Albuquerque's Cooper's hawks face a surprising array of threats despite legal safeguards, according to a new study published in the Journal of Raptor.
Researchers with the U.S. Fish and Wildlife Service attached GPS transmitters to 158 female Cooper's hawks over 11 years. Sadly, 88 of the birds died during the study.
The leading cause of death? Collisions with human-made structures. Windows, fences, power lines, and even building ductwork were responsible for the demise of 52 hawks. Even more concerning was the discovery that humans deliberately killed 8 of the tagged birds.
"The amount of human persecution that we observed was surprising," said lead researcher Brian Millsap. "We thought the days of widespread raptor killings were over, but this study suggests otherwise."
The study highlights the limitations of traditional methods for tracking raptor deaths, which often rely on finding injured or deceased birds. GPS transmitters provide a more complete picture, regardless of how the bird perished.
The researchers also investigated how age and season impacted survival rates. Young hawks, in their first four months of independence, were especially vulnerable, likely due to inexperience in hunting and avoiding dangers. Their survival rate jumped by 55% after making it through this initial period.
Disputes over territory and mates were the most common cause of death during the pre-breeding season for both young and adult hawks.
The study also revealed troubling evidence of secondary poisoning from rodenticides. These toxins build up in the bodies of prey animals, ultimately reaching high concentrations in top predators like Cooper's hawks. Public education on the responsible use of rodenticides is crucial to address this threat.
The research team received positive feedback from Albuquerque residents. "Everyone from homeowners to city workers have been interested in our work," said Millsap. "This public support has been essential to the study's success."
Future research will focus on male Cooper's hawks to determine if there are sex-based differences in mortality rates.
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