that ameliorates flux in food availability; population - demographic compensation that mitigates increased exploitation; and metapopulation dispersal - that provides functional connectivity among fragmented populations. Accordingly, flexible food habits, high annual productivity, and dispersal capabilities enable wolves to respond to natural and human-induced disturbances. However, environmental disturbances at various temporal and spatial scales may exceed the ability of wolves and systems that support them to absorb disturbance.
Wolves display remarkable behavioral plasticity in using different prey and habitats. They are able to substitute one resource for another in the face of environmental disturbance. Specifically, wolves specialize on vulnerable individuals of large prey [elk (Cervus elaphus) and moose (Alces alces)] yet readily generalize to common prey [usually deer (Odocoileus sp.)].
Wolf populations are able to compensate demographically for excessive mortality. Under certain circumstances this compensation enables wolves to respond to increased rates of juvenile or adult mortality with increased reproduction and/or survival, thereby mitigating demographic fluctuations. Dominant wolves are able to reproduce at a very young age and usually reproduce every year thereafter. Age at reproductive senescence has not been well documented but few females survive to reproduce past age 9. Wolves also display remarkable ability to recover from exploitation. For example, during a wolf reduction program in the Yukon, wolves recovered to pre-reduction densities within 5 years. Wolves immigrated into the study area during early recovery, followed by increases in pack size from reproduction.
The final mechanism that confers resilience to wolf populations is dispersal. When dispersal is successful, vanishing local populations are rescued from extirpation and functional connectivity of metapopulations is established. Wolves have tremendous dispersal capabilities and as a result, connectivity of populations can be high. Dispersing wolves typically establish territories or join packs within 50-100 km of the pack in which they were born. Some wolves, however, move longer distances. For example, Fritts (1983) observed a wolf that traveled at least 917 km.
b. THE PERILS OF SMALL POPULATIONS
Small populations, because of random normal variability in demographics, are more likely to become extinct than larger populations. Moreover, these small populations are thought to be vulnerable because of deleterious effects of inbreeding and chance environmental disturbances such as forest fires, disease or infestations that affect a species or its prey. In theory, the interaction of these factors increases the probability of extinction. Small insular populations may have a restriction of genetic variation because they represent a very small subset of the total population (i.e., a few individuals). As populations become smaller a further reduction in genetic variation results in decreased survival (i.e., increased mortality). Increased mortality leads to additional reduction in genetic variation resulting in an "extinction vortex." Biologists theorize that because of this self-amplifying cycle the rate of extinction for small populations is higher than predicted from the population size alone
c. USE OF HABITAT AND PATTERNS OF TRAVEL
Throughout its broad geographical distribution the gray wolf is considered an ecosystem and prey generalist. However, populations are adapted to local conditions and are, therefore, specialized concerning den site use, foraging habitats, and prey selection. In mountain regions, the effects of physiography, weather, prey distribution, and prey abundance combine to concentrate activities of wolves into forested valley bottoms. Elevation can also govern seasonal movements of wolves. In mountainous areas with high snowfall, use of low elevation valleys increases during winter, where frozen rivers and lakes, shorelines, and ridges are preferred because of ease of travel. Ski trails, snowmobile trails, graded roads, and packed roads can artificially enhance the range and efficiency of winter forays. Singleton (1995) has suggested that variation in pack size, variation in home range size, and interactions with sympatric predators may influence habitat use and travel patterns. He further speculated that turning frequency or travel route complexity are likely to vary depending on whether an animal is within a patch of concentrated resource availability (e.g., deer winter ranges), moving between known patches, or exploring new areas.
d. INFLUENCE OF WOLVES ON THE BIOLOGICAL COMMUNITY
Generally we understand that the ecology of predators, prey, and scavengers, is intertwined. However, the details of these relationships, and the general role of predation in shaping the structure of ecological communities is poorly understood. Changes in predator-prey relationships may affect species other than wolves and their prey. Disruption of top predators can affect interspecific associations by disrupting relationships within food webs. This, in turn, may cause unanticipated ripple effects in populations of other species, which markedly alter the diversity and composition of a community (Paine 1966). Multi species effects often occur when changes in a third species mediate the effect of one species on a second species (or analogous higher-order interactions).
For example, a wolf can affect a grizzly bear (Ursus arctos) by reducing the availability of a limiting resource (possibly an ungulate). Also a secondary carnivore such as a coyote (C. latrans) can affect the degree to which a herbivore's lifestyle is influenced by a primary carnivore such as a wolf. Ecologists have only begun to develop theory that attempts to explain the coexistence of prey in terms of predator-influenced niches ("enemy-free space"). Terborgh and Winter (1980) noted that we know little about the loss of top carnivores in
terrestrial environments, and predicted a wave of extinctions following the loss of any key species. For example, if species interact as competitors, as predator and prey, or as facilitators in successional processes, then the presence of one species may influence the extinction probability of another "linked" species.
Recent evidence suggests the importance of cascading trophic interactions on terrestrial ecosystem function and processes. Research has documented differences within systems from which large predators have been removed or are missing. Accordingly, the ecosystem impacts of wolves may be more profound than previously expected. For example, on Isle Royale, Michigan wolf predation on moose has been shown to influence positively biomass production in trees of boreal forest. Growth rates of balsam fir (Abies balsamea) were regulated by moose (Alces alces) density, which in turn was controlled by wolf predation. When the wolf population declined for any reason, moose reached high densities and suppressed fir growth. This top-down "trophic cascade" regulation is apparently replaced by bottom-up influences only when stand-replacing disturbances such as fire or large windstorms occur at times when moose density is already low. This is strong evidence of top-down control of a food chain by wolves....
In addition to the obvious interactions between wolves and prey, wolves provide a regular supply of carrion to scavengers. Less obvious community dynamics might include the relationships between different predators, and how wolves influence these relationships. For example, how do wolves modify the relationships between coyotes and foxes' Interest in the role of wolves in the broader ecosystem is not new. From 1939-1944 Adolf
Murie (1944) conducted field studies in Denali Park Alaska to determine "...the ecological picture centering about the wolf of Mount McKinley National Park". Here, he entertained questions about the relationships between park wolves and other wolves, between wolves and their prey, and between wolves and other predators. Few studies, however, are available to yield insights into many of the relationships between wolves and other ecosystem components.
e. RESPONSE OF WOLVES TO HUMAN ACTIVITIES
The seriousness of human disturbance is ultimately a human judgement and, as such, some may consider any alteration of the normal activities of wolves to be undesirable. The ecological issue is how the probability of persistence changes with habitat degradation, small population size, and population isolation. The management issue is what probability of persistence and environmental quality is compatible with legislation and acceptable to society. Interpretation of the wolf-human interaction is confounded by multiple factors that influence how wolves use the landscape and react to people. Because of the wolf's inherent behavioural variability, it is unlikely that all wolves react equally to human induced change. Moreover, many extraneous
factors contribute to variance in behaviour of individual wolves. Because we have developed no reasonable expression of those differences, assessments are usually applied at the pack and population levels.
The specific conditions in which wolves are 'disturbed' (i.e., distribution, movements, survival, or fecundity are impaired) are believed to be highly variable. The extent and intensity of disturbance appear to vary with environmental and social context, and the individual animal. Though wolves are sensitive to human predation and harassment, we have limited empirical information on tolerance to indirect human disturbance. Several
studies suggest the main factor limiting wolves where they are present and tolerated by humans is adequate prey density. Although human activities have been shown to influence the distribution and survival of wolves,
human-caused mortality is consistently cited as the major cause of displacement.
Studies that have quantified wolf/human interactions have shown wolves avoid humans or are displaced via human induced mortality. Avoidance is temporal and spatial. Several studies that used road densities as an index of human influence concluded that human activities associated with roads affect the survival and behaviour of wolves. Interpretation, however, was confounded because many human activities associated with roads result in the death of wolves....A study in Alaska concluded that wolves avoid heavily used roads and areas inhabited by humans, despite low human caused wolf mortality....
