Individual Effects of Seasonal Changes,Visitor Density,and Concurrent Bear Behavior on Stereotypical Behaviors in Captive Polar Bears (Ursus maritimus)

Stereotypical behaviors in captive polar bears (Ursus maritimus) can be detrimental to their welfare. These behaviors can be reduced through enrichment programs but are often not completely eliminated, so identifying potential triggers is important. The present study investigated the influences of seasonal changes, visitor density, and concurrent bear activity on stereotypical behaviors exhibited by 3 captive polar bears at the Toronto Zoo. All bears exhibited these behaviors; however, individual differences were found in duration and form. The male exhibited less stereotypical behavior during spring, and the females exhibited less stereotypical behavior during winter. An increase in visitor density was associated with more stereotypical behavior in 1 female but less stereotypical behavior in the other 2 bears. All bears engaged in more stereotypical behaviors when the other bears were inactive, and 1 female engaged in more stereotypical behaviors when the other bears were out of sight. Further, when conspecifics were active, all bears engaged in less stereotypical behaviors. Given the variability among individual bears, future enrichment programs must be tailored to the needs of individuals to maximize efficacy.     

EFFECTS OF FASTING AND FEEDING ON SERUM UREA AND SERUM CREATININE LEVELS IN POLAR BEARS

Polar bears were held in captivity and fasted for an average of 38 d prior to being fed for three days. Blood samples were collected prior to feeding and then at one and three days post-feeding in 1984 and at one, four, and seven days post-feeding in 1985. The ratio of serum urea to serum creatinine varied significantly in 1984, rising from a pre-feeding mean of 11.0 (SE = 2.6) to 32.0 (SE = 3.2) on the first day post-feeding and then dropped to 22.8 (SE =3.2) in the last sample. In 1985, the ratio of serum urea to serum creatinine increased from a pre-feeding mean of 15.8 (SE = 2.3) to 61.2 (SE = 10.6) after three days of feeding and dropped to a mean of 29.2 (SE = 5.1) seven days after feeding ended. Serum urea levels varied over the study period in both years. No significant variation in serum creatinine levels was found in 1984, but in 1985, serum creatinine levels demonstrated significant variation, declining from the pre-feeding mean of 1.83 mg/dl (SE = 0.29) to 0.96 mg/dl (SE = 0.12) in the last sample.
The findings suggest that polar bears can have a low serum urea to serum creatinine ratio, similar to that found in hibernating black bears, or higher ratios after feeding. Polar bears can rapidly return to a fasting serum urea to creatinine ratio after food is withheld. Polar bears may demonstrate urea conservation, similar to that found in black bears, and may be able to move between a fasting and a feeding metabolism based on food availability throughout the year, an adaptation to life on the labile sea ice.     

Temporal change in the morphometry–body mass relationship of polar bears

Accurate information on animal body mass is often an essential component of wildlife research and management. However, for many large-bodied species, obtaining direct scale weights from individuals may be difficult. In these cases, morphometric equations (e.g., based on girth or length) may provide accurate and precise estimates of body mass. We developed predictive equations to estimate the body mass of free-ranging polar bears (Ursus maritimus) in western Hudson Bay, Canada. Using multiple linear and non-linear regression, we identified a strong relationship between polar bear body weight and linear measures of straight line length and axillary girth. The mass–morphometry relationship appeared to change over time and we developed separate equations for polar bears measured during 2 time periods, 1980–1996 and 2007–2009. Non-linear models were more accurate and provided body mass estimates within 5.8% (R² = 0.98) and 6.1% (R² = 0.98) of scale weight in the earlier and later time periods, respectively. Earlier equations developed for polar bears in this subpopulation performed poorly when applied to recently sampled individuals. In contrast, some contemporary equations from other regions performed reasonably well, suggesting that temporal changes within a subpopulation may be more pronounced than regional differences and can render earlier predictive equations obsolete. Our results have important implications for current and future studies of polar bear body condition and the effects of ongoing climate warming. © 2011 The Wildlife Society.     

Determinants of Home Range Size for Polar Bears (Ursus maritimus)

The mean home range size of female polar bears ( Ursus maritimus ; 125 100 km² ± 11 800; n  = 93) is substantially larger than the predicted value (514 km²) for a terrestrial carnivore of similar weight. To understand this difference, we correlated home range size and sea ice characteristics. Home range size was related to (i) the ratio of land vs. sea within a given home range (42% of explained variance), and (ii) seasonal variation in ice cover (24%). Thus, bears using land during the ice-free season had larger home ranges and bears living in areas of great seasonal variation in ice cover also had larger home ranges. In another analysis we investigated how variation in a bear's environment in space and time affects its choice of home range. We found that polar bears adjusted the size of their home range according to the amount of annual and seasonal variation within the centre of their home range. For example, polar bears experiencing unpredictable seasonal and annual ice tended to increase their home range size if increasing home range size resulted in reducing variation in seasonal and annual ice. Polar bears make trade-offs between alternate space-use strategies. Large home ranges occur when variable ice cover is associated with more seals but also a more unpredictable distribution of those seals.     

