Yellow-rumped Cacique

The yellow-rumped cacique is a slim, long-tailed songbird of the New World blackbird family that breeds across much of northern South America, from Panama and Trinidad south to Peru, Bolivia and central Brazil. Its plumage is mainly black, set off by a bright yellow rump, tail base, lower belly and wing epaulets, with blue eyes and a pale yellow, pointed bill. It lives in open woodland or cultivation with large trees and eats large insects, spiders, nectar and fruit. It breeds in colonies, with up to 100 bag-shaped nests hanging in one tree, usually a tree that also holds an active wasp nest.

About the yellow-rumped cacique

The yellow-rumped cacique is a slim black-and-yellow songbird in the New World family Icteridae, closely related to the red-rumped cacique. It lives in northern South America, from Panama and Trinidad south to Bolivia and central Brazil, and nests in noisy colonies of hanging woven nests at forest edges.

It is a slim, long-tailed bird with a sharply pointed bill. Most of the plumage is glossy black, broken by a bright yellow rump, a yellow base to the tail, a yellow lower belly and a yellow patch on each wing known as an epaulet. The yellow stays visible even when the bird is perched, which is one way to tell it from the closely related red-rumped cacique.

The eyes are a pale, striking blue, and the bill is pale yellow to greenish yellow. Males and females share the same pattern, but the female is a duller black and noticeably smaller. Males average about 28 cm (11 in) and 104 g (3.7 oz); females average about 23 cm (9.1 in) and 60 g (2.1 oz), so a male can weigh well over half again as much as a female.

Young birds look like females at first but have dark eyes and a brown base to the bill. Plumage and eye color change over the first few years: second-year birds already have a clean yellow bill and blue eyes, and full adult coloring arrives by the third year.

Cacicus cela was first described by Carl Linnaeus in 1758, who named it Parus cela and mistakenly gave its home as India. Three subspecies are recognized. The two western forms, found from the Panama Canal area to Colombia and from western Ecuador to northwest Peru, may turn out to be a separate species, the saffron-rumped cacique.

Behavior and diet

Yellow-rumped caciques are diurnal and highly social. They forage in tree canopies for large insects such as beetles, caterpillars, crickets, grasshoppers and katydids, and they also take orb-weaver spiders. Adults round out their diet with nectar and fruit, including figs and the fruit of the chupa-chupa tree. They will drop into the understory to feed, but their bright yellow markings make them easy for predators to spot there.

The male's song is a rich mix of fluting notes, cackles and wheezes, sometimes with mimicry of other sounds. A busy colony can be heard from a long way off. Song is central to colony life: each colony shares five to seven song dialects that differ from those of neighboring colonies, and the dialects shift through the breeding season. Members pick up the changes quickly, which lets a colony recognize outsiders.

Young birds learn songs in two phases. They memorize songs starting a few months after hatching and keep at it into their first breeding season, but they don't fully settle on a finished, "crystallized" song until their third year.

Colonies, wasps and breeding

The yellow-rumped cacique is a colonial breeder. A colony may hold anywhere from 2 to 250 nests, usually with 40 to 100 in use at one time, and all of them sit in one or two trees. A single tree can carry up to 100 nests. Each nest is a bag 30–45 cm (12–18 in) long, woven mostly from twigs and leaves, widening at the bottom and hung from the tip of a branch.

The tree usually also holds an active wasp nest, and that is no accident. The wasps help keep mammals away; one species, Stelopolybia fuscipennis, has been seen driving monkeys off. The birds still have to keep enough distance from the wasps to avoid being stung. Some colonies nest on islands, where water protects them from snakes, and where black caimans may eat or turn back snakes before they reach the nests. Colonies also mob other birds that come too close.

The mating system is polygynous: one male mates with several females. Males compete through size, aerial grappling, face-to-face "shouting" and counter-singing, matching one another's songs until one bird falls behind, and the heavier, more dominant males win access to more females. Females compete too, fighting and stealing nest material to claim the safest spots near the wasp nest.

Females do all of the nest building, incubation and feeding. The breeding season runs about eight months, from July to February. A clutch is two pale blue or white eggs with dark blotches, each weighing 5–6 g (about 0.2 oz). Incubation starts after the second egg is laid, and the eggs hatch in 13 to 14 days. Usually only one chick survives per nest. Nestlings are fed arthropods, mostly grasshoppers, and leave the nest after about 25 to 40 days. Males help only by guarding the nest and territory while the females forage. Both sexes reach breeding age at about two years.

Known predators of adults include hawks of the genus Accipiter and forest falcons of the genus Micrastur. Giant cowbirds raid the nests of yellow-rumped caciques and of russet-backed oropendolas, a common neighboring species.

Range and habitat

The species breeds across much of northern South America, from Panama, Venezuela and Trinidad south to Peru, Bolivia and central Brazil. East of the Andes it ranges throughout the Amazon Basin, and it is found in every northern South American country and across the upper half of Brazil. It is more common in the tropics than in cooler regions. Stray birds have been recorded as far north as the Mexican state of Nayarit.

This is an "edge" bird rather than a deep-forest one. It prefers forest borders next to open areas such as fields and lakes, open woodland, and farmland with large trees. Nests go high in the canopy, though the birds also use dense shrubs. Because of this preference, yellow-rumped caciques often live close to people, around ranches and even in towns, and recorded habitats include suburban and estuary edges.

Conservation status

The yellow-rumped cacique is listed as Least Concern on the IUCN Red List, most recently assessed in 2020. It is abundant across its range and is not considered threatened.

If anything, it has gained from human change to the landscape. Forest clearance and ranching have opened up the edge habitat it likes, and it readily nests near farms and towns. It eats large numbers of insects, including pest species, around those settlements. In Peruvian folklore, caciques and oropendolas are called paucar, and this species in particular is known as paucarcillo, "little paucar." A tale from Moyobamba says the bird was once a gossiping boy in black trousers and a yellow jacket, and its appearance is said to bring good news.