Gray-headed Tanager: Ant Swarm Follower
On consecutive mornings in June in the Finca Cántaros forest I encountered Gray-headed Tanagers (Eucometis pencillata) accompanying army-ants as they moved through the leaf litter. Ever active and constantly twitching their tails and wings as they searched for insects escaping the ant swarm, they are a challenge to photograph, especially in the forest shadows. The birds stayed low, going from branch to branch within two to five feet above the forest floor and, when spotting a prey, landing among the ants to catch the grasshopper, beetle, fly and such. It seemed my efforts to get close to them hardly interrupted their determined feeding activities. I was also quite intent in my focus, and at one propitious instant forgot I was standing in an ant swarm. Of course a few stings on my ankles made me leap out of my crouched place, startling the birds, but not for long.
Richard Garrigues and Robert Dean’s Field Guide, The Birds of Costa Rica mentions that Gray-headed Tanagers follow not only army-ants, but also White-faced Capuchin Monkeys! The tanagers wait on low branches below active monkeys and sally out for insects as the monkeys disturb the foliage above.
Most other tanager species in our mid-elevation southern Pacific region are easily observed because they spend considerable time foraging for fruits and insects at forest edges, in sunlit trees and gardens, and they are avid consumers of papaya and bananas at our feeders. However the Gray-headed Tanager’s habits are completely different: they spend most of their time in dense forest understory either in pairs or mixed flocks. Interestingly, it is the only member of its genus Eucometis.
Although I don’t see the Gray-headed Tanager very often on our property, that’s probably because I am not spending enough time in the forest. It is a year-round resident and is considered common in the lowlands and foothills of the southern Pacific slope, from sea level to our elevation of 4000 ft (1200m). The Cornell Lab of Ornithology web page on Neotropical Birds describes the Gray-headed Tanager as having conical bills with large, rounded notches on the upper mandible. Research has shown this small bird (6½”) can live up to ten years.
Not considered endangered, the Gray-headed Tanager consists of seven subspecies that are found in forested habitats from southern Mexico to Northern Paraguay.
To attract more army-ants so we might see other interesting ant bird behavior in our forest, we would have to acquire significantly more forested land beyond our seven hectares of mixed gardens and forest. Sigh….not likely.
To hear a 12-second recording from Xeno-Canto of the high-pitched, squeaky song of the Gray-headed Tanager, click here and an audio player will open in a new tab/window. Then click the play ( ►) button. Close that tab/window to return to this post.
Additional reference: A Guide to the Birds of Costa Rica by F. Gary Stiles and Alexander F. Skutch.