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Ask Maine Audubon: Digital photography allows for closer study of rare birds

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The ferruginous hawk seen in Auburn last week was a rare bird sighting that was on nobody’s radar. The open habitats of the grasslands and deserts of the west are ideal for the ferruginous hawk. Photo by Gary Jarvis

Summer is not when we typically think of rare birds showing up in Maine. This newspaper has given great coverage to many of the vagrant birds that have strayed to Maine over the years, but most of those are tied with migrations in the spring or fall, or sometimes after storms. Among the list of rarities, Maine has hosted a few raptors in recent years that have attracted large crowds, notably the Steller’s sea eagle over the winters of 2022 and 2023, and the great black hawk that frequented Deering Oaks Park in Portland in 2018. A western marsh harrier found on North Haven in August 2022 was another bird not on anyone’s radar, so while no one would have ever guessed, it feels like we shouldn’t have been surprised when a ferruginous hawk was found in Auburn last week – the first record for New England.

With the Steller’s sea eagle coming from eastern Siberia, the black hawk from central America, and the marsh harrier from Europe, perhaps we were due for a rare North American raptor, albeit one from the grasslands and deserts of the west, that rarely strays east of the Mississippi. These open habitats are ideal for ferruginous hawks, which would explain its attraction to the Auburn-Lewiston airport where it was found by local birders Christine Murray, Gary Jarvis, and Camden Martin.

One of the coolest trends with modern birding, which has really come thanks to advances in digital photography, is the ability to match photos of known individuals between locations. When a rare bird is seen in two different areas, historically we would have only been able to guess that it was one individual, or would have assumed they were two different birds. Our detection rate of rare birds must be incredibly low. After all, what are the odds of an out-of-range bird being seen by someone, that person knowing that it’s a rare bird, or even taking a photo, and then reaching out to a state bird records committee or local Audubon. It must be well below 1% of all the vagrants that occur.

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Now, with really good digital cameras becoming more prevalent, we often end up with hundreds of photos of a single rare bird, capturing all angles and many feather details. For example, there are 2,241 photos of the Steller’s sea eagle in the Macaulay Library database (tied to Cornell’s eBird records) from that one bird’s time in Maine. With these photos, we can start matching unique feather patterns to other nearby sightings and sometimes we get a match. The Steller’s sea eagle had unique markings on its wings that matched it to a long string of records across the country before getting here. Our great black hawk was matched with photos from Texas (officially the first time the species had been detected in the United States), four months before being found in Maine.

All this leads me to point out that the unique markings on groups of underwing coverts (the little feathers that give the wing shape) on the ferruginous hawk’s wings, seen in Auburn, match perfectly with one that was seen in southern Ontario, on the shore of Lake Erie in early May. Where has this bird been since then? Why is it here? We may never know.

I do want to acknowledge the identification challenges with these birds. After rare bird sightings hit the news or social media, we always receive a bunch of reports, almost always of similar-looking species. The ferruginous hawk is similar to our abundant red-tailed hawks, though larger (15-20%), and the Auburn individual is one of the light color morphs, so it shows a very pale head and almost entirely unmarked white chest and belly, unlike the darker red-tails. I encourage anyone who thinks they see a rare bird to get a photo and send it to naturalist@maineaudubon.org.

These are some fascinating examples of rare raptors that have shown up in Maine, all coming from vastly different places. That’s one of the fun aspects of this hobby. We are constantly learning new things from these birds. Advances in technology through photography allow us to get high quality images and social networks spread the word out to observers quickly. Following the path of a bird well outside its typical range leads us to wonder how it got here and why, and that’s where the fun comes in.

Have you got a nature or wildlife question of your own? It doesn’t have to be about birds! Email questions to ask@maineaudubon.org and visit www.maineaudubon.org to learn more about birding, native plants, and programs and events focusing on Maine wildlife and habitat. Doug and other naturalists lead free bird walks on Thursday mornings, 7 to 9 am, at Maine Audubon’s Gilsland Farm Audubon Sanctuary in Falmouth.

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