Over the last several weeks, migratory Fork-tailed Flycatchers (Tyrannus s. savana) have been migrating from their breeding grounds in southern and central South America to northern South America, where they will spend the austral winter.
In search of these migrants, José Ignacio Giraldo and Jonathan Candil Méndez visited several ranches (Villa Lorena, El Caribe, and El Brillante) near the town of Santa Rosalia in Vichada Department, eastern Colombia, from 11 to 20 April, 2016. They saw flocks of dozens of Fork-tailed Flycatcher migrants passing through, apparently feeding on fruit, and were able to band a few.
José Ignacio and Jonathan were also able to catch a few of the resident subspecies of Fork-tailed Flycatchers (T. s. monachus), which are lighter-colored than the migratory subspecies. Very little is known of the ecology and breeding behavior of this resident subspecies. Although José and Jonathan searched for nests they did not locate any, even though this is supposedly the time of year when this subspecies breeds.
Notably, on the morning of 15 April they also saw a large flock of about 500 Bobolinks (Dolichonyx oryzivorus) in grassland habitat. This is an increasingly threatened species that breeds in North America and overwinters in South America (south to Argentina). Given that spring is now underway in North America, this flock of Bobolinks were likely migrating back to their North American breeding grounds.
We thank the owners of the ranches visited for access to their property and hope to return again soon.