16 September 2024
Our largest swallow, the purple martin (Progne subis), has a really quick breeding interval in North America. In Pennsylvania they arrive in late April and fledge younger in mid July.
As quickly because the fledglings fly effectively, adults and younger go away the nesting space and spend their nights in a communal roost.
Flocking begins as quickly as nestlings fledge; birds of all ages assemble in roosts earlier than fall departure. This will likely signify nonbreeding exercise quite than a selected response to imminent migration, as a result of the species is very social and flocks in massive roosts all through the overwintering interval.
Because the breeding interval is earlier within the South, roosts within the Carolinas refill in July and comprise so many birds that their early morning departure will be seen on climate radar. This occurred final week in Wilmington, North Carolina.
Fb submit from NWS Wilmington, NC on 12 July 2024
The identical phenomenon occurs at our latitude in August, as proven on radar in Wilmington, Ohio at high.
Study extra about purple martin roost rings on this article from Wilmington Ohio: Roosting Birds Detected By NWS Doppler Radar and this one from Wilmington, North Carolina: Purple Martin Roost Rings on Doppler Radar.
