Science

Watch: Female Hog Island Osprey Defends Remaining Chick From Great Horned Owl

Having already lost two chicks to the raptor, Rachel has been remaining close to the nest and on high alert in a fascinating display of adaptation.
By Andrew Del-Colle
Digital Editorial Director, 探花精选 Magazine
Published July 21, 2017

It's been a dramatic two weeks for Rachel and Steve's family. Early last week听a Great Horned Owl attacked in the middle of the night听and took a chick from the Osprey couple's nest at 探花精选's Hog Island in Maine. Then, a few nights听later, it returned for seconds. Even for a nest cam听that has captured听its听share of nest attacks and 丑颈蝉迟辞谤颈肠听尘辞尘别苍迟蝉, this has been an especially eventful听12听days.听

Since the听attacks,听viewers of the cam, which is hosted by 听have been anxiously听watching to see if the owl would strike听again and听Rachel would be able to protect the lone remaining chick听(as noted in our story about the first attack, male Ospreys don't usually defend their nests听at night). In response to the attacks,听Rachel has stuck closer to the nest, and that paid off last night听when听presumably the same听Great Horned Owl returned for round three.听This听time, though,听Rachel was ready.听

As can be听seen in the video above, the clip opens up almost right听away with an attempted听attack that Rachel manages to thwart. Then, at the 2:57 mark,听the Great Horned Owl appears in the background, landing听in the bough of an evergreen to听survey the situation. After a full minute, it takes wing again, disappearing from view. Rachel, who is sitting on the edge听of the nest,听clearly spots the bird, though, as she begins loudly emitting her warning calls. The owl swoops in anyway and attempts to land on a large limb sticking out from the nest, only to be chased away. Undeterred, the owl returns again at 5:45听for one more attempt. But Rachel digs her talons into its back and once again defends the nest.听It's not clear if the chick was harmed during the听attacks, but it at least got to survive听to see another Hog Island sunrise.听

While it's been captivating to watch this saga play out,听Rachel's听adaptations to the attacks are illuminating听in an听evolutionary and biological听sense. We听once again asked听Steve Kress, who works on Hog Island and is 探花精选's听vice president of conservation and听director of听seabird restoration program, for his thoughts on this latest news. Here's what he wrote back in an email:听

"There is a lot of insight about how individual predators learn new and ingenious ways to capture prey.听What is surprising here is that Rachel seems to be learning new ways to defend her remaining chick. Predator-prey interfaces are often thought to be driven by selection favoring specific behaviors that then become genetically hard-wired, but if Rachel is changing her behavior by perching lower and closer to her chick, it appears she is learning from her experience and adapting her behavior to be a more successful parent. The camera is once again showing new and very exciting insight to bird behavior."听
Considering the owl clearly realizes that there's one remaining听meal in this听nest, there's a good chance that this isn't the last time Rachel will have to fight it off.听However, she might not have to keep up the听defense for too much longer. Last year's brood听fledged in early August,听and this chick is听getting very close. If Rachel can keep the owl at bay, the听chick听might just be able to听leave this听nest鈥攁nd all听its drama鈥攆ar behind.听
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探花精选 is a nonprofit working to save birds and the听places they need. To support our conservation efforts, 听
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