Recent reports suggest wolves in Minnesota tolerate higher levels of disturbance than previously thought possible. Wolves, for example, are now occupying ranges formerly assumed to be marginal because of prohibitive road densities and high human populations. Legal protection and changing human attitudes are cited as the critical factor in the wolf's ability to use areas that have not been wolf-habitat for decades. If wolves are not killed, they seem able to occupy areas of greater human activity than previously assumed.
....Nonetheless, wolves in Minnesota continue to avoid populated areas, occurring most often where road density and human population are low. Moreover, the fact that wolves are using areas of greater human activity suggests dispersers or marginalised individuals are being pushed into suboptimal habitat. More suitable and safe habitat may be saturated by dominant animals or packs. This supports the idea that wolves occupy habitat closer to humans only if necessary. A similar phenomenon has been shown in grizzly bears and many avian species.
....The observed patterns of displacement suggest the presence of humans repulses wolves, although a strong attraction to highly preferred habitats increases a wolf's tolerance for disturbance. As conditions become less favorable, the quality of habitat likely takes on greater importance. Tolerance thresholds are unknown but...changes in patterns of habitat use were evident when human activity exceeded 100 people/month. Nearly complete alienation of wolves occurred when more than 10,000 people/month used an area.
f. HUMAN INFLUENCE ON HABITAT USE BY WOLVES
The degree of human influence probably varies according to the environmental context. If a particular habitat is highly attractive, wolves appear willing to risk exposure to humans, at least within some limits. As levels of disturbance increase, favorableness of habitat likely takes on greater importance. For example, we know that wolves select home sites near intense human activity when denning areas are limited, or where innocuous human activity occurs. The presence of artificial food sources (e.g., carrion pits, garbage dumps) also attracts wolves and reduces avoidance of human activity. In the Bow River Valley, wolves denned within 500 m of the Trans-Canada highway when Parks Canada was dumping carrion in the area. Wolves abandoned the home site after Parks stopped dumping of the carrion.
....The major impacts of human induced changes are, in order of decreasing importance, physical loss of habitat, loss of prey species, fragmentation of habitat, isolation of habitat, alienation of habitat, alteration of habitat, changes in original ratios of habitat, and changes in juxtaposition of habitats. These effects combine to have local and population level influences by altering the composition of biological communities upon which wolves are dependent, restricting movements, reducing foraging opportunities, and limiting access to prey. Obstructing movements also increases the vulnerability of wolves to other disturbances as they attempt to learn new travel routes.
Indirect human influences can affect an animal's chance to survive and reproduce. As wolves approach their limits of tolerance, they become increasingly susceptible to what would otherwise be minor influences. In the mountainous terrain, natural landforms and the condensed arrangement of habitats make wolves highly susceptible to the adverse effects of human disturbance. Because most development occurs in areas preferred by wolves, human activities unavoidably increase the risk of death and injury for wolves, decrease opportunities for wolves to move freely about, displace or alienates wolves from preferred ranges, and interrupt normal periods of activity. In less physiographically complex environments multiple travel routes link blocks of wolf habitat. Destruction or degradation of one or 2 routes is not usually critical, because safe alternative routes are available. In contrast, wolves living in mountains cannot avoid valley bottoms or use other travel routes without affecting their fitness. Therefore, tolerance of disturbance is probably lower than in other human dominated environments where wolves can avoid disturbed sites without seriously jeopardizing survival.
g. RESPONSE OF WOLVES TO LINEAR DEVELOPMENTS
The security of wolf populations in the many regions may be tenuous, because linear developments heavily dissect wolf ranges (i.e., highways, secondary roads, railways, and power line corridors). Highway mortality has become a primary cause of wolf mortality and there is accumulating evidence of habitat loss, fragmentation, and degradation related to roads. Ensured connectivity of quality habitats is important for survival of large carnivores, especially for those that face a high risk of mortality from humans or vehicles when travelling across settled landscapes.
....Besides fragmenting and consuming critical habitat, linear developments provide access to remote regions, which allows humans to deliberately, accidentally, or incidentally kill wolves. Despite legal protection, 80% of known wolf mortality in a Minnesota study was human-caused (30% shot, 12% snared, 11% hit by vehicles, 6% killed by government trappers, and 21% killed by humans in some undetermined
manner). Mech (1989) reported 60% of human-caused mortality in a roaded area (even after full protection), whereas human caused mortality was absent in an adjoining region without roads. On the east side of the Central Rockies between 1986 and 1993, human caused mortality was 95% of known wolf death. Thirty-six percent (36%) of mortality was related to roads.
....The response of wolves to different road types and human presence at the boundaries of Kenai National Wildlife Refuge, Alaska, was examined in a study of radio-collared wolves. Wolves avoided oilfield access roads open to public use, yet were attracted to a gated pipeline access road and secondary gravel roads with limited human use. Thurber et al. speculated that roads with low human activity provide easy travel corridors for wolves. The response of wolves to a major public highway was equivocal. They thought wolf absence from settled areas and some roads were caused by behavioral avoidance rather than direct attrition resulting from killing of animals....
5. HAVE WOLVES SUCCESSFULLY ESTABLISHED HOME RANGES
WITHIN THE DESIGNATED WOLF RECOVERY AREA?
Biologists usually define the home range of a wolf as an area within which it can meet all of its annual biological requirements. Seasonal feeding habitat, thermal and security needs, travel, denning, the bearing and raising of young, are all essential life requirements. The manner in which habitats for these requirements are used and distributed influences home range size and local and regional population distributions. Generally, wolves locate their home ranges in areas where adequate prey are available and human disturbance minimal. Wolves use areas within those home ranges in ways that maximize encounters with prey.
Newly colonizing wolf pack might shift home ranges in response to climate, food availability, human disturbance, and other factors. A colonizing pack might have a larger, more fluid, home range than a pack surrounded by other wolf packs. Some evidence suggests that wolf packs colonize areas that were first "pioneered" by dispersing lone wolves....
b. DATA SUMMARY
We assessed home ranges using locations from radio-collared animals....These data include all telemetry locations from 3 March 1998 to 3 March 2001. Each location was appended by wolf identification, date, time, and pack membership. Although locations were qualitatively ranked for accuracy, no quantitative assessment of telemetry error was available....
Our objective was to quantitatively describe areal distribution of reintroduced Mexican wolves within the recovery region. In a few cases, however, subjective determination of the home range was more appropriate.... Locations of individual wolves were grouped by pack affiliation. We defined a pack as 2 or more wolves that traveled together more than 1 month. For each pack we used one wolf/year to represent the annual home range of the pack. This is a reasonable assumption if a high degree of association exists between pack members. We confirmed pack affiliations by examining telemetry locations of wolves believed to be associating and through visual observations of the wolves by the field crew....
From 1998 through 2001, 9 wolf packs were identified by name in the telemetry database. However, the criteria for specifying packs were not always biological. Release sites, geographic locations, and affiliations with other wolves influenced pack designation. Packs, pack compositions, and configurations of home ranges changed as reintroduced wolves encountered other wolves, and established new territories. In addition, the frequent removal and reintroduction of wolves confounded the assignment of individual wolves to specific packs.
The number of recorded aerial and ground locations varied among wolf packs. For the most part, the frequency of locations reflected the time that radio collared wolves were free-ranging, rather than differential effort by the field crew. Time of year, however, affected the number of locations acquired. Discussions with the field team confirmed that for logistic reasons they reduced monitoring activities in winter. We identified some locations that were far outside the reintroduction area. Many of these were recording or data entry errors. Several, however, were from wandering or dispersing wolves.
