We studied the influence of human activity, hunting of prey by wolves, reproduction, and weather conditions on daily patterns and duration of activity of 11 radiotracked wolves (Canis lupus) in the Bialowieza Forest (Poland) from 1994 to 1999. On average, wolves were active 45.2% of the time and traveled 0.92 + or - 0.05 km/h....Wolves were active throughout the day, but their activity peaked at dawn and dusk, which coincided with periods when they killed most prey. Periods of reproduction and high temperatures had less pronounced effects on activity patterns. Human activity and other factors did not significantly affect the wolves' daily activity patterns. The influence of humans may be indirect if hunting of ungulates by humans modifies activity patterns of the wolves' prey. We conclude that the daily activity patterns of wolves in our study area were mainly shaped by their pattern of hunting prey.
Radiotracking studies of wolves (Canis lupus) have suggested several factors that are likely to influence their activity patterns. These factors are human activity (Ciucci et al. 1997; Vila et al. 1995), hunting of prey (Ballard et al. 1991; Harrington and Mech 1982; Mech and Merrill 1998; Murie 1944), reproduction (Ballard et al. 1991; Harrington and Mech 1982; Vila et al. 1995), and weather (Fancy and Ballard 1995; Kolenosky and Johnston 1967). However, importance of each of these factors may vary according to geographic area. This causes dissimilarities in activity patterns of wolves from different study sites: wolves were nocturnal in Italy (Ciucci et al. 1997); nocturnal with a tendency to bimodal activity in Spain (Vila et al. 1995); active throughout day and night in Ontario, Canada (Kolenosky and Johnston 1967); and most active from 2200 to 0600 h in summer and from 0700 to 1600 h in winter in Alaska (Fancy and Ballard 1995). Wolves also show significant variation in daily activity patterns among individuals of a pack as observed at denning and rendezvous sites (Ballard et al. 1991; Harrington and Mech 1982).
We hypothesized that human and prey activities would have the most important influence on activity patterns of wolves. The activity patterns of wolves and their prey are theoretically dependent on one another because prey strive to avoid wolves, whereas wolves adapt their temporal hunting pattern to the times when prey are most vulnerable. Knowledge about temporal distribution of wolf kills could improve understanding of interactions between wolves and their prey, but information available is limited to data based on times when wolves leave den sites for hunting and times when they return afterward. The influence of humans on activity of wolves is especially important to determine....We expected that wolves living in areas with high human activity would either change their activity patterns to avoid encounters with humans or become used to the presence of people. In Central Europe, where hunting by humans strongly influences activity patterns of ungulates, hunting patterns of recolonizing wolves could cause a shift in activity patterns of their prey.
To obtain information about daily patterns of wolf activity, kills by wolves, and human activity, we radiotracked wolves, determined the time when wolves killed prey, and recorded human activity in the Bialowieza Forest, Poland. This area lies on the western edge of the large wolf range that encompasses the boreal and temperate forest zone of Eurasia. The aim of our study was to determine how human activity, hunting for prey, reproduction, and weather conditions affect activity of wolves.
MATERIALS AND METHODS
Study area....The forest consists of deciduous, coniferous, and mixed tree stands. Mean daily temperature is - 5[degrees]C in January and 18[degrees]C in July, annual precipitation is 641 mm, and length of snow cover averages 92 days but ranges between 0 and 132 days. The maximum depth of snow during this study was 63 cm. Our study area was the Polish part of the Forest, which includes the....National Park and a commercial forest. Timber harvest, reforestation, and hunting take place in the commercial forest....
Human density is about 7 inhabitants/km in the...Forest and 70 inhabitants/km in the region surrounding the study area (Bialystok administration district)....Forestry is the main source of human activity in the commercial forest. Tourists contribute largely to human activity in summer, particularly in the National Park. Mushroom collectors and hunters are active seasonally. Traffic in the forest consists mostly of cars, trucks, or tractors. Tourists mainly move on foot or bicycle and usually remain on roads and trails.
Three wolf packs roamed the Polish part of the...Forest at the beginning of this study. The core area of 1 pack (National Park pack) was the strict reserve of the...National Park, where there is no motorized traffic and human access is restricted. Another pack inhabited the northwestern part of the...Forest (Ladzka pack). The 3rd pack lived in the southern part of the study area. This pack split in December 1997 into 2 packs (Lesna packs), but their home ranges overlapped nearly completely after the separation. Wolves have been protected since 1989 in the Polish part of the...Forest, but humans are still the main mortality factor. During our study, 6 of 12 radiocollared wolves were shot or died in snares set by poachers for wild boar. In the Belarussian part, hunters killed between 1975 and 1994 on average 80% of the wolf population per year. Wolves usually flee when they meet humans in the forest.
