Rufous-vented Ground-Cuckoo

How to find it

Watch for army ant swarms in primary forest, which is the best way to find this bird. Local guides at Heliconias have most often seen it by finding a swarm and staying with it until the cuckoos arrive, even if that takes two hours or more. Listen for bill clacks and for antbirds calling deep in the forest. One Costa Rican guide heard Ocellated and Bicolored Antbirds, then two bill clacks, and the ground-cuckoo stepped onto the trail and stayed for a long, close look. Expect patience: even at the more reliable spots it is seen only a couple of times a year at best.

How to recognise it

This is a large, long-tailed ground bird, about 45 to 51 cm long, with the tail making up about half of that.

Look for these marks:

A shaggy blue-black crest that it can raise.

Bright blue skin around the eye.

A rufous patch under the tail.

A brown chest and shiny purple on the back.

A heavy, curved bill, pale greenish or horn colored with a yellow tip.

Costa Rican birds belong to the subspecies salvini, a form with fainter scaling on the face and breast and pale buff to grayish underparts.

Behaviour and diet

It follows army ant swarms and catches the insects and other small animals that flee from the ants. It does not eat the ants themselves. It lives alone or in small groups, and it also tags along with peccaries and monkey troops to catch prey they flush.

At swarms it snaps its bill and raises and lowers its crest while chasing other birds away. Its calls seem to move other birds off the prey. The bill clack serves as an alarm and as contact between ground-cuckoos, and research says it resembles the sound peccaries make to warn each other of danger.

Where it lives

The species lives in mature, undisturbed humid evergreen forest. In Costa Rica it is found in dense, humid forests of the Caribbean slope. Its range covers wet forests on the volcanoes of northern Guanacaste, east to the Caribbean coast and most of Limón province.

Historically it ranged from the lowlands up to about 1,200 m on the Caribbean slope. It needs large areas of primary forest and does not survive in pasture, farmland or small forest patches in the Caribbean lowlands.

When to see it

One site says it is present year-round and that chances rise in the dry season, December to April, when army ant swarms are more active. The 2021 sightings at Bosque Eterno de los Niños were reported in February, March and November.

Similar birds

Bright blue facial skin is shared with many antbirds and other ant swarm followers, but the size, long tail and shaggy crest set the ground-cuckoo apart at a swarm. In Costa Rica a long, rufous-green tail low in the rainforest understory belongs to no other bird. It is the country's only Neomorphus ground-cuckoo, so the similar Scaled Ground-Cuckoo of South America is not a worry here.

Names and lore in Costa Rica

Costa Ricans call it Cuco Hormiguero, which means ant cuckoo. One Costa Rican bird art page says some people also call it Correcaminos, the Spanish word for roadrunner. Other Spanish names listed for the species include Váquiro Verde (green peccary) and Cuco Hormiguero Ventrirrufo.

Status and conservation

The official Costa Rican bird list gives it resident status (R) as Cuco Hormiguero, and the IUCN lists it as Vulnerable, rare and elusive in every country where it occurs.

Photography tips

Even after you find a ground-cuckoo at an ant swarm, it can be shy, and dense undergrowth makes it hard to see well. Many sightings are only brief glimpses of a bird slipping away, and birds feeding at a swarm can be wary and unpredictable. Guides also say these birds can seem fearless or curious, so stay still and let it come.