Rufous-rumped Antwren

How to find it

Look in the canopy of mature forest and check every mixed-species flock, since the antwren is usually found inside one. Tapanti is one of the better places to try, though the bird is still rare there. Birding the park's main road is the usual approach, and cloudy weather can bring plenty of bird activity. Watch for a small long-tailed bird flicking busily through foliage at branch tips. Expect quick views: one tour group saw two flit through a tree overhead and noted the patterned wings well but not the rump.

How to recognise it

This is a tiny, slim, long-tailed bird, about 10 to 12 cm long, and it looks a bit like a greenlet or a New World warbler. The bill is fairly long and narrow.

The male has a black crown, a pale gray face and breast, an olive back, two pale yellow wing bars and a pale yellow-green belly. The bright rufous rump is often hidden by the folded wings, so do not count on seeing it.

The female is duller. She lacks the black cap and has a brownish olive crown, and her wings look like her back rather than black with yellow bars.

For a beginner, the marks to watch for are the black cap, gray head, olive back, yellow wing bars and yellow belly, together with that long tail.

Behaviour and diet

It forages in the canopy or subcanopy of forest, sometimes hanging upside down. It travels alone or in pairs that join mixed flocks, and it is usually noticed, if at all, within mixed flocks of insect-eating birds.

It eats mainly insects, searching actively among foliage at branch tips. That constant movement, together with the long tail, helps separate it from other yellow-bellied antwrens. It usually moves in pairs, so when you find one, look for a second.

Where it lives

In Costa Rica it lives on the Caribbean slope, from southern Alajuela southward. It is recorded between about 700 and 1,200 m elevation. The northernmost population is on the eastern slope of the Talamanca range, shared with Panama. Across its range it is a bird of the canopy of mature forest, which is where its mixed flocks pass through.

When to see it

Breeding in Costa Rica seems to run from February through May, and little else is known about its nesting. Tour reports show sightings in February and in mid-May, which shows it can be found then but does not show a seasonal pattern.

Similar birds

The Chestnut-shouldered Antwren also has a rufous rump patch, but it lives only in lowlands and males show a chestnut shoulder patch. The two barely overlap in range. Since the rump is hard to see, rely on the black cap, gray head, olive back, yellow wing bars and yellow belly.

Names and lore in Costa Rica

Costa Rica uses Hormiguerito Lomirrufo. Colombia says Hormiguerito Culirrufo, Venezuela says Hormiguerito Rabadilla Rufa, and Peru says Hormiguerito de Lomo Rufo. Some sources also call it Tiluchí Lomirrufo.

Status and conservation

The AOCR list marks it R, it is considered rare in Costa Rica, and the IUCN rates it Least Concern worldwide, though the population is thought to be shrinking.

Photography tips

The rump is hard to see, so focus on the black cap, gray head, olive back, yellow wing bars and yellow belly. The bill is fairly long and narrow. It usually moves in pairs, so once you find one, stay with the flock and watch for the second.