The main prey of wolves in the...Forest are red deer (Cervus elaphus), followed by wild boar and roe deer (Capreolus capreolus). During this study, mean densities of prey for the whole study area were about 3-7 red deer/km, 1-6 wild boar/km, and 1-5 roe deer/km.
Radiotracking of wolves. We captured 12 wolves from 4 packs, either with Aldrich foot snares equipped with radioalarm systems (3 wolves)...or by the fladry-and-net method (9 wolves)....Fladry are lengths of rope to which colored strips of cloth of about 40 by 15 cm are attached at intervals of about 50 cm. Wolves usually avoid crossing lines of fladry and can therefore be driven by a line of beaters toward nets set on 1 side of an area surrounded by fladry. We immobilized wolves with 1.2-1.8 ml of a xylazine-ketamine mixture and fitted them with radiocollars. The radiocollars of 5 wolves were equipped with activity sensors. We estimated the approximate age of wolves to range between 5 months and 9 years during the period of radiotracking, based on the date of capture, body mass, and tooth wear.
During 24-h radiotracking sessions of usually 6 days (range 1-9 days), we noted activity and location of a radiocollared wolf continuously every 30 min (March 1994 to December 1996) or every 15 min (December 1996 to September 1999). We obtained locations of a wolf by triangulation from forest roads. We determined position of the wolf from at least 2 bearings taken from different places at intervals of no more than 5 min. The number of locations of 11 radiotracked wolves (9 females, 2 males) ranged from 557 to 8,336 locations/wolf during 3-42 months of radiotracking (total of 40,305 radiolocations)....
For 15% of the time during which we followed the 4 wolf packs, we radiotracked 2 wolves in a pack simultaneously instead of 1 wolf. Activity and movement of the radiotracked wolves of a pack could therefore have been partly autocorrelated. However, wolf packs are not fixed units, and wolves show significant variation in daily activity patterns among individuals in a pack at denning and rendezvous sites. In our study, we noted both activity and location of radiotracked wolves separately because wolves often did not show the same behavior at the same time, and packs regularly separated....We therefore decided to use the individual wolf rather than the wolf pack as the sample unit....
Prey of wolves and activity of humans. From 1997 to 1999, we made an effort to find the remains of all prey killed during continuous radiotracking sessions. We tracked wolf trails in snow to find prey remains or, if there was insufficient snow cover, organized a search party that included a dog whenever possible. If we found the place where wolves had killed their prey, we defined the time at which wolves killed the prey as the moment when they were 1st radiolocated at this point. Although we think that we found most prey when conditions were favorable (snow cover), we probably missed some prey remains in summer, especially during periods when wolves also take small prey such as calves of deer or young wild boar. We therefore did not compare differences in the time wolves killed prey among seasons.
To document the daily pattern of human activity in the study area, we observed vehicular and foot traffic either visually or with a magnetic count card at 39 counting points on roads in the forest from 1997 to 1999. During visual counts, which lasted for units of 2-24 h (total of 569 h), volunteers counted people and vehicles that passed a given counting point. In addition, a magnetic traffic counter card placed in forest roads recorded number of passing vehicles for continuous periods of 1 week (total of 5,712 h)....
If human activity modified the activity pattern of wolves, wolves in regions with higher human activity should reduce their activity and movement during the time of human presence compared with wolves in regions with lower human activity. We therefore compared mean activity and movement of wolf packs during the time of highest human activity to assess effect of humans on activity patterns of wolves. We did not compare human and wolf activity patterns directly because a mere correlation would not prove an effect of humans on wolf activity....
General activity patterns of wolves and humans. Wolves were active 45% of the day on average, but bouts of activity and inactivity were relatively short. Most active and inactive bouts lasted only 15 min (46% and 37% of bouts, respectively) or 30 min (18% and 16%, respectively), whereas only 19% of active and 30% of inactive bouts were longer than 1 h. The longest activity bout lasted 7 h and the longest bout of inactivity 9.5 h. Activity of wolves was highest at dawn and dusk, which also coincided with the longest activity bouts. Activity bouts decreased in length with increasing age of wolves but length of inactive bouts, time active, or distance traveled did not. In all months, wolves in the...Forest were active throughout the day but with peaks at dawn and dusk and troughs in the middle of the day and middle of the night....
