Red-bellied woodpeckers now breed across the southern half of the state but were still very rare prior to the 1990s. Ben McCanna/Staff Photographer

Spring migration is ramping up, and each evening we have tens of thousands of birds pass over Maine. On clear nights, a light south breeze can usher in a couple of million mostly songbirds migrating under the cover of night when there are few predators and the winds tend to be calmer.

This spring push will peak in May, but it has been going on for weeks already, and among our typical summer residents, some southern stars are getting a lot of attention. Many people have written in asking about these wayward birds, so we’ll cover what is bringing them up here.

The birds in question are migratory species whose range doesn’t usually reach Maine, and many barely make it into New England. These include, in the past week: at least seven blue grosbeaks – a cardinal-sized bird whose plumage (in males) is a deep blue color, also has a large bill, and is separated from indigo buntings by its chestnut shoulder patch; several summer tanagers – slightly larger than our regular scarlet tanager, males are an oversaturated orange-red color; a couple of prothonotary warblers; a yellow-throated warbler in Kennebunk; a swallow-tailed kite over Portland; and a painted bunting in Saco. It has been a very exciting spring for Maine’s birders and it is just getting started.

These birds are called “overshoots” because as they are migrating north; instead of stopping within their range, they overshoot and end up farther north than they would usually go. Why this happens isn’t always known, at least on the individual level, but there are generally a few factors at play. A strong tailwind is one of them. One of the first big influxes of these southern birds came over the weekend of April 13 and 14, after the passage of a low pressure system that gave us a few days of rain, and the resulting southern winds that came behind it.

Swallow-tailed kites will occasionally make their way to Maine. TNS

Some of these species could be prospecting – looking for potential new nesting sites. An obvious trend we are seeing with a warming climate is the spread of species northward, and while many of these will probably take decades before they could establish themselves in Maine, we have seen new species start to nest in Maine fairly recently. Red-bellied woodpeckers are perhaps one of the more well-known examples of a southern species expanding northward into Maine. It now breeds across the southern half of the state but was still very rare prior to the 1990s. Carolina wrens followed a similar pattern, and if we go back a little further in time, tufted titmice and Northern cardinals were a rare sighting, too.

Another good example of a Maine breeder we see overshoot within the state is the orchard oriole. Smaller and more brick colored than our Baltimore oriole, orchard orioles primarily only breed in York and Cumberland counties, with a couple of outliers sprinkled up to the Midcoast. Every spring, though, we see them push farther and farther north along the coast, with many seen at migratory hotspots like Monhegan Island. Although the fate of these birds is never really known, most are likely to turn around and head back within their range. We can tell this because they almost all leave by the end of the migration period, and only rarely do we get a jazzed-up male that stays around and sings his heart out for the summer, usually to no avail.

Another reason for all the overshoots could simply be that more people are looking. While this spring has been pretty exceptional with the number of these overshoots, I think they’ve also garnered more attention than I’ve ever seen, thanks to an increase in birders since the pandemic. There are definitely more people going out looking for these rarities when they occur, and having more eyes on the skies certainly increases our detections during events like these.

As an environmental educator, I think it’s great to see so many people getting excited about the birds we have around. I encourage you to keep tabs and at least bird vicariously through the Maine Birds Facebook group, check ‘rare bird alerts’ on eBird.org, and make sure you’ve got the (free) Merlin Bird ID app downloaded from Cornell to learn more about the birds that are around you this spring.

Have you got a nature question of your own? Email questions to ask@maineaudubon.org and visit 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 the Gilsland Farm Audubon Sanctuary in Falmouth.

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