A variegated flycatcher, normally in South America, certainly overshot its target when it showed up in Maine. Carline Jean/Sun Sentinel

In today’s column, we’ll continue our exploration of changes in the Maine bird fauna as we celebrate this bicentennial year of our state. Let’s start with some mega-rarities.

Intentional flights, faulty navigation skills and storms can all take birds to unexpected places. Here are some that have only once occurred in Maine in our 200-year history.

In November of 1979, a flycatcher with dense streaking appeared at Biddeford Pool. The bird was first identified as a sulphur-bellied flycatcher (now called streaked flycatcher), a non-migratory species found in southeastern Arizona and further south. Further analysis showed the bird was actually a South American bird, a variegated flycatcher. This species nests broadly across South America and the most southerly populations migrate north in the austral spring (October to November) to nest in equatorial areas. The one that showed up in Maine overshot by a lot.

Shorebirds are among the strongest migratory birds so finding out-of-place shorebirds is expected from time to time. How about these Maine records? A common ringed plover in Lubec, a European golden-plover in Scarborough, a bar-tailed godwit at Pine Point and a gray-tailed tattler flying past Matinicus Rock (all four Eurasian species) and a surfbird (a Pacific coast species) in Biddeford Pool. A great knot on Seal Island was certainly jaw-dropping for a species from northeastern Russia.

Roseate spoonbills occur commonly in the southern half of coastal Florida. One might expect Maine’s first to show up at a site like Scarborough Marsh. But no, our only record is from a small pond in Dover-Foxcroft.

Kirtland’s warbler is a rare species with a current population of about 2,300 pairs. They nest in jack pine forests in northern Michigan, Wisconsin and Ontario and winter in the Bahamas. What are the odds of finding one on the Kennebunk Plains in late May? Pretty slim, but it happened.

Eye-popping records of songbirds include a violet-green swallow on Mount Desert Island (a western species) and a fieldfare in Newcastle (a Eurasian species). A remarkable hummingbird record was the Mexican violet-ear on Mount Desert Island .

A crested caracara stands on a post during an exhibition at the Biopark “La Reserva” in Cota, Colombia. The crested caracara is a bird of prey restricted to central and southern South America, but one did show up in Maine. Fernando Vergara/Associated Press

Finally, birds of prey from distant places have appeared in Maine. A crested caracara (Florida is the closest source population) showed up in Kennebec County. Our most famous rarity has to be the great black hawk (a Central and South American species) that appeared briefly in the Biddeford area in August of 2018 and spent much of the fall and early winter in a park in Portland. Hundreds of birders, including many out-of-staters, came to Portland to add the species to their North American life list. Sadly, the hawk did not survive the winter.

These rare birds excite us and inspire awe. But let’s switch to our common birds and examine how their numbers have changed over Maine’s history.

We can start with the house finch, a regular feeder bird that was not found in Maine until the early 1970s. This species is common in the western half of the United States. These birds were sold illegally in the east as cage birds (called Hollywood finches). Hearing of a possible raid by the U.S. Fish and Wildlife Agents, a few finches were released in New York City in 1939. They readily established themselves and spread from Florida to the southern parts of eastern Canadian provinces. They have spread west, almost meeting the eastern range of the original population.

House finch numbers grew rapidly until 1994 when a lethal disease, avian conjunctivitis, caused numbers to plummet. House finch numbers rose again but have not reached their former abundance.

We have a suite of species that have increased substantially in the past 50 years or so. The explanations surely include climate change, population increases to our south forcing dispersal and changes in habitat. We’ll look at some of these species in the last column of this series.

Herb Wilson taught ornithology and other biology courses at Colby College. He welcomes reader comments and questions at whwilson@colby.edu