....Many individuals and packs showed home range fidelity typical of wolves with established territories. However, frequent social disruption via mortality, recaptures, and re-releases may have altered the natural territorial behavior of packs. Wolves are long-lived social carnivores that transmit information between generations and among individual pack members. In this regard, the establishment, location, and maintenance of home ranges likely depend on a stable pack structure and the persistence of traditional pack knowledge. The home range behavior of reintroduced wolves may be highly susceptible to social disruption because they lack a cognitive map of the area. Moreover, lack of familiarity with the landscape may have a
stronger influence on captive reared animals than wild born.
We conclude that some wolves have successfully established home ranges and possibly pack territories within the designated wolf recovery area. We caution, however, that frequent recaptures and re-releases confounded our analysis. These manipulations may also be interfering with pack formation and establishment and maintenance of home ranges. Lastly, individual wolves have shown some indication of dispersing outside the recovery area. This is to be expected and required if the regional population is to be viable.
6. HAVE REINTRODUCED WOLVES REPRODUCED SUCCESSFULLY IN THE WILD?
i. Births versus recruitment
(1) Compared with adults, pups have relatively low survival rates during the first year of life.
(2) In a sense, pups do not really contribute to the viability of a population until they have survived a period of high mortality rate associated with being a pup.
(3) Although the EIS refers to projected numbers of pups, the projections seem to treat pups as though they have been recruited into the adult population (i.e., with survival rates like adults).
b. DATA SUMMARY
....Dense vegetation and the secretive nature of wolves precluded regular and accurate visuals of wolves.
Consequently, the Interagency Field Team did not routinely observe wolves during spring and summer when pups are easiest to distinguish from adults. We assumed the presence of dens and rendezvous sites when movements became localized in April through July or when lactating females or pups were captured. Sometimes, ground checks confirmed potential denning and rendezvous areas.
We determined natality directly from field observations of dens, rendezvous sites (pup rearing and resting areas), and packs. We ascertained successful year-specific reproduction using changes in pack size from March to the following December. We assumed unsuccessful reproduction (i.e., no or failed reproduction) when a pack did not display focal activities in the summer. Annual recruitment was derived from winter pack sizes recorded in February.
Births have taken place in the wild. Births and recruitment rates, however are lower than projected in the EIS.
The number of free-ranging Mexican wolves at the end of third year is similar to that projected in the EIS. Survival and recruitment rates, however are far too low to ensure population growth or persistence. Without dramatic improvement in theses vital rates, the wolf population will fall short of predictions for upcoming years.
7. IS WOLF MORTALITY SUBSTANTIALLY HIGHER THAN PROJECTED IN THE EIS?
Researchers do not agree on the annual rate of mortality that causes a population decline in wolves. However, Keith (1983) and Fuller (1989) reviewed several wolf studies across North America and concluded that harvests exceeding 28-30% of fall populations resulted in declines....Various researchers have suggested different rates of annual mortality they believe control growth of wolf populations. However, the annual rate of mortality that causes a population decline in wolves is unknown. Furthermore, many researchers consider only harvest (hunting or trapping) when they calculate mortality rates that cause wolf population declines. For instance Mech (1970) concluded an annual harvest of 50% or more was necessary to control wolf populations based on pup-adult ratios but did not distinguish between harvest and natural mortality. Keith (1983) reviewed studies of 13 exploited populations and determined that harvests exceeding 30% of fall populations resulted in population declines. Similarly Fuller (1989) found annual rates of wolf increase vary in direct response to rates of mortality and where humans kill wolves, harvests exceeding 28% of autumn or early winter populations might result in a population decline. He concluded a population would stabilize with an overall rate of annual mortality of 0.35 or rate of human-caused mortality of 0.28. Consequently, the exact relationship between the annual rate of mortality from all human causes (harvest, collisions with cars and trains) and population limitation or decline in wolves is uncertain.
In areas where ungulate biomass is low, researchers have noted that starvation and intraspecific aggression are common. For instance, in southwestern Quebec, Messier (1985a) noted wolves with fewer prey available incurred more deaths from natural causes, namely starvation and intraspecific aggression. Similarly, Mech (1977a) noted occurrence of starvation and intraspecific aggression increased as prey availability declined in Minnesota. Disease cannot be linked with certainty to low availability of food but the relationship makes sense intuitively. A population of wolves lacking food should be more vulnerable to disease than one with more food available. Furthermore, food shortage leading to nutritional stress could combine with disease factors to increase the significance of otherwise innocuous or sub-lethal conditions.
In most studies, no disease-related mortality has been reported. In other studies, from 2-21% of wolf
mortality has been attributed to disease. Ballard et al. (1997) concluded that occurrence of rabies was a significant factor in a decline of wolves from Alaska. In that study, rabies-caused mortality was 21%.
Quantifying the importance of food in limiting population growth based on cause of death alone is difficult. In the literature, results vary among studies. On Isle Royale, annual mortality from starvation and intraspecific strife (both related to low food availability) ranged from 18-57% during a 20-year period....
Human-caused mortality can also be an important limiting factor. However, quantifying the importance of human-caused mortality as a limiting factor is difficult. These causes include legal harvest, illegal harvest, vehicles on highways, and trains.
b. DATA SUMMARY
We used information recorded in the telemetry and events databases. All free-ranging Mexican wolves were radio-collared from time of release. Moreover, each radio-collared Mexican wolf was and continues to be relocated regularly and frequently via ground and aerial telemetry. Frequent monitoring reveals whether each wolf is alive or dead at the time of relocation.
We were not able to address the question of annual mortality directly because removals and re-releases precluded calculating annual rates of mortality. Thus, we estimated survival rates for the Mexican wolf population and then compared these estimated values with the survival rates projected in the EIS. Survival rate is the chance (or probability) of surviving some specified time. Survival rates are typically expressed as values between zero and one. For example, if the annual survival rate of an individual is 0.82, we would say that individual has an 82% chance of surviving during the next year. Survival is a critical population process and estimating survival rates is an important part of measuring viability of populations. Management of protected wolf populations requires quantitative survival measurements to identify factors that drive population
change. From the survival rate one can also understand the mortality rate. The mortality rate of an individual or population is one minus the survival rate.
....From the perspective of a free-ranging population, returning a wolf to captivity (from now on, recapture event) is equivalent to a mortality event. Thus, we conducted 2 survival analyses. One analysis considered only true biological deaths, and the other treated biological deaths and recapture events as mortality events. In both analyses, we reincluded wolves from time of release until "mortality" or disappearance of the radio-signal occurred.
....The starting date of the survival study was March 1998 and the end date was March 2001....
Forty-seven (47) wolves were monitored From March 1998 (when Mexican wolves were first released) to March 2001. Twenty-three (23) wolves are currently being monitored. Four (4) wolves are unaccounted for. Twenty (20) wolves were recaptured following release. Nine (9) of these were re-released and are known to be alive. Two (2) wolves were re-released but contact was lost and their fate is unknown. One of the re-released wolves died. Eight (8) of the recaptured wolves were not re-released and some died in captivity. Seventeen (17) wolves are known to have died, 10 in the wild. Human caused mortality was the most common cause of death. Of the human related deaths, most were caused by gunshots. Wolves also died from distemper and parvovirus. Both these diseases are contracted or originally spread from domestic animals. Death by disease was higher than projected in the EIS.
When recaptures were included as mortalities, survival rates were lower than projected in the EIS. Excluding recaptures as mortalities resulted in survival rates exceeding the EIS projections in 1999 and 2000. Survival rates from either method, however, were lower than for wolves in the Flathead region of Montana and British Columbia, lower than for wolves in the central Canadian Rocky Mountains, lower than a recovering wolf population in the Yukon, and higher than an exploited population in Alaska.
Frequent removals and re-releases of wolves confounded our analysis of rates and causes of mortality. However, if recaptured wolves were at high risk of being killed, then survival is much lower than projected in the EIS. Human-related deaths were the greatest source of mortality for reintroduced Mexican wolves. Shooting was the major source of death. Numerous other studies have reported human-caused deaths as the major cause of wolf mortality.
