Following mass agricultural expansion and deforestation in the late 1800s and early 1900s, American black bear populations (Ursus americanus, hereafter black bear) were low across most of Virginia. The Department of Wildlife Resources (VADWR) and the United States Forest Service worked to rebuild wildlife habitat in the state, leading to recovery of bears. While some aspects of black bear hibernation and foraging ecology have been studied, there remain knowledge gaps on key aspects of black bear biology. Hibernation behavior, for example, is understudied with most knowledge stemming from post-hibernation emergence studies. We used a unique dataset with continuous monitoring of mother bears and their cubs from Virginia Tech's Black Bear Research Center in 2015-2016, to better understand hibernation ecology, mother-cub dynamics, and biological-foster cub dynamics. We found that increased black bear activity levels were driven by both higher temperature and photoperiod, but the onset of hibernation was primarily driven by only temperature. Temperature is projected to rise in VA and rising temperatures regionally could be responsible for increased active behaviors in bears, which could lead to increased human-black bear interactions on the landscape, especially during hibernation onset. We also found that mother bears spend similar amounts of time with biological and foster cubs. Biological cubs did not show more dominance behaviors toward fosters than biological siblings, which we also observed with foster, where they did not continuously display these behaviors towards biological cubs. These results are promising for orphan cub fostering programs in VA and other states and indicate that foster cub litter integration can be successful.
Foraging ecology also is challenging to study in black bears because direct observation is generally not possible due to their cryptic nature, closed habitat, or potential danger in observing. We used a dataset from camera collars deployed on 15 bears (8 males, 7 females) in Bath County Virginia in 2018 and 2019 to better understand diet seasonality and to determine habitat and environmental drivers of black bear foraging patterns, particularly on white-tailed deer (Odocoileus virginianus) and invasive plant species. We identified 178 unique diet items to family, genus, or species in videos, much higher numbers than previously reported in the literature, and we found high diet overlap between sexes. Diet composition was primarily influenced by season with higher levels of consumption of herbaceous soft mast in spring, fruit and seed soft mast in summer, and hard mast in fall. Females exhibited more hunting events on deer fawns in spring than males, but males and females consumed similar numbers (28 vs. 24, respectively) via hunting and scavenging combined. Males consumed anthropogenic foods more often than females, particularly when closer to human settlements and males more commonly consumed invasive plant species in spring while females more often consumed insect in spring invasive species in summer. Our results highlight strong seasonally- and subtle sex-mediated differences in black bear diets. We provide information on drivers of diet choices by bears, as well as identify where foraging hotspots on species of interest occur, providing information useful to VADWR in managing increased human-wildlife interactions (and mitigating potential for negative interactions), predator-prey relations, and invasive species spread across the landscape. / Master of Science / American black bears were almost eliminated from Virginia following mass agricultural expansion and deforestation in the late 1800s and early 1900s. The Department of Wildlife Resources (VADWR) and the United States Forest Service worked to rebuild wildlife habitat in the state, leading to recent recovery of bears in VA. However, there are still gaps in our knowledge of black bear ecology and gaining new knowledge will aid in better management of black bears across the state. We used two unique video data sets to study hibernation and foraging (or feeding) ecology to fill important knowledge gaps. To study hibernation behavior, we used a video data set of continuously monitored, temporarily captive mother bears and their cubs held at Virginia Tech's Black Bear Research Center in 2015-2016. We found that black bear activity was driven by both daily temperature and photoperiod (length of daylight), but onset of hibernation was mostly driven by temperature only. With Virginia projected to experience rising, and more variable, temperatures due to climate change, this may mean that bears will stay longer on the landscape in fall, even past the point where vegetation (food) has gone dormant, potentially leading to increased human-black bear interactions as bears seek human foods. We also examined mother-cub interactions and found mother bears did not spend more time with their biological cubs than their fosters (fosters are orphaned black bear cubs arising due to death of mothers) and biological cubs did not show more dominance behaviors (i.e., biting, chasing, or pinning to ground) toward fosters than biological siblings. These are positive results for VADWR's surrogate sow program across the state.
Foraging ecology is difficult to study in black bears because direct observation is generally not possible due to their secretive nature, dense habitat, or potential danger in observing. Therefore, traditionally, many studies collect and examine scat (fecal) samples or stomach contents from harvested bears, but these methods may not find diet items that are quickly digested. We used a unique dataset from video camera collars placed on 15 bears in Bath County Virginia in 2018 and 2019. We found some important differences from the literature - our spring diets had higher proportions of deer and soft vegetation (leaves), however the unknown diet items in the literature were high, leading to incomplete or incorrect diet profiles. Diet composition was primarily influenced by season with higher levels of consumption of leafy soft mast in spring, fruit and seed soft mast in summer, and hard mast in fall. Males and females had high dietary overlap and we found that females had more hunting events on deer fawns in spring than males, but overall males and females consumed similar numbers (28 vs. 24, respectively) via hunting and scavenging combined. Males more often consumed human foods than females, while females more often consumed insect species than males. Also, males more commonly consumed invasive species in spring, while females did so in summer. Our results highlight differences in diet content caused by season and subtle differences in diets between sexes. We provide information on drivers of feeding choices bears make and we identify foraging hotspots for deer and invasive species, information useful to VADWR in managing potential human-wildlife interactions, predator-prey relations, and invasive species spread across the landscape.
| Identifer | oai:union.ndltd.org:VTETD/oai:vtechworks.lib.vt.edu:10919/119358 |
| Date | 07 June 2024 |
| Creators | Holcombe, Brogan Elizabeth |
| Contributors | Fish and Wildlife Conservation, Kelly, Marcella J., Parkhurst, James A., Ford, William Mark, Mesa Cruz, Jose Bernardo |
| Publisher | Virginia Tech |
| Source Sets | Virginia Tech Theses and Dissertation |
| Language | English |
| Detected Language | English |
| Type | Thesis |
| Format | ETD, application/pdf |
| Rights | In Copyright, http://rightsstatements.org/vocab/InC/1.0/ |
Page generated in 0.0031 seconds