Changing Population Dynamics of Black Bears in Pennsylvania
A look into the changing populations of black bears due to human-mediated factors like hunting, conflict, or land use change.
A short history of black bear population dynamics
The black bear (Ursus americanus) is the smallest and most common type of bear found in North America out of the three bear species: black, brown, and polar bears (Falker and Brittingham, 1998). Only black bear can be found in Pennsylvania (PA), with upwards of 20,000 roaming across nearly all of the state currently (Wesser, 2023). The Pennsylvania black bear population has been increasing for decades. However, prior to the 1980s, excessive mortality rates of black bear were the reason behind the declining population. Overhunting for bear hides, meat, and grease, and because bears were perceived as threats to crops, livestock, and humans, led to a declining bear population in the late 1800s and early 1900s. In addition, bear habitats were being altered as humans converted forested lands to agriculture. Recovery efforts aimed at increasing the black bear population occurred in PA from 1980-2000. Since then, the black bear population in Pennsylvania has been increasing (Carrollo, 2024).
Population growth of black bears in PA
The black bear has increased substantially in PA from around 4,000 in the 1970s to around 18-20,000 today. The increase in bear and spread of their habitat range has caused more human-bear conflicts. As the population increases, so does hunting of these black bears. Almost three times as many hunters are harvesting bears today than 30 years ago.
Bear-human conflict is increasing as well as due to humans moving into bear territory as the bear population and range continues to grow. Human-bear conflicts include property, livestock, and agricultural damage, human injury, and other nuisances. This has resulted in legal action such as the 2003 regulation which makes it illegal to feed bears and an emphasis on education to teach people how to coexist with bears (PA Game Commission, 2024b). To decrease the black bear population, bear hunting season has been lengthened starting in 2002, but has remained within an acceptable rate to keep bear populations steady and safe (PA Game Commission, 2024b). Hunting types includes archery, muzzleloader, or special and regular firearms. Only one bear may be taken during the hunting license year with an official bear license (PA Game Commission, 2024d).
Another factor of population growth is that black bear, a large carnivore species with an opportunistic omnivorous diet, navigate fragmented landscapes fairly successfully because of their ability to travel long distances, diverse diet, skill at exploiting natural (small mammals, fruit or plants) and anthropogenic (human food waste) foods, and tolerance of humans. The hyper-abundance of anthropogenic food nowadays is a significant contributor to increased fitness and fecundity in black bears in the mid-Atlantic region (Nelson et al., 2024).
Public Interest
Since humans are moving into areas where bear live, and contact between black bears and humans are ever-increasing, learning about PA black bears and being aware of their habits, increasing habitat range, and increasing population is important for human safety and peaceful coexistence (PA Game Commission, 2024a). In addition, black bears are a valuable resource in PA that should be managed wisely because they are an indicator of ecosystem health and a source of recreation for hunters, wildlife photographers and people who enjoy wildlife (Carrollo, 2024). Bear conflicts influence how people value bears and impacts how wildlife programs divert their resources to improving how people view and value bears (Carrollo, 2024).
Most common bear nuisance problems are garbage can raids and bird feeder damage. However, conflict numbers vary geographically. This is not fully due to the increasing bear numbers, but because bear range is increasing near suburban areas while more people are also moving into areas traditionally occupied by bears. In addition, people moving into black bear’s range have no experience coexisting with these bears. It is important that people learn to report only significant or impactful bear conflicts because one way the PA Game Commission reduces conflicts is by removing (translocating or euthanizing) bears involved in conflicts (Carrollo, 2024).
The map below shows bear check stations located across the state. The Pennsylvania Game Commission operates ~25 bear check stations during the 4-day firearms hunting season for bear. Bear hunters are required to bring any bear they kill to one of the bear check stations within 24 hours of making the kill to get it tagged, weighed, and sexed. These check stations allow the state to maintain statistics for use in Pennsylvania's bear management program (Schneck, n.d.). The dark green patches are state game lands. The map is split up by PA's wildlife management unit boundaries which are used to manage all game in the state and are based on habitat and human-related land characteristics (Pennsylvania Game Commission, 2024e).