8. IS POPULATION GROWTH SUBSTANTIALLY LOWER THAN PROJECTED IN THE EIS?
Rates of increase in wild wolf populations have varied between 0.93 and 2.40. Several factors limit growth of wolf populations; those reported most commonly include ungulate biomass and human-caused mortality.... Keith (1983) suggested the amount of food available and age structure of the population affect rates of growth of wolf populations. VanBallenberghe (1981), Gasaway et al. (1983), Keith (1983), Peterson et al. (1984), Ballard et al. (1987), and Fuller (1989) found that wolf populations can be limited by harvest levels of 20-40%, but that the lower rate has a more significant effect in an area with low ungulate biomass. Another factor to
consider is that effects of harvest vary with time and population structure. If productivity is high, and consequently the ratio of pups to adults is high, the population can withstand a higher overall mortality because pups (non-producers) make up a disproportionate amount of the harvest. Furthermore, net immigration or emigration may mitigate the effects of harvest.
b. DATA SUMMARY
We assessed the density of the wolf population, size of established packs, and population growth using radiotelemetry data and direct observation by the Interagency Field Team....
We calculated density of wolves/1000 km2 by determining intra-pack densities (home range size/number of wolves in pack) of radio-collared wolves and averaging these densities per year. The size of packs was based on numbers of wolves observed during midwinter aerial locations (15 Jan-15 Feb). We estimated population growth using finite rates of increase (8) based on the ratio of successive yearly estimates of density....
From available databases and discussions with the Interagency Field Team, we identified a number of events relevant to assessment of population dynamics. Using this information, we calculated population growth rates and the varying number of free-ranging wolves over time. Growth rates and numbers of wolves were close to projections, although frequent re-releases and removals obscured comparisons. To provide context for interpreting these results, we also generated mean growth rates for other reintroduced and recovering wolf populations. To date, the growth rate of the reintroduced Mexican wolf population is comparable with similar reintroduction and recovery efforts. Assessing the average growth rate only tells part of the story. Fluctuations in growth rates are also critical. The more fluctuation the greater the extinction risk....
To date, intervention has dominated natural processes. So, determining if the growth rate is lower than predicted in the EIS is not possible. If the current rate of intervention continues, restoration of a population of 100 wolves would require 28 re-releases annually and 41 removals annually. Although the current population size is similar to that projected in the EIS, we suspect that population growth would have fallen far short of expectations without intervention. Clearly, managers must balance future introductions, recaptures, and re-releases with the need to establish and maintain natural population processes....
9. ARE NUMBERS AND VULNERABILITY OF PREY ADEQUATE TO SUPPORT WOLVES?
Without human disturbance, densities reflect the wolf's dependency on ungulate prey species. Wolf population dynamics are believed to be largely dictated by the per capita amount of prey and its vulnerability to predation, and the degree of human exploitation. The effect of food on wolf demography is mediated by social factors, including pack formation, territorial behavior, exclusive breeding, deferred reproduction,
intraspecific aggression, dispersal, and by primary prey shifts. Wolf populations are closely linked to population levels of their ungulate prey. Maintaining viable, well-distributed wolf populations depends on maintaining an abundant, available, and stable ungulate population. Packard and Mech (1980) concluded that intrinsic social factors and the influence of food supply are interrelated in determining population levels of wolves. In situations where other factors reduce prey populations (e.g., winter weather), predation by wolves can inhibit the recovery of prey populations for long periods. In a multiprey system, the stability, or equilibrium, of ungulate prey and wolf populations seems to depend on a variety of factors, including the wolf predation rate, the number of ungulates killed by hunters, the ratio of ungulates to wolves, and the population growth rate of different ungulate species.
Changes in habitat composition and distribution can have a significant effect on prey densities and distributions, and therefore wolf spatial distribution. Wolf packs may react to changing conditions in varying ways, depending on the location of their territories in relation to other packs and prey distribution. If packs have lower prey densities within their territories, they may exploit territories more intensely. This may be achieved by 1) persevering in each attack, 2) using carcasses thoroughly, 3) feeding on alternative and possibly second-choice food resources such as beaver (Castor canadensis), and 4) patrolling their territory
more intensely. Messier, in his study area in southeastern Quebec, found daily distances of Low Prey packs were on average either greater (summer) or equal (winter) to daily distances of High Prey packs. The territory size, however, was approximately 35% smaller in the Low Prey area, supporting the fact that wolves were searching each unit area with greater intensity in both seasons.
Many studies emphasize the direct effects (e.g., prey mortality) wolves have on the population dynamics of their ungulate prey. However, predation can also profoundly affect the behaviour of prey, including use of habitat, time of activity, foraging mode, diet, mating systems, and life histories. Accordingly, several studies describe the influence wolves have on movements, distribution, and habitat selection of caribou (Rangifer tarandus), moose, and white-tailed deer. Wolves can increase the rate at which they accrue resources by seeking out areas with dense concentrations of prey. Prey, in turn, can lower their expected mortality rate by preferentially residing in areas with few or no wolves....
Unusually mild or severe winter weather can result in ungulate populations that are temporarily higher or lower than predicted habitat capability (which reflects long-term average maximum). Where predation is a factor, ungulates may exist at levels well below carrying capacity for relatively long periods. The interactions of ungulates and their predators (in our case wolves, coyotes, foxes, black bears, and cougars) may, under some circumstances, overshadow habitat capability as a controlling factor for ungulate populations. Ungulate populations may be more strongly influenced by the frequency and depth of population lows, than by habitat capability. Ungulate biomass can affect rates of population increase and resulting densities of wolves.
Building on work of Keith (1983), Fuller (1989) reviewed 25 studies of North American wolf and prey populations and found rates of increase of wolf populations are most affected by relative availability of ungulate biomass (directly influencing survival of pups <6 months old) and human-caused mortality. He concluded that regardless of prey type or stability of wolf populations, average wolf densities are clearly correlated with the biomass of ungulates available per wolf. Furthermore, he found the index of ungulate biomass per wolf is highest for heavily exploited or newly protected wolf populations and lowest for unexploited wolf populations or those where ungulates are heavily harvested.
b. DATA SUMMARY
We used information in the carcasses database to assess wolf use of prey species....
We estimated potential wolf numbers using regression equations that relate wolf numbers to ungulate biomass. The equations were modified to reflect prey species available to wolves in Arizona and New Mexico. Accordingly, biomass was calculated by multiplying population densities of elk, white-tailed deer, and mule deer (O. hemionus) by average edible weights of elk, white-tailed deer, and mule deer....Assuming that ungulate populations would decline slightly in the presence of wolf predation, prey densities were reduced 10% in our final calculations. We assumed prey were evenly distributed and equally available throughout the primary and secondary release sites. Bighorn Sheep (Ovis canadensis), pronghorn (Antilocapra americana, javelina (Tayassu tayacu), and beaver (Castor canadensis) were not included in our analyses because no
population data were available.
The Interagency Field Team recorded 55 probable wolf kills. Elk constituted 85%, mule deer 7%, and deer of unknown species about 4% of recorded kills. The predominance of elk in the diet was consistent among packs. Based on numbers of prey available and biomass available within the primary release site, elk were used disproportionately. Note, however, that observational bias may skew collection of kill data. Elk are easier to find because they are larger than deer and not consumed as rapidly....
Based on ungulate biomass, the Blue Range Wolf Recovery Area (6,854 mi2 or 17,751 km2) can, in theory, support a an estimated 468 wolves. The target recovery area of 12,950 km2 (5,000 km2) could support between-212 and 599 wolves. We believe these estimates are high because they assume all prey are equal and will be consumed in proportion with availability. Given our experience with multiple prey systems elsewhere this is unlikely to occur. We therefore calculated wolf population estimates for individual prey species. Accordingly, elk in the Blue Range Wolf Recovery Area could support about 213 wolves, and the
combined deer species about 255 wolves.
