Hog Island’s Osprey Pair Lose Chick to Nighttime Owl Raid

UPDATE: July 13, 2017, 9:45 a.m.: The Hog Island Osprey nest suffered another owl attack last night. Rachel attempted to fight the owl off but was unsuccessful, and another chick was taken. Rachel and one chick remain together safely on the nest at this time.

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Alas, another year, another nest predation for Rachel and Steve.

For the third year in a row now, Hog Island’s beloved Osprey couple has lost at least one chick from the exact same nest. For the past two, daytime raids by Bald Eagles have been to blame. But this year, a Great Horned Owl attacked in the midst of darkness. 

As the above clip from our Audubon and explore.org cam shows, the large owl stealthily snuck in a little after 1 a.m., plucking one of the slumbering chicks from the nest. In response, Rachel swoops from her perch to defend the nest while sounding her warning calls—but to no avail. 

Although Great Horned Owls are common on the Maine mainland, they are less so on Hog Island, making such predation behavior rare. “This was very surprising, actually, because we’ve never had an owl attack on Hog Island before,” says Steve Kress, vice president of conservation and director of Audubon’s seabird restoration program. “We don’t hear our Great Horned Owls hooting out here often. In fact, I haven’t heard any hooting this year. And we don’t know of any active nests.” 

Oddly enough, this wasn’t the first Great Horned attack on an Osprey nest caught on video this year. Earlier this month, an Osprey cam in Ontario, Canada, caught a Great Horned attacking a nest at night as well. Only in this one the owl decided to hang around and feast on the chick right in the nest. Kress says that the Ontario nest was a much easier target because those chicks were only left with one parent for protection after the female died. Males don’t tend to guard the nest at night, he notes. 

While these sorts of attacks aren’t typically caught on film, Great Horned Owl predation on other raptor nests are fairly common. In fact, according to Kress, they’re even one of the reasons the Peregrine Fund moved its falcon release sites from the countryside into canyons and even more urban areas where Great Horned Owls are less of a threat. “The owls just cleaned out their chicks,” Kress says. 

As for whether Rachel and Steve will take this third strike as a sign that it’s time to move, Kress says that what seems like a bad string of luck is really just nature, and in reality, raising any chicks to adulthood should be considered a success. “I think what we’re seeing is a typical kind of scene, where some chicks fledge, and some chicks are predated. I don't think they’re gonna move,” he says. “If they fledge any chicks, they’re going to keep coming back.” 

To add to to the drama of last night’s attack, all three chicks were supposed to be banded this morning by a crew from the Biodiversity Research Institute. Despite the surprise, the team proceeded with its plan and successfully banded the two survivors. 

Such attacks can be disturbing for people who follow cam nests closely, but Kress reminds that they’re a good opportunity for learning. “What we’re seeing here as always with these cams is a window to the real challenges of living in nature, where you’re constantly on guard, and the parents are making these decisions about whether to risk their own well being for the chicks,” he says.

There’s no way of knowing whether the owl will return for the other two chicks, but Kress says he’s interested to see if Rachel stays closer to the nest the next few nights. Last year, the Bald Eagle didn’t return after taking one chick, so the rest of the family might still be safe. But nothing is ever a given with nature. 

“When you think about all of those young birds just sitting in that nest—what a meal, what an opportunity to be fed on by a predator,” Kress says. “The nest is sort of like a bull’s-eye.” 

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