Bear check stations (in relation to PA's wildlife management units and state game land)
Management
All wildlife populations have a threshold where increasing abundance begins to negatively impact habitats, reproduction, and survival. Therefore, the Bureau of Wildlife Management of the Pennsylvania Game Commission issued a 5 Year Plan Revision for Management and Biology of Black Bears in Pennsylvania. This plan aims to meet four goals: ensure that black bear populations remain sustainable, maintain diverse forested habitats throughout the state for black bear, maintain human bear conflicts at acceptable levels, provide recreational opportunities that involve black bear, and increase the public’s knowledge about black bear (Carrollo, 2024).
The map below show the black bear range (light green) and habitat range (dark green). This gives us better insight into where bears roam across the state and the habitat areas they prefer to live in. The map shows that bears live in more rural and less densely populated areas.
Black bear range and habitat map
Mortality & Harvest
Most black bear mortality in Pennsylvania is caused by human activities. The leading cause of bear death is hunting. Other forms of mortality caused by humans include vehicle collisions, being shot for crop damage, poaching, and removal of bears deemed dangerous to the public (Carrollo, 2024).
The map below illustrates harvest numbers in PA by county. The darker red counties indicate higher black bear harvest. The map shows what counties in PA have dense harvests. Pennsylvania’s bear hunting seasons are currently managed to harvest 20% of the bear population annually. Pennsylvania Game Commission reports that, "in 2004, hunters took 2,972 bears from 53 counties. Then, in 2011, a record harvest of 4,350 bears occurred, which remains today the largest kill on record" (PA Game Commission, 2024b). A comparison of 2004 and 2011 harvest records by county are shown in the map below. The counties with the highest harvest are in the northcentral part of the state, namely Clinton, Lycoming, Potter, and Tioga counties (Pennsylvania Game Commission, 2024c). High harvest rates in northcentral PA coincides with bear's habitat range being dense in central PA as shown in the map above.
Bear Harvests 2004
Bear Harvests 2011
Hunting Consequences
Hunting has consequences for the environment. For example, most hunters use lead (Pb) ammunition that shed metal fragments in the tissues of harvested animals. These Pb fragments become available to scavengers when contaminated slaughter remains are left in the environment. In addition, any intake of PB is toxic, and affects the bears as well. This is important to note because as hunting increases to manage the bear population, lead exposure becomes more prominent in the environment (Brown et al., 2022).
Lead exposure pathway (Brown et al., 2022)
Anthropogenic Pressures
Anthropogenic pressure like urbanization, habitat loss, and climate change is felt more severely by large mammals like bears than other species, because of their higher energetic requirements, larger home ranges, lower fecundity, and longer generation times. These anthropogenic pressures diminish bear’s viability and alter ecosystem function by suppressing their role as an apex predator (Nelson et al., 2024).
Disease
In addition, diseases like the protozoan Toxoplasma gondii and the metazoan Trichinella spp., which infect warm-blooded animals, have the highest prevalence among black bears in the USA. Since 75% of black bear’s diet is plant matter, bears act as an indicator for environmental contamination with T. gondii, and their meat scavenging activities provide an indicator of the level of Trichinella spp. (Dubey et al., 2016). Monitoring these disease levels in black bears is key to their survival and to manage the spread of disease in the environment.
Conclusions
Overall, the Pennsylvania black bear population is greatly influenced by humans. Human's put pressure on bears and their environment by spreading disease, causing environmental lead contamination, increased human-bear conflict (due to increasing rates of close-contact), and by exploiting bears for economic benefits (hides, big-game hunting value, and as signifiers for pristine environment). At this time, the PA Game Commission is mainly responsible for the management of black bears in PA. Therefore, it is important to take time to analyze the changing black bear population and its habitat ranges to best understand what is the most sustainable outcome for both humans and bears to co-exist in this state together.