The Cocos tyrannulet, also known as the Cocos flycatcher, is a vulnerable species of bird in subfamily Elaeniinae of family Tyrannidae, the tyrant flycatchers. It is endemic to Cocos Island off Costa Rica.
Region
Eastern Tropical Pacific (Cocos Island)
Typical Environment
Restricted to the forested habitats of Cocos Island, including humid evergreen forest, secondary growth, and edges. It frequents streamside thickets, clearings, and coastal scrub near the ranger station. The species forages from the understory to mid-canopy but also uses open gaps to sally for prey. Despite its small range, it is adaptable to a variety of wooded microhabitats on the island.
Altitude Range
Sea level to 575 m
Climate Zone
Tropical
Ease of Keeping
Beginner friendly: 1/5
Also called the Cocos flycatcher, this tiny tyrant flycatcher is found only on remote Cocos Island, Costa Rica. It is listed as Vulnerable due to its very small range and susceptibility to invasive predators and habitat changes. It often forages close to people around the island’s station clearings, making it one of the most frequently seen landbirds there.
Illustration by Charles Haskins Townsend
Temperament
active but unobtrusive
Flight Pattern
short rapid wingbeats with brief sallies
Social Behavior
Usually seen singly or in pairs, maintaining small territories. Pairs likely remain together through the breeding season and defend nest areas. The nest is a small cup placed in shrubs or low trees, and both parents participate in care. Outside breeding, it can join loose mixed-species foraging groups.
Migratory Pattern
Resident
Song Description
A thin, high-pitched series of tsee and tseet notes, often delivered in short sequences from a low perch. Calls include sharp chips and soft trills used during foraging and pair contact.
Plumage
Small, plain tyrannulet with olive-brown upperparts and paler grayish face and throat; underparts are whitish to pale yellowish with an olive wash on the flanks. Shows two narrow pale wingbars and faint streaking on folded wings. The plumage is soft-toned and lacks bold contrasts.
Diet
Primarily small flying and perched insects such as flies, beetles, moths, and ants; it also takes spiders. It captures prey by short sallies from exposed perches and by gleaning from leaves and twigs. Occasional hovering is used to pick insects from foliage at forest edges. It rarely, if ever, takes fruit.
Preferred Environment
Forages along forest edges, stream margins, and light gaps where insects are abundant. Uses the understory and mid-story around clearings and along trails, often near the ranger station buildings.