Human activity was lowest both in intensity and length in the home range of the National Park pack, especially in winter. However, during the main period of human activity (0700-1700 h), distances traveled by wolves of the National Park pack were not greater than those traveled by wolves living in the commercial forest in winter or summer . During the same part of the day, wolves from the National Park pack were not more active than wolves from the commercial forest in winter but were even less active in summer.
Prey. Wolves killed most of the prey that we found and for which we could estimate time of killing in the 6 h around sunrise and in the first 4 h after sunset. They killed less often in the night and rarely in the middle of the day. Compared with length of each period of day during days of hunts, wolves killed 1.8 times more than expected at dawn, dusk, and during moonlit nights but not significantly more than expected during night. Daylight hours accounted for 33% of the time during days for which we could estimate time of killing, but wolves killed only 9% of their prey during daylight, which was less than expected).
Wolves were active and moved 1.7 + or - 0.2 h before they made a kill. Accordingly, hourly activity and distance traveled by wolves were highest during the 2 h before a kill. Distance traveled dropped immediately after wolves made a kill, but wolves remained mostly active and moved short distances in the hour after a kill. We compared activity and movement of wolves the day before a kill with the day after for 2 parts of the day. From evening to morning (3 h before sunset to 3 h after sunrise), wolves were less active and traveled shorter distances the day after a kill compared with their activity and distance traveled the day before the kill. However, in the middle of the day (3 h after sunrise to 3 h before sunset), wolves did not reduce their activity or movement. Length of active and inactive bouts did not differ between the days before and after a kill.
Breeding season.-Wolves were least active and mobile during the period of raising young (April-July). Activity and movement were highest in August and in February and March during the mating season. Breeding females reduced their activity and movement at night during the period of denning compared with nonbreeding females but not from dawn to dusk. The 1 adult male that we radiotracked during the denning period was no more active but traveled longer distances than did the breeding females. Breeding females stayed near the den 67 + or - 4% of the time during the 8-week-long denning period. Breeding females were the least active and mobile during the first 2 weeks after birth.
In the postdenning period, time active and distances traveled by breeding females increased compared with those of nonbreeding females. From dawn to dusk, breeding females moved even more than did nonbreeding females. In the postdenning period, activity and distance traveled by breeding females were not significantly higher than those of the male. During the rest of the year, activity and distance traveled by breeding females did not differ from those of nonbreeding females or males.
Weather. Wolves reduced their mean activity from 44.1 + or - 1.4% on days with no or light rain . Simultaneously, they reduced their movement...and length of their activity bouts....In contrast, activity and distance traveled by wolves were not different on days with and without snowfall. However, wolves decreased time active by 0.6% and distance traveled by 0.02 km/h for every centimeter of increasing snow depth for snow depths of 1-63 cm.
We tested the influence of extreme weather conditions (high and low temperatures, heavy rainfall, heavy snowfall, and deep snow) on daily patterns of wolf activity, but the animals only significantly modified their activity patterns on days when mean daily temperatures were > or =20[degrees]C. On such warm days, wolves reduced their movement from that on cooler summer days (10-19[degrees]C from May to August) during the evening (1800-2400 h). In the morning (0400-0800 h), differences in movement rates...were not significant.
Wolves in Europe had to adapt to [more than] 1,000 years of heavy persecution by humans, whereas they were hunted intensively during shorter periods in many areas of North America. If wolves adapted their behavior to avoid direct contact with humans, they might have become less active during the day. Indeed, wolves studied in mountainous agricultural regions of Spain and Italy with human densities of 20-30 inhabitants/km hardly moved during daylight. In Alaska, where human density is low, wolves moved during 50% of the daylight. In forests of Minnesota, where human density in the wolf range was 1.5 inhabitants/km, wolves moved during 28% of the daylight in winter. In the...Forest, persecution does not seem to have caused wolves to reduce their activity and movement in daylight, perhaps because our study area is mostly covered by forest. In Italy and Spain, where [less than] 40% of the area in the wolves' home ranges was forested, there may not have been enough cover for daylight movement. Human activity therefore does not seem to significantly influence temporal activity patterns of wolves in regions where they have the opportunity to avoid direct contact with humans. Our hypothesis that wolves would adapt their activity patterns to human activity was insufficient to explain behavior of wolves in our study area. We suggest that humans and wolves are spatio-temporally separated; i.e., wolves do not change their temporal activity patterns under human influence, but they avoid being in the same place at the same time as humans. In Romania, a wolf pack regularly visited a dump site at night in a town of 300,000 inhabitants but remained in the forest in the day.
