Fauna of Venezuela

The white-bearded helmetcrest is only found in northwestern Venezuela

Some birds resident in Venezuela span a variety of habitats; others are restricted to areas with certain types of vegetation.[11] Birds which can live in any area of Venezuela, including its cities, include the bananaquit, black vulture, blue-gray tanager, great egret, and the tropical mockingbird, among others.[11] Most birds of Venezuela span various habitats, but a few are specialized to only one area, typically due to extreme location or dependence on a certain resource; species restricted in this way include the Carrizal seedeater, maroon-chested ground dove, point-tailed palmcreeper, Río Orinoco spinetail, white-bearded helmetcrest and the white-plumed antbird.[11] Venezuela has particularly bio-diverse habitats, allowing for different types of specialist birds.[11]

The Tinamidae of Venezuela are typically found in forests, living on the land and roosting in low-lying branches. Odontophoridae also live in the forest and on the ground; there is one native Venezuelan species of this family, and it spends more time in the open than the others. The Cracidae are typical of the forest but have more diverse habitats, including one species living in Venezuela that has adapted to urban environments; they also are more often found in trees than on the ground.[11]

The large water birds Anhimidae are found in watery areas of the country, but roost in trees more often than their smaller counterparts the Anatidae, a migratory family of water birds, do; these are also found in most areas of Venezuela where there is water. The even smaller Podicipedidae live exclusively in the water; only two species of these live in Venezuela: both are native and live in freshwater. One species of Diomedeidae can be found in Venezuela; they live almost exclusively around water at sea, visiting land to breed.[11]

Observed in 1955 by Gilliard, the nesting and breeding season for birds across the regions in the north of Venezuela begins in late April. Gilliard, with great assistance from the Phelps family, sampled the entire northern region from sea level to 5,000 feet.[12] Gilliard and Ramón Urbano determined that the birds begin nesting as the rainy season begins, a conclusion supported by other ornithologists working in the region. Gilliard then comments on the different natures of some species, particularly those whose habitats span a range of altitudes, to have indeterminate and/or cyclic breeding periods.[12] Thirty-two species were recorded on this expedition, many of which were breeding during late April and early May.[12]

In 1994, the diets of land birds in the northeastern regions of Venezuela were estimated by Canadian researchers.[13] They concluded that most of the species of birds examined were "generalist feeders", and so ate a variety of both plants and invertebrate animals; of the invertebrates, the most common prey for birds in the region were beetles, ants and insect larvae. The researchers do note that most of the hummingbirds differed by eating largely soft-bodied arthropods and having a low nectar intake; most of the species ate plenty fruit.[13] On the odd occasion, some small mammals were captured by birds; kingfishers also demonstrated eating fish.[13]

A study of small mammals within agricultural areas of Venezuela's Western Llanos, largely Portuguesa, showed ten rodent species and three marsupial species. Most of the different habitats across this area showed a large prevalence of the rodents Sigmodon alstoni and Zygodontomys brevicauda, which appear to dominate the region.[17] However, areas of subsistence agriculture showed much more diversity and greater equal weighting of the inhabitant species.[17] Some of the rodent species may be seen as pests because of their destruction of crops and for transferal of disease to humans in such rural areas of South America; both the most prevalent rodents are carriers of particularly endemic diseases.[17]

The Maracaibo Basin spans northwestern Venezuela. There are two species of mammals that are both endemic to and characteristic of this region, and to similar dry forests in Colombia and Venezuela; the Guajira mouse opossum and Hummelinck's vesper mouse.[18]