Ask Maine Audubon: Give These Attacking Blue Jays What They Want
A recurring question we receive at Maine Audubon comes from people who have woodpeckers “attacking” their homes. I have already written about this problem here; this is usually from young birds trying to find food. Fortunately, for the sake of the owner, there is no food (eg insects) living in their coating, and this also tends to be temporary. Another temporary home wrecker that Kay and Shep Shepardson wrote about this week is the blue jay. Although some of the solutions may seem similar, the reason for the jays’ home attack is entirely different.
First of all, it is surprisingly common to observe blue jays “attacking” a house, and in particular attacking the paint. Project FeederWatch is a Cornell Lab of Ornithology citizen science project that asks anyone who owns a bird feeder to report birds they see at their feeders during the winter and conducted a study of this evil jay behavior at the late 1990s. The root of this behavior is that jays seek out sources of calcium to supplement their diet, and many paints get their pigment from sources like limestone or chalk (calcium carbonate). The FeederWatch study asked volunteers to see which birds would take additional sources of calcium and remarkably nearly 40% of observers documented this in blue jays.
So how to solve this problem? First, let’s call it the “If you can feed them, join them” solution: since they’re apparently looking for a source of calcium, give them one! You can use crushed eggshells as an alternative to your paint. just be sure to sterilize them first by boiling them or heating them in a 250°F oven for 20 minutes.
The other solution, similar to the fight against destructive spikes, is deterrent. Try putting something between the jays and where they strip your paint. Since this behavior is usually short-lived, there’s no need to use something permanent or “pretty”. I’ve had success hanging pewter pie plates; they’re fairly cheap, easy to pierce and tie a string, are lightweight, blow in the wind, and reflective so they scatter light. Aluminum foil is another option, especially if the jay uses a larger area. You can hang sheets of aluminum foil with thumbtacks, or even try wrapping them around the target areas. I’ll note that the Shepardsons didn’t specify if their upholstery was painted, just that it was wood. I encourage anyone with similar issues, whether jays or woodpeckers, to be sure to address any pest issues before any bird issues.
DISTINCTION OF EAGLES
Has everyone heard of Steller’s sea eagle that was at Boothbay in January? I’m sure you did, but among that Russian wanderer and the many bald eagles that live on the Maine coast, there was also an immature golden eagle! Visiting birder Melissa Roach spotted the golden eagle soaring south of Factory Cove in Boothbay on Jan. 8, and I’m pretty sure this is the first time anyone has seen THREE species of eagles in one spot and at the same time, anywhere in the country! While nothing matches the rarity of Steller’s sea eagle, it should be noted that golden eagles are also very rare in Maine and should always be very carefully identified. Given the amount of questions that have been raised after the golden eagle sighting, I wanted to provide a quick introduction to eagle identification in Maine.
I want to start by acknowledging that golden eagles are probably one of the most commonly misidentified birds in Maine. It takes about five years for bald eagles to achieve their adult plumage, including that “bald” white head, and it’s especially in their first year of life that they can be very dark overall ( including the head). These all-brown eagles are often reported to us as goldens, probably with the same frequency that large coyotes are called wolves in Maine (which is a lot). A more diagnostic plumage feature is evident when you see the birds in flight: look for where the bird shows white in the wing. On our immature bald eagles, they will show white on the inner part of the wings, the smaller “coverts” (what we might colloquially call the bird’s “armpits”). The golden eagles we get in Maine are almost all immature birds, showing white at the base of their flight feathers (the inner primaries and secondaries), and their coverts are all dark.
Size is certainly the hardest thing for observers to reliably distinguish, and is actually not a useful terrain mark for distinguishing bald from golden eagles. Goldens reports usually say “it was HUGE!” Much larger than a bald eagle’, but golden eagles are only larger in mass, while bald eagles actually have a slightly longer wingspan. It was really interesting to get reports from all over the state when people were looking for Steller’s sea eagle, with most people saying “it must have been Steller’s because it was so big!”
There is an underestimated bias in our perspective when identifying birds, particularly when judging size, and it is best exemplified by the full moon and what is known as “the illusion from the moon”. I won’t go into the full explanation here, but you’ve probably observed the “moon illusion”. You see a huge full moon rise above the horizon, but a few hours later it looks like a full-sized moon again when higher in the sky. The moon obviously hasn’t changed in size (or indeed moved away), but how your mind perceives its size based on the objects around it is an optical illusion. This same effect also makes us bad at judging the size of birds flying over the horizon.
All of the birder biases you’ve probably heard about from eyewitnesses, and why their accounts of events can be so flawed, are also true of birders. I’m sure we get it right most of the time (or is that just confirmation bias?), but it’s good to know how wrong we can be. When in doubt, take a picture! The resolution of most modern smartphones is remarkable, and even very poor quality photos can show significant diagnostic field marks.
Do you have a nature question for Doug? Email questions to [email protected] and visit www.maineaudubon.org to learn more about backyard birding, native plants, and Maine wildlife and habitat programs and events. Doug leads free birding walks on Thursday mornings, 8-10 a.m., at Gilsland Farm Audubon Sanctuary in Falmouth.
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