Olive-sided Flycatcher

The Olive-sided is the least common of New Hampshire’s breeding flycatchers. It is a species of the northern forest, where it frequents bogs, beaver wetlands, clear cuts, and other open habitats with prominent perch trees. It is most often heard before it’s seen, and easily identified by its loud and distinctive “Quick, three beers!” song. This species is only on its New Hampshire nesting grounds for a couple of months, arriving in late May and often leaving in early August. If you find an Olive-sided south of the White Mountains in early June, it’s far more likely to be a late migrant than a nesting bird. 

Unfortunately, Olive-sided Flycatcher populations are in decline across their vast range, from Alaska to Newfoundland and south in the mountains to Baja California, Arizona, and (formerly) Tennessee. Here in eastern North America, the distribution has been retracting north for decades, and the species is now increasingly rare south of northern New York and New England. Surveys conducted in New Hampshire in 2014-16 revealed that the species had largely disappeared from formerly occupied areas south of the Lakes Region and was less common in the White Mountains. Only in the lowlands of Coos County did its distribution appear unchanged from the 1980s. This is one of the few cases of clear range retraction for any widespread New Hampshire breeding bird. 

But while the decline is obvious, the reasons for it are largely a mystery. Very little research has been done on this species in the East, but in the western United States it is often associated with edge and disturbed habitats, including forests damaged by fire. Yet the species continues to decline despite an abundance of forest management and increasing fire. In the east, the abundance of beaver wetlands would similarly seem to be beneficial to the species. In the absence of a smoking gun on the breeding range, conservationists have turned their attention to the mid-elevation forests of the northern Andes, where most Olive-sided Flycatchers spend the winter. Loss of habitat here to expanding agriculture has been identified as a probable threat to several other migrants that travel to this part of South America. It’s also possible that changes to insect populations on the breeding grounds are a problem, and more research is desperately needed.