Catching up with a boreal flycatcher

By Joan Collins

One of the Adirondacks’ most sought-after boreal species, by visiting birders, is also one of the most entertaining to observe.

With their loud “quick, three beers” song, the olive-sided flycatcher won’t elude your ear. Their habit of hunting insect prey from exposed perches of tall, dead “snags,” makes them easy to spot. No searching through the leaves to see this species!

The elegant-looking olive-sided flycatcher with its formal vest breeds in wet areas with dead standing trees where they can be found sallying—flying out and back—for insects, like the motion of a yo-yo. In the Adirondacks, their habitat can be found along the edges of bogs, along boggy/marshy areas by rivers, brooks, streams, lakes, and ponds, and in beaver-created wetlands. Although they are easy to hear and see, getting close to their wet habitat can often be a challenge.

With their mid-May return from wintering grounds in South America, you can observe family groups in the Adirondacks by the middle of summer. They continue to loudly sing and call (pip-pip-pip) into August. You can watch them sallying from exposed perches to snatch prey—primarily bees, wasps, flying ants, moths, grasshoppers and dragonflies. 

Once, while leading a group, we spotted a fledgling on a snag. Its parent flew in to feed it a dragonfly. However, like an unappreciative toddler, the fledgling kept turning its head away when the parent tried to push the dragonfly into its bill. The parent persisted (it looked like the bird was thinking, “I caught this, and you will eat it!”) and finally shoved that huge insect into the fledgling’s mouth. It was an entertaining battle.

In the U.S. and Canada, a staggering net population decline of nearly 3 billion various birds has occurred since 1970, representing a loss of 1 in 4. Several family groups are declining faster than others, including grassland birds, migratory shorebirds and aerial insectivores such as swallows, flycatchers, swifts and nightjars, that feed while in flight.

In New York, the olive-sided flycatcher showed a more than 50% decline in confirmed breeding blocks between the 1980-85 and 2000-05 Breeding Bird Atlases. The state considers it a species of greatest conservation need.

In Vermont, aerial insectivores showed the largest decline of any bird group in a 25-year study. The olive-sided flycatcher is an aerial insectivore completely dependent on flying insects to survive. Its population has declined 78% since 1970 according to Partners in Flight, which has listed this species, along with 83 others in North America, as most in need of conservation action. It is also included on the International Union for Conservation of Nature’s Red List of Threatened Species.

The olive-sided flycatcher population is declining across its breeding range, which spans Canada, the western U.S. and the northeastern U.S. with the Adirondacks representing the southeastern edge of this range. Interestingly, within its breeding range, there has been an increase in appropriate nesting habitat, including beaver-created wetlands in New York as the beaver population has rebounded after nearly being wiped out from trapping and deforestation in the 19th century.

 Reasons for the population decline can be complex, but scientists suspect that the more serious problems are tropical deforestation, changing forest conditions and climate change on the wintering grounds in South America (including steep declines in insect populations in the tropics). Climate change and decreasing insect populations are likely playing a similar role in the population declines in the Adirondacks and the rest of its breeding range.

Hopefully, we will continue to see the charismatic olive-sided flycatcher in the Adirondacks well into the future.