Given the current ratio of wolves to ungulate prey, we conclude the reintroduced Mexican wolf population is not limited by food. Adequate prey are available to support and sustain a growing wolf population. Estimated wolf numbers derived from ungulate biomass were similar to numbers projected in the EIS. Because wolves depend primarily on ungulates for food, long-term survival of wolves in the study region depends primarily on protection of habitat for elk and deer....
10. HAS THE LIVESTOCK DEPREDATION CONTROL PROGRAM BEEN EFFECTIVE?
Although an effective livestock depredation program is critical for wolf recovery, effective assessment of such a program requires more specific guidance and data than we were provided....
Forty-two (42) reports of possible wolf-livestock interactions were recorded between March 1998 and March 2001. Of these, the Interagency Field Team concluded that 5 events were accidents, 9 were non-wolf predators [e.g., bear (Ursus americanus), lion (Felis concolor), coyote (C. latrans)], 18 were wolf related, and 10 were probably wolf related. That is, 28 events involved wolves or probably involved wolves. These included uninjured livestock, injured livestock, and killed livestock. The Interagency Field Team recorded 10 confirmed
livestock-wolf interactions where no injury or death occurred. At a minimum, 55% (26) of all free-ranging wolves have interacted with livestock. Thirty-six percent (17) have interacted with livestock 3 or more times. Approximately 10% have interacted with livestock 5 or more times. Approximately three-quarters of the livestock injuries or deaths occurred on National Forests. The number of reported livestock-wolf interactions varied seasonally. The interactions reported annually since the first reintroduction of Mexican wolves were; 5 from March 1998 to March 1999, 17 from March 1999 to March 2000, and 6 from Mar 2000 to Mar 2001.
Seventeen (17) reports of wolf interactions with cats or dogs were recorded between March 1998 and March 2001. These 17 reports included uninjured dogs, injured dogs, and killed dogs or cats. Of these, we concluded that; 13 interactions involved wolves; 1 interaction probably involved a wolf, and; 3 interactions cannot be classified using the data provided. The Interagency Field Team recorded 8 dog-wolf interactions where no injury or death occurred. Of the 13 interactions that definitely involved wolves, 5 resulted in the cat or dog being killed or injured....
Livestock are omnipresent in the Blue Wolf reintroduction area. Because of the extensive temporal and spatial distribution of livestock, interactions with wolves are unavoidable. From the information made available to us, we believe the Service has been responsive to wolf-livestock and wolf-domestic animal conflicts. An equivalent level of responsive will be necessary in the future. Similarly, livestock producers using public lands can make a substantive contribution to reducing conflicts with wolves through improved husbandry and better management of carcasses.
11. HAVE DOCUMENTED CASES OF THREATS TO HUMAN SAFETY OCCURRED?
Although no injuries or deaths have occurred, several wolf-human interactions have been reported. Consequently, evaluation of these incidences is largely qualitative based on our experiences with wolves in other parts of North America. We note that captive reared wolves released to the wild may behave differently than wild born wolves....
The Interagency Field Team reported eleven interactions between March 1998 and March 2001. On average, they reported one event every 3 months. However, the rate may be increasing (3 events from Mar 1998 to Mar 1999, 1 event from Mar 1999 to Mar 2000, 7 events from Mar 2000 to Mar 2001). If the rate is increasing, it is probably due to more wolves rather than an increased propensity for wolves to interact with humans. On average, one interaction was reported every 7 weeks from Mar 2000 to Mar 2001. Although data are too few to be certain, interactions do not seem to predominate in any particular time of the year. Seven (of 11) interactions involved something that would be expected to attract wolves (e.g., dogs, deer carcass, livestock). Specifically, 5 (of these 7) involved dogs. One (of 11) interaction was instigated by the people involved. In 2 (of 11) events, the people involved felt as though their lives were threatened....In 9 (of the 11) events, response involved an inspection of the site. In 2 events the people involved reported being fearful for their safety. However, experience suggests that because the people of event #7 responded appropriately, they were probably never in danger. In event #1, the wolf was shot. Event #8 is similar to cases in Ontario, British Columbia, and Alaska where wolves have injured people. In these all these cases, the people responded inappropriately to curious wolves or wolves attracted to food. Twelve (12) different wolves have been involved with human interactions. Approximately 25% of all the wolves that have been released into the wild have been involved in a reported wolf-human interaction....
The "immediate" fate of the 12 wolves was: 1 shot, 2 brought into captivity, 1 brought into an acclimation pen, and in 8 cases no attempt was made to capture the wolf. The "ultimate" fate of of the 12 wolves was: 2 shot, 3 permanently brought into captivity, 6 either are still free-ranging or died of natural causes, and for 1 wolf (i.e., #298, the potential data entry error) no data were available.
Wolf-human interactions have been reported consistently and regularly since the beginning of the program. Approximately 25% of the individuals in the free-ranging population have been involved with wolf-human interactions. As the wolf population grows, the Program should be prepared for steadily increasing frequencies of wolf-human interactions. Over time, the frequency of wolf-human interactions (per wolf) may decline with wild-born wolves that are less tolerant of humans. Because wolves can pass information between generations, the attraction to humans may take some time to extinguish. In the Republic of Georgia, for example, captive-born wolves were intensively trained to kill wild prey and to avoid humans before their reintroduction. This release procedure was considered successful after the third generation of wild-born wolves still showed the same behavior as their hand raised parents.
....It is critical that the Interagency Field Team keep comprehensive notes on wolf-human interactions. The Program should continue its practice of responding to all wolf-human interactions with immediate on site inspections and investigations. The Interagency Field Team appears to have made responsible decisions regarding the recapture of wolves involved in human interactions.
Table 6. Summary of wolf-human interactions reported for the Mexican wolf reintroduction program,
1. April 28, 1998--156
Wolf 156 was shot by a camper who feared for his
family's safety when the wolf came into their camp
and attacked their dog.
2. May 8, 1998--494
494 became a nuisance frequenting the town of
Alpine from 5/8/98 through 5/28/98 and was
permanently removed from the wild.
3. January 6, 1999--166, 482
Campbell Blue pair jerked down a deer carcass
hanging in some archery hunter's camp.
4. January 5, 2000--522
Female 522 hanging around hunters camp interacting
with dogs. Trapped and put in acclimation pen to
hold through hunting season.
5. April 14, 2000--166, 518
Dean Warren reported very aggressive encounter
with Campbell Blue pair with the female, 518
bumping his horse and passing under it. Wolves
also attacked one of his dogs. They followed him to
cabin and he held up in it until the wolves left.
6. May 16, 2000--298, 191
Renee Dupree jogging with 2 dogs when 2 wolves
approached -- wolves clearly interested in dogs.
Renee scares wolves away.
7. August 20, 2000--511, 509, 587, 590
Don and his cocker spaniel were out in the middle of
the meadow behind his trailer when 4 wolves ( most
likely Francisco) came tearing out of the woods
towards them. Don fired 1 hot in front of the wolves
but they kept coming ("one with a look of fierce
determination"). He fired a second shot as they got
closer and they reared away. He was very upset at
the situation and felt that they were a danger to both
people and animals/pets. Later that week, people
camped nearby observed several wolves and pups
resting in the shade under and around Don's trailer.
At the time, he was inside watching golf with his
dog, unaware that the wolves were outside. He was
irrate when he learned of the incident, stating that
this was not the behavior of wild animals and
concerned about what would have happened had he
or his dog come out of the trailer.
8. August 24, 2000--511, 509, 587, 590
Scott observed Francisco (and Cienega) on multiple
occasions during his time camping at Double
Cienega. Sometimes they came right through cmp <
5 ft of him taking pictures, although the pups seemed
more skittish, other times farther away within the
campground or out in the meadow. He also saw them
once farther up Double Cienega and "the shaggy
one" (yearling male 590) laid down w/in 10 ft and
just looked at him while he took pictures.