There may have been other reasons why wolves reduced their activity and movement during the day. On warm days, wolves in our study area moved less in the evening but more in the morning, when ambient temperatures were usually lowest. Mech (1970) reported that wolves quickly get overheated in summer and usually reduce their daylight movement. Temperature may therefore have partly caused the nocturnal activity patterns of the wolf radiotracked in Italy from June to November by Ciucci et al. (1997). Human influences, however, can act indirectly through prey. Ungulates under human hunting pressure often reduce their daytime activity, which could drive wolves to be more nocturnal and hunt more at night than they would in areas without human activity. Although it is possible that human activity caused the nocturnality of wolves in Spain and Italy, the influence of humans may be confounded with factors such as temperature and prey activity. It is therefore difficult to clearly determine the effect of human activity on the temporal patterns of wolf activity.
In our study, the number of prey taken by wolves was highest when light was dim, i.e., at dawn, dusk, and on moonlit nights. Vision of canids is best adapted to daylight and the phase between day and night. Wolves that are kept in enclosures and do not have to hunt are almost exclusively active during daylight (Kreeger et al. 1996). We therefore think that the crepuscular and nocturnal activity of wolves is probably caused by the need to hunt. We suggest that dim light provides the best hunting chances for wolves and that prey are more readily available during this period. Red deer (C. elaphus) in the...Forest are active throughout the day with a tendency to activity peaks at dawn and dusk.
Peaks in activity and, especially, movement of wolves were closely related to the hunting pattern, and after a successful hunt, wolves reduced their activity. However, wolves did not decrease their activity and movement in the middle of the day after a kill in comparison with the day before a kill. This time may be used to eat, socialize, play, or keep diurnal scavengers such as ravens away from their kill.
During the period of reproduction, wolves (especially breeding females) spend much of their time at denning and rendezvous sites. Because other wolves from the pack usually assure the feeding of breeding females during this time, females do not have to maintain an activity pattern based on hunting. In our study, breeding females reduced their activity and movement at night during the denning period, which indicated that other wolves may have provided them with food. If other wolves cannot supply the breeding female with enough food, her activity pattern should be shaped both by hunting and by the need to attend pups. In Spain, such a situation caused breeding females to leave the den mainly in the day, whereas they were mainly active at night in other periods of the year. Vila et al. (1995) assumed that in Spain, where packs are usually small, it would be the safest for females to leave the den for hunting during the day when sunlight would help keep the unattended pups warm and potential predators are less active. Activity patterns of breeding females therefore seem to depend greatly on the ability of other pack members to provide them with food.
We conclude that daily activity patterns of wolves in our study area were mainly shaped by their pattern of hunting prey. Human activity appeared to have no significant influence on temporal activity patterns of wolves. The influence of humans may be indirect if hunters of ungulates modify the activity patterns of the wolves' prey. Rearing of young had a temporary influence on activity patterns and length of time active. Weather markedly modified behavior of wolves only under extreme situations such as high temperature and heavy rain. Although information on daily activity patterns of wolves has been gathered, it is still not possible to completely explain activity patterns of wolves in different sites.
Table 1: Activity of wolves during different parts of the day in the ... Forest, 1994-1999, as shown by time active, time moving, distance traveled (n = 11 wolves), and duration of activity (n = 5 wolves with activity sensors).
Table 2: Time active and distance traveled by breeding female wolves compared with nonbreeding females in the ... Forest, 1994-1999, during the denning and postdenning periods, at night and from dawn to dusk (including the day). Mean time active and distance traveled by breeding (n = 5) and nonbreeding females (n = 2) were compared by a t-test (d.f. = 5).
Figure 1: Daily patterns of mean time active and distance traveled by 11 wolves for periods of 2 months in the ... Forest (Poland), 1994-1999.
Figure 2: Patterns of mean time active and distance traveled by 11 wolves in relation to sunrise and sunset in the ... Forest, 1994-1999.
Figure 3: Daily patterns of mean time active and distance traveled by wolves compared with patterns of mean time with human presence in home ranges of the National Park pack (4 wolves), Ladzka pack (3 wolves), and Lesna packs (4 wolves) in the ... Forest, 1994-1999.
Figure 4: Temporal distribution of 54 wolf kills in the ... Forest, 1994-1999, shown as a) time of day and b) time relative to sunrise and sunset.
Figure 5: Mean time active and distance traveled by 10 wolves 24 h before and after time of 54 kills in the ... Forest, 1994-1999.
Figure 6: Monthly means of time active and distance traveled by 11 wolves in the ... Forest, 1994-1999.