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People are a greater threat to wildlife than climate change or anything else

In our local neighborhoods, encountering distressed wildlife is not uncommon. People often turn to social media seeking advice on what to do when they find injured or disoriented wildlife. The answer typically lies with local wildlife rehabilitation centers.

These centers, run by licensed individuals and organizations, play a crucial role in caring for sick and injured wildlife. They handle hundreds of thousands of wild animals annually across the United States, offering a unique perspective on animal health and environmental changes.

Studying how humans impact wildlife

A few years ago, Tara Miller, a biologist then with Defenders of Wildlife, came across Wendy Hall, cofounder of the Adirondack Wildlife Refuge. Hall shared observations about unusual animal occurrences, like the appearance of black vultures, typically a southern species, in the Adirondacks.

These insights, linked to climate change, sparked Miller’s interest in using wildlife rehabilitation data to study the environmental impact on North American wildlife.

Miller, who uses they/them pronouns, spearheaded a pioneering study while at Boston University’s Urban Biogeoscience and Environmental Health program. Collaborating with 94 wildlife centers across the U.S. and Canada, Miller’s team analyzed records of over a thousand species. This study aimed to identify regional threats to wildlife and assess the effectiveness of rehab centers in treating these animals.

What the research team learned

The research revealed alarming trends. Human activities, such as lead poisoning in bald eagles and sea turtles entangled in fishing gear, have a significant impact on wildlife.

The study also noted an increase in animals admitted to rehab centers following extreme weather events, a phenomenon linked to climate change. Miller emphasizes the importance of their findings in understanding the broader, direct impact that people have on wildlife.

“A lot of what we found in the research isn’t going to shock anyone, but you want to be able to tell people, ‘It’s not just this one animal. This is happening across the country,’” Miller says. “I think that was what was so cool about the work we were able to do with this huge dataset: tie together what rehabbers across the country are seeing and validate it. We were able to find a lot of these trends for the big picture of how humans are impacting wildlife.”

Data collection and challenges

Initially, accessing wildlife rehab records was a challenge, as most were stored in physical formats. However, with digitalization efforts, like the Wildlife Center of Virginia’s WILD-ONe patient database system, researchers could analyze vast amounts of data. This system also plays a role in identifying wildlife diseases that might affect human and livestock health.

“This was a gigantic dataset, with more than 600,000 observations,” says Richard Primack, a BU College of Arts & Sciences professor of biology, who was Miller’s PhD advisor and a coauthor on the paper. Primack says he encourages all of his students to consider what questions they want their data to address. In Miller’s case, the big question was, “What are the major threats to wildlife?”

Miller’s interactions with wildlife rehabilitators were integral to the study. These conversations often happened amidst the rehabbers’ busy schedules, highlighting their dedication and willingness to contribute to the project.

“I had phone calls with rehabbers where they would have to jump off because they had a baby squirrel they had to go feed, or one time someone had a porcupine autopsy they had to get back to,” Miller says. “People were so generous with their time and of their data, and so enthusiastic about this whole project.”

People threaten wildlife in many ways

The data showed that human disturbances caused injuries to 40% of the animals admitted to rehab centers. These disturbances included vehicle accidents, building collisions, and fishing incidents.

Miller, in a tone of incredulity, noted, “Forty percent of the animals arrive at wildlife rehab centers largely due to negative impacts from human activities. How can we modify our policies and behaviors to lessen our impact on these animals?”

Regarding seasonal trends, the researchers found that vehicle collisions, peaking from May to July, affected reptiles disproportionately. During spring, summer, and early fall — periods of heightened agricultural and construction activities — pesticide poisonings rose.

In the winter, following the hunting season, lead poisonings became more prevalent, especially in animals like bald eagles. This increase is often due to many hunters using lead ammunition for deer hunting. Lead from the bullets subsequently poisons scavengers like eagles and vultures feeding on the remains.

Future policy and environmental health

Wildlife rehab centers eventually release about one-third of the animals they receive back into the wild. However, this release rate varies significantly among different species.

“For example, pelicans are injured but then are often released [68%], whereas bald eagles have a very low chance of being released [20%],” Primack says. “This presents a very interesting question of why the threats to wildlife are so different between these two groups of large birds.”

The team hopes their research will aid wildlife rehab centers in securing grants and funding. It also aims to encourage community-level changes to protect wildlife from people. Their plans would include implementing wildlife underpasses and overpasses, using bird-friendly window designs, and promoting the use of non-lead fishing gear and ammunition.

Post-graduation, Miller has shifted focus to policy research at the University of Virginia, addressing environmental health issues affecting human communities. This transition underscores the interconnectedness of wildlife and human health and the broader environmental impacts of policy decisions.

In summary, this study, led by Tara Miller, marks a significant step in understanding the threats facing wildlife and the role of human activities in these challenges. It calls for a collective effort in policy-making, community awareness, and individual actions to create a safer environment for wildlife and, consequently, for ourselves.

The full study was published in the journal Biological Conservation.

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