9. September 25, 2000--590
Yearling male 590 hanging around Double Cienega
Campground for the majority of the day.
10. September 29, 2000--511, 509, 587, 590
5-6 people camped in Double Cienega from about
8/21-8/30/00. Throughout the week they interacted
with Francisco. On multiple occasions they howled
the pack in, chased them on ATVs, left food out, and
shot blunt arrows at them. The wolves also chased
their horses, mules, and the people in the ATVs.
They were informed that this behavior was not
acceptable, and we explained that what they were
doing may possibly have negative effects on the
wolves behavior. On 8/30/00, while speaking with
the hunters, N. Sanchez observed the wolves chasing
the mules. He then hazed the wolves by running at
them and throwing rocks. They ignored him. We
first spoke with the group on about 8/23/00. We
informed them about the Mexican Wolf Recovery
Project, the presence of wolves in the area, and
proper behavior with respect to the wolves (ie. Do
not leave out food; keep an eye on mules/ horses; if
you see the wolves, yell and throw rocks at them.)
We also told them to let us know if they had any
interactions with the wolves.
11. October 1, 2000 Unknown
At about 0440 Cole went out the front door on the
porch and observed an animal in the driveway. At
first he thought it was a German Shepherd, then by the
color and size he realized it was a wolf. He shewed
it away and it headed west down the road. He tried
to follow it in his truck but lost track of it. When he
got back to the house it was by the back door eating
out of the dog dish. He shewed it away again and it
ran behind the house between the animal pens and
the barn. He checked the dog dish and it was empty.
He was not sure if there had been food in it or not.
Stark and Grant responded to the call made by Ms.
Leona Brown (the landowners sister). We looked at
the area where the report was taken and observed
large canid tracks in the driveway and yard. (track
size=5x3 1/2", in sand and gravel). No other tracks
were found in area. Stark and Armistead returned
on 10/2 at about 0500.
12. OVERALL CONCLUSIONS AND RECOMMENDATIONS
On 25 April we convened a meeting in Globe, Arizona to present our draft report to the Mexican Wolf Interagency Management Advisory Group (IMAG)....
Our conclusions and recommendations are based on our analysis of the data. We believe the long term objective is to protect the wolf population and meet human needs by reducing the potential for one to seriously encroach upon the other. Current circumstances demand that wolves be conserved in a human dominated landscape. This requires a systematic and rigorous approach to wolf recovery that integrates the social and economic aspirations of humans with the ecological necessities of wolves.
The ultimate factor determining population viability for wolves is human attitude. Thus, an active and fully enabled Recovery Program comprising private interests, non governmental conservation organizations, local, state, federal, and tribal agencies is essential to ensure success of any restoration. The biology, politics, and sociology of wolf reintroduction in the Blue River Wolf Recovery Area are too complex for recovery to be successful without a fully engaged and participatory Program. Fortunately, the Service has a successful history of reintroducing and effectively managing recovered wolf populations in other parts of the country. Based on this success and the first 3 years of the Mexican wolf reintroduction, we think that expecting a similar outcome in the Blue River Wolf Recovery Area is reasonable.
Overall we are satisfied with the progress of the reintroduction project since its inception in 1998. During May 2001, the Service reported that at least 28 wolves were free-ranging. Most of these animals are in social groups and the Service reports up to 5 litters have been produced in the wild this spring. Monitoring of reintroduced wolves has revealed that captive-born Mexican wolves can adjust to life in the wild by primarily preying on elk. This fact combined with the likely presence of several litters in the wild bodes well for the future. We believe the likelihood is high that continued application of the Service's current practices will result in the restoration of a self-sustaining population of Mexican wolves in the Blue Range Wolf Recovery Area. We believe, however, the Program should continue with some adjustments and modifications. Not surprisingly, our review revealed room for improvement....
Several factors currently hinder recovery of a self-sustaining and viable wolf population. Those that predominate are:
1. The small areal extent of the primary recovery zone, which greatly hinders the vigor of the reintroduction phase of the reestablishment project
2. The Service's insistence that wolves only inhabit the small Blue Range Recovery area, which is at odds with the naturally extensive movements that characterize gray wolves and current thinking regarding the viability of large carnivore populations.
3. The Service's embrace of a target population of 100 wolves (EIS, page 2) when such a population is not viable over the long term.
....If the Service adopts the recommendations presented below then the effectiveness of the reintroduction project and prospects for success will improve. Proper adoption of our recommendations will require a long-term and diligent effort by the Service. For many of the recommendations to be effective, biologists involved in the daily matters of the reintroduction effort must embrace them as standard operating procedures.
The current reintroduction project will greatly influence the future of the Mexican wolf recovery program since additional reintroduction projects will be required to remove Canis lupus baileyi from the list of endangered and threatened wildlife. Accordingly, we used our review to develop a few recommendations that consider Mexican wolf recovery overall. We also decided to consider programmatic issues that are germane to reintroduction, and issues the Service did not provide data for such as injuries resulting from capture. All of the recommendations below relate directly to the successful restoration of Mexican wolves [in] the BRWRC. We did not elaborate on several biological issues, identified in our recommendations as important, because the reintroduction process is in too early a stage to have accumulated sufficient data.
Biological and Technical Aspects
WE RECOMMEND THAT THE SERVICE:
Continue to develop appropriate opportunities to release (and re-release) wolves for at least
2 years to ensure the restoration of a self-sustaining population.
Begin developing population estimation techniques that are not based exclusively on telemetric monitoring. As the wolf population grows it will become increasingly difficult to maintain telemetric contact with all known or suspected packs. Consequently, the Service needs to develop non-telemetrically-based methodology (e.g., track station surveys, genetic sampling of hair or fecal material) for assessing the distribution and size of the wolf population.
Develop data collection forms and data collection and management procedures similar to those used by the red wolf restoration program in North Carolina.
Require biologist to promptly and carefully enter field data into a computer program for storage and analysis. The Service should require biologists to record data on a per wolf and per day basis. Data checking should be improved to eliminate data entry errors. In this regard, picklists and auto filling fields can simplify data entry and improve accuracy....
Make all data available for research and peer review.
Carefully consider using a modified #3 soft-catch trap for capturing Mexican wolves rather than the McBride #7. We are concerned that the #7 might cause unacceptably frequent and serious foot injuries. The Service might find that a modified #3 soft-catch trap is more appropriate for capturing wolves that have a high probability of being re-released or that are fairly small (e.g., smallish adults or pups). Modified soft-catch traps have been used to capture hundreds of red wolves that are similar in size to Mexican wolves and larger gray wolves (Quebec) with no serious foot injuries....
Encourage research that will help to inform future Program evaluations and adjustments.
The research we suggest is beyond the scope of the current Mexican wolf program because of resource limitations (personnel and fiscal) and the need to focus on the central mission of reintroducing wolves. However, research partnerships with universities and other organizations should be developed. Increasing the capacity of the Mexican wolf recovery program, should be a principle charge of the Recovery Team. The following areas are of contemporary conservation and academic interest and should be research priorities:
1. Population modeling (PVA and metapopulation model) and sensitivity analysis of shortand long-term demography and distribution
1. Assessment of new threats to population including new guild structure, disease, and human activity.
2. Habitat viability analyses of the release area and projected population range (environment, resources, carrying capacity, spatial characteristics, etc.)
