 WolvesWolf History, Conservation, Ecology and Behavior
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Wolfology Item #1315
Source
v.10 (2001)
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Group Size and Home Range of the Arabian Wolf (Canis lupus) in Southern Israel
Reuven Hefner & Eli Geffen
2001
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Abstract
The Arabian wolf (Canis lupus arabs) is a desert-adapted canid that occurs throughout arid regions in the Middle East. We examined group size, home range, habitat selection, and dispersal of Arabian wolves in the southern Negev Desert.
 The gray wolf (Canis lupus) is one of the most persecuted mammal species. In this century, gray wolves have been eradicated from much of North America and large areas of western Europe. In other parts of Europe (e.g., Italy, Spain, and Norway), small or remnant populations have persisted. In general, wolves are abundant only in regions where human density is low.
In the Middle East, a small, desert-adapted subspecies, the Arabian wolf (C. l. arabs) occurs. These wolves occupy arid flats and mountains throughout deserts of the Arabian Peninsula, Syria, Jordan and Israel. The Arabian wolf is rare throughout most of the Middle East, with the exception of Israel. In the Arabian Peninsula and Jordan, vast areas are used by the nomadic Bedouin for grazing of livestock, and they consider the wolf to be the major predator of their goats and sheep. Systematic shooting and trapping of Arabian wolves has nearly eliminated this carnivore from most areas in the Middle East. Harassing or killing wolves is prohibited in Israel. As a result, the population of wolves in the Negev Desert is relatively dense; 91-159 individuals in ca. 9,600 km2.
Arabian wolves in the Negev Desert feed mostly on trash, carrion and agricultural products. They occasionally hunt hares (Lepus capensis), gazelles (Gazella dorcas), ibexes (Capra ibex), and livestock.
The aim of our study was to investigate ranging patterns and dispersal of Arabian wolves in the Negev Desert. Specifically, we studied size of foraging groups, home range, survival, dispersal, and use of human-dominated habitats. We anticipated that wolves in the southern Negev Desert would occupy relatively small ranges and forage in small groups mostly around human settlements.
MATERIALS AND METHODS
Study site.--The study was conducted in ca. 600 km2 of the southern Negev Desert. The climate in the region was extremely arid....The study area has two distinct sections: the Eilat Mountains Nature Reserve and the bottom of the Rift depression. The Eilat Mountains Nature Reserve was located along the western side of the Rift Valley, a rugged region of mountains and canyons. The Rift depression north of Eilat (elevation 100 m) was an undulating area of dunes, alluvial fans and flat salt marshes. Most of this area, excluding the relatively sterile salt marshes, was an arid savannah-like habitat. There were eight human settlements in the study site, all situated along the bottom of the Rift Valley. Those communities were agricultural and specialized in dairy products and crops.
Field methods.-- ....Traps were staked to the ground around carcasses of domestic ungulates or gazelles and were observed from a distance at 2-h intervals for several nights. Wolves in our study site were habituated to human presence; hence, our frequent visits did not disturb the animals and enabled us to prevent injury to the trapped wolves. Traps were covered during daylight periods.
.... Adults were fitted with a 250g radiocollar....Each radio-collared wolf was monitored for 1-2 nights/month. They were tracked sequentially from a vehicle throughout the night, with locations recorded about every 30 min. Wolves became habituated to our vehicle and were observed with a spotlight from a distance of 50-100 m. We defined a foraging group as a collection of individuals found together during a particular observation; these may not necessarily constitute an entire pack. We recorded size and composition (sex and age) of foraging groups for each observation. In some instances, we could not distinguish sexes, but juveniles months were clearly distinguishable. Because most wolves in our population were unmarked and occasionally we were unable to reliably distinguish between individuals in the dark, the existence of large and stable packs could not be established....
Data analysis.--Mean daily activity time was compiled only from night observations when individual wolves were sequentially tracked....
....We defined two habitat types: human-dominated (e.g., plantations, settlements, and garbage pits) and natural (undisturbed areas)....
RESULTS
Capture, dispersal and survival.--From July 1991 to November 1995, 38 wolves were trapped, weighed, and measured. The sample included 5 adult males, 11 adult females, 10 juvenile males, and 12 juvenile females. Twenty-three wolves were fitted with radiocollars. Subsequent monitoring revealed the turnover rate of the collared population to be high. Wolves usually dispersed or died in 2-4 years. The status of seven wolves could not be determined within 1 year, four after 2 years, and one after 3 years. Most of those were likely the result of transmitter failures. However, we recorded five deaths and seven instances of longdistance dispersal out of our study site. Three of the dead individuals were shot after crossing to Jordan. The seven individuals that dispersed moved 50-150 km N of our study site and settled there. Four dispersed after 2 years and three after 3 years. Three of the dispersing individuals were males, and four were females. Those individuals were never observed again at the study site but were known to be alive elsewhere. Annual survival rate was 0.81 +/- 0.15. This estimate was based on 12 individuals known to be alive and five recorded dead at the end of the study.
Activity.--Wolves were active mostly at night. During the day, they stayed under cover, including bushes, boulders, and shallow caves. Activity started in the late afternoon and ceased in early morning. Only 4.3% of 671 locations recorded for 14 individuals during the night were inactive. Further, only three active locations were collected after 0900 h, and only one active location was obtained before 1700 h. Seasonal changes in nightly activity pattern were not detected ...Seasonal differences in distance travelled were not detected. Males and females travelled similar distances.
