Summer Drought May Increase Human-Bear Interactions
By mapping where human-bear interactions are most likely to occur under normal and drought conditions in Maryland, National CASC research can help wildlife managers support coexistence.
For some, encountering a bear in the wild can inspire awe and spark excitement. For others, it can be plain frightening. More likely, it’s some uneasy combination of emotions, determined in part by how close the bear is and whose habitat it is perceived to be. As encounters with bears increase nationwide, understanding when, where, and why they occur can help wildlife managers prepare communities to safely coexist with bears.
A new publication, a collaboration between the National CASC and the Maryland Department of Natural Resources, shows that summer drought may increase the risk of negative interactions between humans and American black bears in Maryland and expand the areas where encounters are likely to occur.
Negative interactions happen when conflicting goals or actions make it difficult for humans and bears to coexist, resulting in harmful consequences for people, bears, or both. These incidents can range from bears entering properties and buildings to accessing human food sources or damaging crops.
In the study, the authors examined 840 negative interactions reported in Maryland across four years, from 2020-2023. They then evaluated 15 human-related and environmental factors associated with the reports to better understand the conditions and locations where these interactions occur.
The findings reinforced some of what was expected: human-bear interactions were more likely in locations where bear habitat and human activity overlap. Elevation and distance to large forest patches were among the strongest predictors of interaction risk, along with proximity to roads, parks, and human development. Most of the 840 reported incidents involved property encroachment, attractants, and vehicle collisions.
The researchers also found that summer drought was an important factor. When drought is absent, areas of elevated interaction risk were concentrated near population centers in the more mountainous western Maryland. During and after summer drought, however, predicted risk intensified and expanded into new areas. Drought lowers the availability of natural food sources for bears, which may push them to seek alternative food sources closer to people, often from birdseed or garbage bins. Although climate and weather are known to strongly affect bear food supplies and habitat, the role of climate in driving human-bear interactions is relatively understudied.
The study also revealed seasonal patterns, with reports peaking in June, when bears are particularly active moving across landscapes in search of mates and resources.
Maryland’s mix of urban and rural landscapes brings people and black bears into close contact, and the state ranks high nationally in reported interaction incidents per 10,000 people. With droughts expected to remain a recurring feature of Maryland summers that could potentially worsen in the future, identifying areas more prone to interactions can help wildlife managers anticipate incidents, direct resources to help prevent their occurrence, and reduce conflict.
This work was supported by the National CASC project “The Effects of Climate Variability and Change on Human-Bear Interactions in North America.”
Read the paper: “Using advanced machine learning to evaluate the spatial and temporal patterns of human-bear interactions in Maryland, USA” published in the journal Human-Wildlife Interactions.