3. Development of guidelines for decision-making in conflict situations
4. Reassessment of policies for intervention in the release phase
5. Assessment of monitoring programs
6. Evaluation and design of long-term management program, including
Page 63 of 85 Mexican wolf review . . . Paquet et al. 2001
a. Evaluation design of long-term monitoring program
1. demography and population range
2. genetic surveillance
3. health surveillance
4. long-term adaptation of individuals and population to ecosystem
5. effects on ecosystem (predation, displacement)
7. The interaction of Mexican wolves with other carnivores in the reintroduction area.
Reintroduction or recolonization of wolves influences the behavior, abundance, and distribution of other carnivore species. For example, wolf recovery in the Rocky Mountains has resulted in interference and exploitation competition among wolves, bears, coyotes, and cougars, causing changes in the composition and structure of the carnivore guild.
Develop a contemporary definition of a biologically successful wolf reintroduction and the criteria needed to measure success. The latter includes methods and time scales. Specific issues that need to be considered are:
1. How many wolves and how many breeding pairs will result in a demographically and genetically viable population?
2. How do metapopulation dynamics affect the viability of Mexican wolves?
3. How broad a geographic area would such a population inhabit?
4. What affect will a viable population have on elk, deer, cattle, etc.?
5. What target population size will lead to long-term demographic viability?
6. What target population size will lead to long-term genetic viability?
We propose the application of the IUCN Red List Categories (IUCN 1994) to assess success and failure at 5 and 10 years following completion of the release phase. The classification is based on an assessment using 5 criteria; population reduction, area of occurrence and occupancy, 2 criteria for population density, and a quantitative analysis of the extinction probability. If the population is assessed as "critically endangered" after 10 years the project should be considered a failure because there is a very high risk of extinction in the wild in the future. The minimum standard for success should be vulnerable or better. Vulnerable populations still face a high risk of extinction in the medium-term future and require ongoing management....
Valuational and Organizational Aspects
WE RECOMMEND THAT THE SERVICE:
Modify the recovery team by inviting an appropriate individual other than the recovery coordinator to serve as the team leader. While ultimate responsibility for Mexican wolf recovery would still reside with the recovery coordinator, enlisting another individual to serve as team leader would increase the capacity of the recovery program. Other recover program use this administrative structure and it works well (e.g., the California condor recovery program).
Instruct the modified recovery team to revise by June 2002 the 1982 recovery plan. A revision of the recovery plan is long overdue for several reasons. First, the current plan does not contain any standards for removing C. l. baileyi from the endangered species list. Second, since the plan was approved great advances have been made in the science of conservation biology; such advances would greatly instruct revision of the recovery plan. Finally, due to work with red wolves in the southeast, gray wolves in the Great Lakes states and the northern Rockies, and Mexican wolves in the Blue River Wolf Recovery Area we have a much greater understanding of wolf reintroductions and management; such understanding would greatly inform revision of the Mexican wolf recovery plan.
Immediately engage the services of the modified recovery team. The challenges of wolf restoration are many and varied. Meeting such challenges requires a restoration effort that is itself diverse and capable. The current reintroduction project and Mexican wolf recovery in general would benefit substantially from the efforts of a fully engaged recovery team.
Immediately modify the final rule (Parsons 1998) and develop the authority to conduct initial releases into the Gila National Forest. Several releases conducted during the first 3 years of the reintroduction project resulted in wolves settling much of the primary recovery zone in the Blue River Wolf Recovery Area. As work elsewhere has revealed, wolves should not be released in areas that support resident animals. Over time, it will become harder for the Service to find suitable release sites in the primary recovery zone. The Service can best address this problem by obtaining the authority to conduct initial release in the secondary recovery zone, most notably the Gila National Forest. This recommendation was first made to the Service by a panel of experts...enlisted by the Service to review the reintroduction program in January 1999. Despite the Service's approval of the recommendation, they have taken no implementation action. This is by far the most important and simplest change the Service can make to the existing reintroduction project. The Gila National Forest is approximately 75% of the 4.4 million acre Blue River Wolf Recovery Area. The Gila Forest includes about 700,000 acres that are roadless and free of livestock. Several high-quality release sites are available in the area. Using them is the best way for improving the cost-effectiveness and certainty of the reintroduction project. Accordingly, we strongly recommend that the Service immediately take whatever action is necessary to conduct initial releases of captive-born (and wild-born if appropriate) Mexican wolves to the Gila National Forest.
Immediately modify the final rule to allow wolves that are not management problems to establish territories outside the Blue River Wolf Recovery Area. For specific language and instruction for this modification we strongly recommend that the Mexican wolf recovery program review the final rule promulgated for the gray wolf recovery in the northern Rockies (Bangs 1994). During the first 3 years of the reintroduction the Service recaptured some Mexican wolves simply because they left the Blue River Wolf Recovery Area. As the wolf population grows, more animals will disperse from the Blue River Wolf Recovery Area. Retrieving animals because they wander outside the primary recovery area is is inappropriate because it is:
1. inconsistent with the Service's approach to recover wolves in the southeast, Great Lakes states, and the northern Rockies;
2. will lead to serious logistical and credibility problems as the wolf population grows and more wolves disperse from the area; and
3. needlessly excludes habitat that could substantially contribute to recovery of Canis lupus baileyi.
Before the current Mexican wolf reintroduction project was initiated, the red wolf recovery program adopted a similar approach with dire consequences. Extensive tracts of public land and some private land outside the Blue River Wolf Recovery Area are suitable for wolves. Consequently, we strongly recommend that the Service develop the appropriate flexibility to allow wolves to occupy lands outside the Blue River Wolf Recovery Area. We believe that obtaining the requisite flexibility will require that the Service modify the final rule currently governing the reintroduction project.
We recognize that the statements above as they relate to private land may cause controversy so we offer the following remarks. Allowing Mexican wolves to inhabit suitable tracts of private land (e.g., large holdings) in the absence of problems, would bring the reintroduction project into compliance with Service-led efforts to recover wolves elsewhere. Allowing wolves to inhabit private property in the absence of a problem should not be construed to mean that the Service would begin to actively target private lands as wolf habitat that needs to
be settled. Quite the contrary, and note that nowhere is the Service effecting management of private land to promote wolf conservation. However, throughout the U.S (except in the Blue River Wolf Recovery Area) if a wolf wanders onto private property and does not cause a definable problem, and its mere presence is not a definable problem, then the Service is not required to remove the animal even if the landowner demands such action.
Such an approach to wolf recovery is consistent with the determination in the United States that the public owns wildlife, rather than private landowners. Within limits, landowners can manage their property in a way that promotes or hinders the welfare of wildlife. However, through laws enforced by state and federal officials, citizens decide under what circumstances wildlife can be captured and moved or killed from public and private land. Such decisions are not the prerogatives of the landowner, regardless of whether the animal(s) in question are naturally occurring or present because of a reintroduction program.
In sharp contrast with the Service's approach elsewhere, the Mexican wolf project developed a rule that requires wolves to be removed from public and private land outside the Blue River Wolf Recovery Area, even in the absence of a problem. Such regulations are inappropriate for at least 2 reasons: 1) they are nearly impossible to effectively carry out as the wolf population grows because of the difficulties of managing an ever-increasing number of wide-ranging dispersing animals, and 2) they establish a precedent that could be effectively used to argue for the removal of other endangered species inhabiting certain tracts of public or private land.
Certainly local opposition to the Mexican wolf reintroduction program affected the development of such a rule. Indeed, the recovery program coordinator assumed from personal knowledge of local politics and sentiments that a more restrictive rule would have significantly hindered and possibly caused the termination of the project. Maybe this was a valid assumption. Opinion polls, however, suggest widespread and persistent local support for wolf recovery in the southwest. Regardless, noting that wolf recovery elsewhere has faced substantial opposition is instructive, but the Service did not promulgate similarly onerous rules. And to date, recovery efforts elsewhere have been quite successful.
