Bird identification is challenging, and never more than it is right now. August is the height of misidentification season.
In many species, young birds don’t resemble their parents. Their streaky, less colorful markings are intentional. Young birds are more vulnerable to predation and need all the camouflage they can get.
Chipping sparrows are a perfect example. Adults have plain white breasts and a rusty cap. Youngsters have streaky breasts and a dull brown cap. As ground feeders, chipping sparrows face danger from high and low. Because of that, families stay together longer in summer, while parents watch over their inexperienced offspring.
Chipping sparrow families are particularly easy to see, since they are comfortable in suburban neighborhoods. Unlike treetop fledglings that hide among the leaves, chipping sparrow families forage on the lawn in plain sight.
Camouflage wouldn’t help larger birds. Predators could spot a juvenile crow no matter what color it was. Hence, youngsters look like their parents. You will find crow families roaming neighborhoods now. They’ll join other crows in bigger flocks later in autumn, but for now, you should be seeing them in groups of five or so.
Observe a crow family closely, and you can figure which two are the parents. Crow fledglings have new, shiny feathers. Their overworked parents have dull, worn feathers, and may be missing a few.
Birds that take several years to mature will often sport annual plumage changes. Gulls and many raptors, including eagles, are notorious for this feature.
No one knows for certain why there is age-related variation in the plumage of some birds, but it’s the subject of much speculation. There are probably multiple reasons.
My favorite theory is that younger birds are color-coded so they can all tell age at a glance.
Immature birds avoid conflict with older birds, which are reluctant to beat up younger birds. Now if only I can find a beach full of eagles feasting on a dead seal to watch how those interactions play out.
Regardless, age-related plumage variation is a trait found in both bald and golden eagles, and that can cause identification problems at this time of year.
First-year bald eagles are mistaken for adult golden eagles. They are both dark, and the juveniles look larger than adult bald eagles. Indeed, young eagles are a bit bigger than their parents. They’ve just spent two months gorging on free food with no exercise.
Additionally, all female eagles are larger than the males. This sexual dimorphism is common in raptors.
It’s no wonder immature bald eagles are mistaken for golden eagles. They are the same size, except when they’re not. Their plumages are different, except when they’re not.
A few identification clues can help. Golden eagles have smaller heads and beaks, and slightly longer tails. This gives them a more streamlined appearance when flying. Bald eagles soar with their wings straight out. Goldens soar with wings in a slight V-shaped dihedral, like turkey vultures.
Nowadays, eagles are showing up on trail cams, opportunistically feeding on bait. Identification of a grounded eagle is challenging. But adult golden eagles have dark bills and eyes. Their legs are feathered all the way through the ankle. The eyes of a bald eagle get yellow as they age, and their feet are yellow and featherless.
Trail cam photos greatly aid in eagle identification. In January, Maine’s Department of Inland Fisheries & Wildlife launched the Maine Golden Eagle Study. Golden eagles are not known to nest in Maine. A pair formerly nested west of Baxter State Park, but their last breeding record was 27 years ago.
Over the last decade, golden eagles have been photo-verified at 44 sites across 35 townships. Some sightings were in areas where they had not been seen before, leading to suspicions that golden eagles may be nesting here again.
The department is working with volunteers to set up cameras and bait near most of those recent sightings. So far this summer, none have turned up.
Trail cam photos from baited sites are particularly valuable, but detailed observations reported to Maine eBird or Facebook Maine Birds also contribute to the project.
If you see something, say something.
Why study potential golden eagle nesting in Maine? We know they nest in Atlantic Canada. They fly through Maine. They could have nested in Maine any time since the last Ice Age. But mostly they haven’t.
If something has changed in Maine’s environment that now favors them, wildlife biologists would like to know.
