Article,
The ecology of human-carnivore coexistence
Proceedings of the National Academy of Sciences, (2020)
DOI: 10.1073/pnas.1922097117
Abstract
The persistence of large carnivores in human-dominated landscapes will become increasingly challenging as the human footprint expands. Here, we bring together long-term demographic and behavioral data on one of the worlds’ most conflict-prone species, the brown bear, to quantify the mechanisms facilitating human–carnivore coexistence. We found that human-dominated landscapes are highly lethal, especially to young bears, until they learn to adapt to people. As bears age, they avoid times when people are most active but do not strongly avoid where people live. To sustain human–carnivore coexistence under high rates of mortality requires the influx of animals from areas with low human presence (i.e., demographic rescue). Paradoxically, our work demonstrates that connectivity leads to both coexistence and conflict.With a shrinking supply of wilderness and growing recognition that top predators can have a profound influence on ecosystems, the persistence of large carnivores in human-dominated landscapes has emerged as one of the greatest conservation challenges of our time. Carnivores fascinate society, yet these animals pose threats to people living near them, resulting in high rates of carnivore death near human settlements. We used 41 y of demographic data for more than 2,500 brown bears—one of the world’s most widely distributed and conflict-prone carnivores—to understand the behavioral and demographic mechanisms promoting carnivore coexistence in human-dominated landscapes. Bear mortality was high and unsustainable near people, but a human-induced shift to nocturnality facilitated lower risks of bear mortality and rates of conflict with people. Despite these behavioral shifts, projected population growth rates for bears in human-dominated areas revealed a source-sink dynamic. Despite some female bears successfully reproducing in the sink areas, bear persistence was reliant on a supply of immigrants from areas with minimal human influence (i.e., wilderness). Such mechanisms of coexistence reveal a striking paradox: Connectivity to wilderness areas supplies bears that likely will die from people, but these bears are essential to avert local extirpation. These insights suggest carnivores contribute to human–carnivore coexistence through behavioral and demographic mechanisms, and that connected wilderness is critical to sustain coexistence landscapes.