Resist any opportunity to reintroduce Mexican wolves in the White Sands Wolf Recovery Area (WSWRA). Two independent assessments suggest that the WSWRA could support only 20 to 30 wolves; such a population is not viable. The inability of the WSWRA to support a viable population of wolves is due to the area's relative smallness (about 10,311 km2 or 4,028 mi2) and its distance from other suitable habitat. For example, the WSWRA is about 100 km (62 miles) from the extreme eastern edge of the BRWRA. While wolves can easily traverse such a distance, the "dispersal area" comprises very poor wolf habitat, supports the town of Truth or Consequences, New Mexico in its core, and is bisected by the heavily traveled federal Interstate 25. Accordingly, the USFWS should not expend resources on reintroducing wolves to the WSRWA.
Provide biologists with opportunities to visit other wolf projects to gain training with capturing and handling free-ranging and captive wolves.
Station the field coordinator in the Blue River Wolf Recovery Area (e.g., in Glenwood or Silver City, New Mexico or Alpine, Arizona) and insist that this person be intimately involved with all aspects of fieldwork (wolf management; public relations; data collection, management, analysis, report preparation; etc.). We think it would be a serious mistake to station the field coordinator in the Regional Office in Albuquerque. Such a decision would add a level of complexity that is entirely unwarranted.
Put forth a concerted effort to develop realistic expectations for the project. Restoration is an imprecise process that is by definition "heavy-handed". The Service needs to constantly remind the public and the media of this fact. It is certain that the Service will have to overcome great challenges in the future. Such challenges will mean that intervention will be required, that wolves will disappear, and that some animals will die. But just as certainly, meeting the challenges will ensure the restoration of a self-sustaining population of Mexican wolves in the Blue River Wolf Recovery Area.
Initiate programs to educate people about wolf behavior. In most events involving humans, wolves are interested in dogs or food (e.g., carcasses, dog food, etc.). Members of the program expected to respond to wolf-human interactions should be well educated on the nature and variety of reports from Algonquin provincial park, Alaska, and British Columbia. The Program should contact other western communities and agencies that have dealt with large carnivore-human interactions (e.g., mountain lions, bears, wolves). The Program should also actively warn people that dogs, deer/elk carcasses, and livestock carcasses may attract wolves. Although the danger is not the same, hunters should be advised to behave as though they are in grizzly bear country.
Require livestock operators on public land to take some responsibility for carcass management/disposal to reduce the likelihood that wolves become habituated to feeding on livestock. Currently livestock grazing is permitted on about 66% of the Blue River Wolf Recovery Area. At least 3 packs were removed from the wild because they scavenged on dead livestock left on national forest lands. Such scavenging may predispose wolves to eventually prey on livestock. Accordingly, reducing the wolves' access to carcasses will greatly facilitate coexistence between ranchers and wolves in this portion of the recovery area carcasses. While some predation on livestock is inevitable, reasonable means of reducing the frequency of occurrence will enhance wolf recovery so that is respectful of the needs and concerns of livestock producers. Consequently, livestock producers using public land in occupied Mexican wolf range should be required to exercise reasonable diligence in finding livestock that have died to either dispose of the carcass or enable the Service to do so. Such diligence will probably reduce predation on livestock, which in turn will improve the cost-effectiveness and certainty of the reintroduction project.
When writing or lecturing about the project, the Service should emphasize a community approach to understanding the wolf reintroduction project and its effect on other species and ecological processes. Conservation policy is shifting away from the preservation of single species toward preservation and management of interactive networks and large-scale ecosystems on which species depend. It is extremely important that the Service view the wolf reintroduction program in this context.
Figure 1. Summary of Mexican wolf radio telemetry data, 1998-2001
Figure 2. Monthly radio-telemetry locations of reintroduced Mexican wolves, Arizona, 1998-2001
Figure 3. Many telemetry locations resulted from data entry errors. For example, numerous locations were in the state of California and in the Gulf of California
Figure 4. Variation among wolf packs in the proportion of telemetry locations within the primary zone and within the recovery area (Apache/Gila N.F.). These data include all telemetry locations of reintroduced Mexican wolves from 3 March 1998 to 3 March 2001.
Figure 5. Temporal trends in the proportion of telemetry locations (pooled across all packs) within the primary zone (Apache N.F.) and within the recovery area (Apache/Gila N.F.). These data include all telemetry locations of reintroduced Mexican wolves from 3 March 1998 to 3 March 2001
Figure 6. Approximate area occupied by free- ranging Mexican wolf population in Arizona and New Mexico, 1998-2001
Figure 7. Density of free-ranging Mexican wolf population in Arizona and New Mexico, 1998-2001
Figure 8. Seasonal distribution of free-ranging Mexican wolf population in Arizona and New Mexico, 1998-2001
Figure 9. Polygons reflecting the spatial extent of pack home ranges in relation to the primary zone (Apache N.F.) And recovery area (Apache/Gila N.F.). These data include all telemetry locations of reintroduced Mexican wolves from 03 March 1998 to 03 March 2001
Figure 10. Projected numbers of breeding pairs (in the EIS) and actual numbers of litters for reintroduced Mexican wolves, 1998-2001
Figure 11. Actual and projected numbers of recruits for reintroduced Mexican wolves, 1998-2001
Figure 12. Causes of wolf mortality for Mexican wolves reintroduced to Arizona, 1998-2001.
Figure 13. Cause specific wolf mortality for Mexican wolves reintroduced to Arizona, 1998-2001
Figure 14. Survival analysis of reintroduced Mexican wolf population assuming that recapture represents a mortality event. Analysis was conducted for the period 1998-2001.
Figure 15. Survival analysis of reintroduced Mexican wolf population assuming that recaptures do not represent a mortality event. Analysis was conducted for the period 1998-2001.
Figure 16. Projected and actual annual growth rates of free-ranging Mexican wolf population. Actual growth rate is strongly influenced by frequent intervention
Figure 17. Projected and actual sizes of free-ranging Mexican wolf population, 1998-2001.
Figure 18. Number of free-ranging radiocollared Mexican wolves, 1998-2001. The difference the max and min accounts for 4 wolves whose signals were lost, and in one case, a wolf that threw its collar
Figure 19. Growth rates of other recovering wolf populations.
Figure 20. Mean annual growth rate for other recovering populations
Figure 21. Number of wolves over time in other recovering populations
Figure 22. Mean monthly growth rate (r) since March 1998. The expected value of r is 0.02. The standard error is 0.07.
Figure 23. Mean monthly growth rate (r) since December 1998 (when population went
temporarily extinct). The expected value of r is 0.06. The standard error is 0.08.
Figure 24. Because of frequent interventions the vital rates we derived (survival and population growth) are unlikley to reflect the population?s future viability. A balance between intervention and the effects of natural population processes is needed
Figure 25. Prey (n = 55) probably killed by reintroduced Mexican wolves, 1998-2001
Figure 26. Potential number of wolves that, in theory, could occupy target objective of 12,950 km? (5,000 mi?) within the Blue River Wolf Recovery Area. Estimates are based on prey biomass available to wolves and are maximum numbers. The individual contribution of ungulate prey species is shown for comparison with other studies
Figure 27. The number of livestock-wolf interactions fluctuated seasonally in the primary recovery zone
Table 1. Known births and recruitments of reintroduced Mexican wolves recorded from 1998-2001. Only 1 litter was conceived in the wild
Table 2. Population events recorded for reintroduced Mexican wolf population between 1998 and 2001
Table 3. Potential wolf numbers (ranges) for recovery areas based on predicted population densities
Table 4. Numbers of domestic animal injuries and deaths due to wolf depredation. The data are for confirmed, probable and unconfirmed wolf depredations
Table 5. Ownership of property where domestic animal injuries and death due to wolves took place. The data are for confirmed, probable, and unconfirmed wolf depredations.
Table 6. Summary of wolf-human interactions reported for the Mexican wolf reintroduction program, 1998-2001
Table 7. Biological criteria for measuring project success of Mexican wolf reintroduction at about 5 and 10 years following completion of reintroduction phase.