Use of foraging racks and shavings as enrichment tools for groups of rhesus monkeys (Macaca mulatta)

Searching for and processing food are important activities of free-ranging primates. In contrast, captive primates spend little time foraging. Their food is readily available, easily obtained, and can be consumed quickly. The present study compared the use of foraging racks and a shavings substrate as two manipulations used to alter feeding behavior in nonhuman primates. Each method was tested in between two baseline periods (no racks or shavings present). Behavioral data were collected using a 30-sec scan sampling procedure for 1 hr during the feeding period. Both the rack conditions and the shavings condition decreased passive feeding behavior in the subjects. The use of racks also resulted in increased cage usage, activity, and movement, and decreased social proximity; the use of shavings resulted in decreased agonism. This study suggests that foraging racks and shavings are useful devices for environmental enrichment. © 1995 Wiley-Liss, Inc.     

The breeding of great apes at the Jersey Wildlife Preservation Trust and a look into the future

Details of breeding orangutans and gorillas at the Jersey Wildlife Preservation Trust are reviewed, with special reference to the diversity of managerial requirements and reproductive parameters for the two species of great apes represented. The importance of recording and publishing as much data as possible to provide important guidelines for others involved with the same or related species in captivity, as well as such information contributing directly to conservation in the wild, is underlined. The Jersey Trust's involvement with cooperative and coordinated breeding programs for the two species on both a national and international basis is reported, and prospects for future long-term management strategies are outlined.     

What to eat now? Shifts in polar bear diet during the ice-free season in western Hudson Bay

Under current climate trends, spring ice breakup in Hudson Bay is advancing rapidly, leaving polar bears (Ursus maritimus) less time to hunt seals during the spring when they accumulate the majority of their annual fat reserves. For this reason, foods that polar bears consume during the ice‐free season may become increasingly important in alleviating nutritional stress from lost seal hunting opportunities. Defining how the terrestrial diet might have changed since the onset of rapid climate change is an important step in understanding how polar bears may be reacting to climate change. We characterized the current terrestrial diet of polar bears in western Hudson Bay by evaluating the contents of passively sampled scat and comparing it to a similar study conducted 40 years ago. While the two terrestrial diets broadly overlap, polar bears currently appear to be exploiting increasingly abundant resources such as caribou (Rangifer tarandus) and snow geese (Chen caerulescens caerulescens) and newly available resources such as eggs. This opportunistic shift is similar to the diet mixing strategy common among other Arctic predators and bear species. We discuss whether the observed diet shift is solely a response to a nutritional stress or is an expression of plastic foraging behavior.     

Trends in intensive management of Alaska's grizzly bears, 1980–2010

Hunting regulations for grizzly bears (Ursus arctos) in much of Alaska since 1980 increasingly were designed to reduce bear abundance in the expectation such regulations would lead to increased harvests by hunters of moose (Alces alces) and caribou (Rangifer tarandus). Regulations were liberalized during 1980–2010 primarily in the area we termed the Liberal Grizzly Bear Hunting Area (hereafter Liberal Hunt Area) which encompassed 76.2% of Alaska. By 2010, these changes resulted in longer hunting seasons (100% of Liberal Hunt Area had seasons > 100 days, 99.7% > 200 days, and 67.8% > 300 days), more liberal bag limits (99.1% of the Liberal Hunt Area with a bag limit ≥ 1/yr and 10.1% with a bag limit ≥ 2/yr), and widespread waiver of resident tag fees (waived in 95.7% of the Liberal Hunt Area). During 1995–2010, there were 124 changes that made grizzly bear hunting regulations more liberal and two making them more conservative. The 4-year mean for grizzly bear kills by hunters increased 213% between 1976–1980 (387 grizzly bears) and 2005–2008 (823 grizzly bears). Since 2000, long-term research studies on grizzly populations in the Liberal Hunt Area have been terminated without replacement. Management of large predators by the State of Alaska is constrained by a 1994 state statute mandating “intensive management” in areas classified as important for human consumptive use of ungulates. Current grizzly bear management in the Liberal Hunt Area is inconsistent with the recommendations of the National Research Council's 1997 report on predator management in Alaska. Current attitudes, policies and absence of science-based management of grizzly bears in Alaska are increasingly similar to those that resulted in the near extirpation of grizzly bears south of Canada in the 19th and 20th centuries. If current trends continue, they increase risks to portions of the largest and most intact population of grizzly bears in North America. © 2011 The Wildlife Society.     

Behavior of captive-raised rattlesnakes (Crotalus enyo) as a function of rearing conditions

Two litters of rattlesnakes (Crotalus enyo; n = 6 per litter) were raised in large cages and small plastic boxes, respectively. No significant differences in exploration of a novel environment were observed between the litters, or between either of them and a group of wild-caught C. enyo, suggesting that the common practice of rearing baby snakes in small cages has no debilitating consequences on these measures. In the absence of differences between the litters, the two samples were pooled and additional analyses revealed the existence of reliable individual variation. Experiment 2 compared the two litters and the wild-caught snakes on measures of prey-directed behavior. The two captive-reared litters did not differ, but both exhibited lower levels of strike-induced chemosensory searching than did wild-caught snakes.