Northern Rough-winged Swallow

The Northern Rough-winged Swallow, Stelgidopteryx serripennis, presents itself as a modestly sized, migratory bird. Its plumage is a subtle brown above, contrasting with the white underparts. The species is named for the unique serrated edge feathers on its wing, a detail most apparent when one is fortunate enough to hold the bird in hand.

Identification Tips

Adults measure between 13–15 cm in length, with a wingspan of 27–30 cm and a weight of 10–18 g. They possess a small bill and a forked tail. The throat is white with a brownish-grey wash, leading to the white underparts. Males can be distinguished by their longer and broader undertail coverts and hooked barbs on the outer web of their outer primary wings, while females have shorter, straighter barbs. Juveniles are marked by their reddish-brown wing-bars.

Habitat

These swallows are often found in environments that provide open airspace for foraging, such as over water bodies and occasionally over land.

Distribution

The Northern Rough-winged Swallow graces a wide range, from southern Alaska and Canada to the southern United States, with wintering grounds extending from southern Florida to Panama. In Costa Rica, they have been observed at elevations as high as 2,500 m.

Behaviour

This species is known for its solitary nesting habits, although it may form loose groups. Post-breeding, large flocks are common, and they may roost together in marshes. Their flight is characterized by slow, deep wingbeats interspersed with glides.

Song & Calls

The call is a short, harsh "zeep" or a rough, low "bzzt," often doubled, and bears similarity to the call of the bank swallow.

Breeding

Nesting typically occurs in burrows within soil banks, with nests constructed from a variety of fibres and lined with grass, predominantly by the female. Breeding season varies by region, with a single clutch of four to eight glossy white eggs laid, and occasionally a second clutch if the first fails.

Similar Species

The Northern Rough-winged Swallow can be confused with the bank swallow but can be differentiated by its dusky throat and breast. It is also closely related to the southern rough-winged swallow, Stelgidopteryx ruficollis, which has a more contrasting rump.

Diet and Feeding

Primarily insectivorous, these swallows feed almost exclusively on flying insects, captured in flight with a foraging style that involves low and direct paths over water or land.

Conservation status

The IUCN classifies the Northern Rough-winged Swallow as Least Concern. Despite a declining population, the species is not at immediate risk due to its large population size and adaptability to human-altered environments.