Group size.--Wolves travelled in small groups. Mean foraging group size was 3.2 +/- 2.4.... Additionally, 74.6% and 83% of foraging groups (where we were able to identify individual sex) had a single adult male and a single adult female, respectively. About 23% of our observations were of a lone wolf, and 69% were groups of 1-3 wolves. The only two known packs, where all individuals were radiocollared, consisted of three individuals each (two males and a female in one; two females and a male in the other). Overall, no seasonal change in foraging group size was detected. Number of adult females per group was similar at all seasons; however, number of adult males per group was larger during winter....
Home range and habitat use.-- ....Analysis of range utilization indicated that active wolves spent on average 52.3% of their foraging time in the vicinity of human settlements. Two settlements (Gerofit and Qetura) were small farming communities surrounded by fields and had livestock housed in small enclosures. Another site that was frequently visited was Sheluhat Shaharut, a 400-700-m high cliff extending along the west side of the Rift depression. Wolves spent most of the daytime hours (while inactive) at the base of the cliff. The other four wolves we tracked also exhibited peak activity near human settlements and fields within the study area. On average, 24.0% of the area in a home-range was human-dominated habitat. Comparisons between observed and expected distribution of locations indicated that five wolves selected human-influenced habitats. Two other wolves that occupied the smallest ranges did not select human settlements.
DISCUSSION
In most areas where wolves exist, humans were the major mortality factor. Of the five mortalities of wolves recorded in our study, three were shot, one died of old age, and the cause of death for the last was unknown. Mech (1970) suggested an overall survival rate of 80% for adult wolves in Minnesota. Annual survival estimates of 72% and 64% were calculated from a large number of radiocollared adult wolves in Minnesota. The annual survival rate observed for Arabian wolves in our study area was similar to those estimates.
A wolf pack is generally composed of related individuals, excluding the mating pair. Studies on wolf populations in North America indicated that group size may vary between 2-20 and may be related to food availability or the size of prey. Arabian wolves in the southern Negev Desert travelled in small packs (3-4 individuals), and the largest group we observed was 17. Aggregation into large groups occurred only when food was abundant (i.e., around a carcass or at a garbage pit). Shalmon (1986) reported that 78.7% of foraging groups he observed at our study site numbered three or less individuals. Group size, on average, did not fluctuate throughout the year. The only change that we detected was an increase in the number of males during winter -- a change that may be associated with the mating season.
Most groups had a single pair of adults. Shalmon (1986) observed a single wolf in 27% of observations, pairs (i.e., adult male and adult female) in 19.3%, and an adult female with a juvenile in 14.2% of cases. Groups of two adult males and an adult female or a single adult male with two adult females were recorded in 11.6% of observations. Considering that most of the wolves in our population were unmarked and that we were unable to reliably distinguish between individuals in the dark, the existence of large and stable packs could not be established beyond doubt. However, in most cases, foraging groups were small and inconsistent in composition, indicating that the need to form large and stable packs is reduced compared with wolf populations observed in North America. We seldom observed foraging groups being rejoined by other group members during daytime. In Italy, where wolves have lived with humans for centuries, foraging groups are small, one or two individuals. These individuals rejoin the rest of the pack (which usually consists of two to four animals) upon return from night wanderings. Boitani (1992) believed that strategy allowed wolves to move safely in areas populated by humans. Foraging in small groups can be explained by the fact that the wolves in the Rift Valley are largely omnivorous and feed mostly on surplus human production, contrary to most known wolf populations that actively hunt....
Arabian wolves in the southern Negev Desert occupied considerably smaller home ranges than reported elsewhere. A single adult female that was monitored for 7 months in the central Negev Desert during 1982 occupied 60.3 km2. In North America wolves that prey on deer (Odocoileus sp.) have territories as small as 125 km2, but populations that prey on larger ungulates tend to occupy larger ranges (1,250-1,400 km2). The small home ranges of the Arabian wolf probably reflect the clumped distribution of the main food source, which is often located near the settlements along the Rift Valley. Furthermore, we suspected that territory boundaries at our study site are infrequently defended against neighboring wolves, especially around rubbish pits and fields where food is abundant and its renewal rate is high and stable.
Our results imply that the Arabian wolves in the southern Negev Desert have become habituated to the intensive usage of their habitat by humans. Arabian wolves are largely omnivorous and opportunistic feeders. A detailed analysis of 777 wolf scats in the southern Negev Desert revealed that 51.4% contained vegetative material, 37.2% human garbage, and 62.5% hair from cow carcasses. Only 6.3% of scats contained native mammals (gazelles, hares), excluding small rodents. Carrion was obtained at pits where dead livestock were frequently dumped. The above findings suggest that most food of wolves was scavenged. Such dietary composition has apparently enabled the Arabian wolf to live around humans but avoid conflict by shifting away from systematic predation on livestock. Reports of wolves in North America feeding on garbage are sparse, but Italian wolves obtain 60-70% of their food from the open garbage dumps of nearby villages.
Mendelssohn (1982) classified the wolf population of the Negev Desert into two separate populations. Our data on dispersal distances of wolves suggested that this division is probably not justified. We recorded four individuals (17.4% of the collared individuals) that dispersed 100-150 km N of our study site. Population genetics theory predicts that only a few migrants are sufficient to prevent significant divergence among subpopulations resulting from random genetic drift. The number of individuals exchanged per average wolf lifetime (ca. 5 years) between the two wolf populations in the Negev Desert is probably greater than a few individuals. Therefore, it is unlikely that these wolf populations can remain genetically separated with such a high exchange rate. Furthermore, the range of body weights of adult male and female wolves at our study site were not different from the values outlined by Mendelssohn for the desert C. . pallipes....This evidence suggests that wolves in the Negev Desert should be considered as a single continuous population.
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