CHAMPAIGN, Ill., 11/18/19: Owls have never been known as scavengers that eat decaying flesh, but the behavior is more widespread than once believed, according to University of Illinois researchers at the Illinois Natural History Survey (INHS) who photographed owls scavenging in the night.
“Going back decades, scavengers were considered rare and only included certain species, such as hyenas and vultures,” said INHS wildlife ecologist Max Allen. “We’re now discovering that most things that eat meat also scavenge.”
Allen and colleagues documented instances of owls scavenging in the United States and in Europe and studied previous journal articles. Findings showed that the most common owls observed were large species, such as the great horned owl, Eurasian eagle owl, and snowy owl, and particularly those that lived in forests.
Most of the carcasses were mammals, especially hoofed animals, followed by birds and reptiles. In many cases, the carcasses were larger than the feeding owls themselves. For the direct observations in the study, the scientists used deer, rabbit, and racoon roadkill.
Half of the owls fed on carcasses in winter, and nearly half during the breeding season in summer.
Historically, owl diets have been studied by examining owl pellets containing fur, bones, teeth, and other undigestible parts. When owls mainly eat meat from a carcass, pellets may not show any remnants to identify a deer or other animal.
Another challenge is that when observing an owl with a squirrel in its talons, it would be difficult to determine if the owl killed the squirrel or picked up a dead animal from the forest floor.
Using cameras to catch owls in the act has improved the scientific understanding of how owls feed.
“Camera traps have changed how we view behaviors that have rarely been seen,” Allen said. “We are able to document behaviors that we were not able to document before. We can observe that owls really do scavenge, but we don’t have enough data to tell us when and why.”
One surprising observation was that owls fed on carcasses for a relatively short time but did not return later for another bite. One explanation is that the owls ate their fill in one sitting, Allen said.
Another reason may be the natural pecking order of scavengers in the wild, according to INHS avian ecologist Mike Ward. Coyotes and larger birds pose a threat to feeding owls.
“Owls may take advantage of a carcass nearby, but they may not return later for fear that an animal or bird larger than themselves will be in the area,” Ward said. “Owls are tough birds, but they’re not the top bird when it comes to the pecking order.”
The study was published in the Journal of Raptor Research.
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Media contact: Max Allen, 217-300-7674, maxallen@illinois.edu; Mike Ward, 217-244-4089, mpward@illinois.edu