Conotos de Caracas | Monitoreo de aves urbanas

Description

The oropendolas are part of the family Icteridae. In Venezuela, only one of four species is found in almost the entire country: the Crested Oropendola (Psarocolius decumanus). It is a medium-sized bird (37-46 cm) with predominantly black plumage; its tail is yellow and the rump is chestnut brown. They have blue eyes and have a strong creamy white beak [5].

Gloria Mariño

This species is associated with forest edges that go from Panama to the north of Argentina. In Venezuela it is usually seen below 1900 m asl. The male has striking song, with an electro-acoustic sound, and is often accompanied by body movements. During courtship, the male leans forward, while singing, lowers his neck and keeps his tail up while beating his wings quickly [4,5,6].

Habits

Irina Formoso

These birds nest throughout the dry season on tall solitary trees, establishing colonies from 2 to 30 bag shaped nests. Each nest colony consists of a dominant male that mates with most of the females, and might include subordinate males. Crested Oropendolas are omnivorous birds and usually feed on insects, fruits, and nectar. Moreover, outside the breeding season, they usually move considerably and do not frequent the nests, which can fall during periods of intense rain [6].

In the following dry season, the oropendolas re-build their nests on the same tree, so they may be susceptible to the urban cut downs of certain tree species. The populations of these birds are potentially growing in Caracas, as seems to happen with the macaws that inhabit our city. Thus, with this study we seek to explain the factors that affect their demographic processes. In addition to their songs, behavior, social organization, and fascinating interactions, we have discovered several aspects of their biology thanks to the reports made on this website.

Unknown features

Thanks to your records we have known a little more about their interactions with other species. Oropendolas feed on various fruit trees and may disperse their seeds or compete with other frugivores. Also, in P.N. Henri Pittier the might be the prey of several species of raptors [9], some also present in Caracas, however, research is still needed.

It has been shown that Crested Oropendolas are pollinators of the Erythrina dominguezii tree in Brazil [7]. On the other hand, in Trinidad and Tobago researchers have proposed that Erythrina poeppigiana (Bucare) is pollinated mostly by passerines [3]. A favorable interaction between Bucares and these birds might exist, as our data suggest that most of the colonies in the city are built on these trees.

Likewise, knowing more about its reproductive season could tell us something about the annual climatic conditions of Caracas, since its reproduction and the construction of nests is associated with the availability of fibers and leaves during the dry season.

Enma Pescador

Additionally, there has been more sightings in Caracas than in other cities, such as Valencia (Carabobo) [1,2] and Palmas (Tocantins, Brazil) [10]. Taking a conservative approach, we estimated that more than 500 oropendolas are present in the city (at least 10 per colony, see Results). This population may be even larger, which encourages us to keep monitoring.

We are looking forward to keep working with you in this exciting endeavor!