Yellow-rumped caciques typically do not live deep inside forests. They are considered an “edge” species, preferring to live along the forest borders near open areas such as fields and lakes. They typically nest in tree canopies, but also may be found in dense shrubbery. Because of their preference for forest borders, yellow-rumped caciques are frequently seen near areas of human activities. (Lowther, 1975; Munn, 1985; Robinson, 1986)
Yellow-rumped caciques are sexually dimorphic. Adult males range from 27 to 29.5 cm long and weigh approximately 100 g. Adult females typically reach 23 to 25 cm long and weight 60 to 80 g. Both sexes have similar colors, but females tend to be less colorful. Adults are mostly black but have a yellow spot on their wings and another bright yellow patch on their rump. They have pale blue eyes and a greenish yellow bill. When perched, the bright yellow colors can still be seen. This distinguishes yellow-rumped caciques from closely related red-rumped caciques (Cacicus haemorrhous). (Haverschmidt, 1948; Munn, 1985; Ridgely and Tudor, 1989; Robinson, 1986; Webster, 1992)
First year yellow-rumped caciques have brown patches on the base of the bill and dark purple eyes. In second year birds, the bill is clear yellow and they have blue eyes. Males have olive edges on the belly feathers and females have traces of purple in their eyes. By third year they will express adult coloration. (Haverschmidt, 1948; Munn, 1985; Ridgely and Tudor, 1989; Robinson, 1986; Webster, 1992)
Yellow-rumped caciques are polygynous, meaning that one male mates with many females. They are a colonial species, with group nests typically occupying one to two trees. Access to females depends upon dominance, which has been shown to correlate with weight. Larger size means greater numbers of females. Males compete with one another through their size and communication with aerial grappling and face to face “shouting”. In addition, males counter-sing to one another. The individual who cannot keep up with crystallized songs is defeated. In all male bouts, there is a distinct winner and loser.
Females also compete with one another within a colony. As with males, size plays in important role in female dominance. Female yellow-rumped caciques fight to obtain prime nesting spot to ensure their eggs will be safe. Nest materials and spots have been stolen from by neighbors and aerial grappling and “shouting” also occurs. However, unlike males, not all female bouts have a distinct winner or loser. (Robinson, 1986; Trainer, 1987; Webster, 1992)
The breeding season for yellow-rumped caciques lasts eight months, from July to February. Males mate with many females, but are limited by their ability to obtain and protect the females. After mating, males show no parental investment in the offspring except in aiding females in protecting the nest. While females are foraging or gathering materials, males assume duties for nest and territory protection. Re-nesting occurs at least once during the breeding season.
Females lay two eggs, each weighing 5 to 6 g. However, most of the time, only one egg survives. Eggs hatch about 15 days later and a single 2 to 3 g bird emerges. Mother birds feed her young arthropods. After about 25 days, young birds are able to fly on their own. Offspring mature in about two years, after having memorized most of the songs they will need in communication. (Robinson, 1986; Trainer, 1987; Webster, 1992)
Other than mating with females and protecting their territories, males play no part in parental care. Females are responsible for all other reproductive activities and offspring care. Females build the nests, incubate the eggs, and feed the young. Female mass fluctuates between 60 and 80 g throughout the process. The nests are typically built high in the canopy and hang from branches. Nests are built largely with twigs and leaves. Nestlings fledge when their weight reaches approximately 50 to 88 g, at about 25 days after hatching. Once young are capable of flying, mothers slowly gain their weight back which was lost while feeding young. (Robinson, 1986; Trainer, 1987; Webster, 1992)
There is no information on lifespan in the literature.
Yellow-rumped caciques are social birds. They nest on the outer edges of forests and sometimes in towns. Colony size can range from 2 to 250 nests. Usually 40 to 100 nests will be active at any one time. Yellow-rumped caciques are polygynous and males are territorial. The size of the male will determine the number of females with which he mates. Male dominance is measured by size and counter-singing. Competing males use songs to establish dominance. They match each other’s songs until one loses. Songs are very important because they are specific to individual colonies. Males use songs for attracting females and defending territories. (Robinson, 1986; Trainer, 1987; Webster, 1992)
Home range size is not reported. Colonies inhabit 1 to 2 trees.
Songs are acquired through two phases: memorization and crystallization. Memorization begins within a few months of hatching and continues into the first breeding season. Yellow-rumped caciques don’t fully crystallize their songs until their third year. Vocal signals are used to attract mates, defend territories, and advertise status. Colonies share 5 to 7 song dialects that differ from other colonies and are changed throughout the breeding season. Members are able to adopt these changes quickly and allow the colony to distinguish outsiders. Songs have social significances and males counter-sing one another to establish dominance. (Trainer and Parsons, 2002; Trainer, 1987)
Yellow-rumped caciques are insectivorous, feeding their young arthropods, mainly grasshoppers, crickets, and katydids (Orthoptera), but also orb-weaver spiders (Araneidae). Adults are not only insectivorous, but also fulfill their protein demands by eating fruits and nectar. Fruits of chupa-chupa (Quararubea cordata) trees are a favorite, along with figs (Ficus trigona). They also hunt in tree canopies for caterpillers and other invertebrates. (Robinson, 1986; Trainer and Parsons, 2002; Trainer, 1987)
Yellow-rumped caciques are vulnerable to predators while searching for food in the understory. Their bright yellow color makes them highly visible. Birds in the genus Accipiter (goshawks or sparrowhawks) and Micrastur (forest falcons) are known predators. Yellow-rumped caciques are also subject to many nest predators. However, they nest in areas that are well-protected from most mammals, snakes, and other birds. Wasp-nest colonies in close proximity provide protection from mammals, however, yellow-rumped caciques must ensure enough space between themselves and these wasps to avoid attack. Stelopolybia fuscipennis is a species of wasp that has been seen to drive away monkeys. Yellow-rumped caciques also sometimes live in island environments, which protect them from snakes. Caimans, such as the black caiman (Melanosuchus niger), often eat or deter snakes before they reach nests. In driving away other bird species, colony size is important. Other birds are "mobbed" by the colony when they posed a threat to nests. (Munn, 1985; Robinson, 1985; Robinson, 1986)
Giant cowbirds (Scaphidura oryzivor) have been noted as nest predators. They attack both yellow-rumped cacique nests and a common neighboring species: russet-backed oropendolas (Psarcolius angustifrons). Female giant cowbirds are more prone to visit the nests of oropendolas than caciques, but it has been suggested that the two neighboring birds have a mutualistic relationship. Cowbirds visiting unprotected oropendola nests may be driven away by male yellow-rumped caciques. (Canaday, 1996; Robinson, 1988)
Where yellow-rumped caciques nest on islands, their nests may be protected from terrestrial predators, such as snakes, through predation in by black caimans (Melanosuchus niger). Stelopolybia fuscipennis is a species of wasp that has been seen to drive away monkeys in yellow-cacique nest colonies. (Munn, 1985; Robinson, 1985; Robinson, 1986)
Yellow-rumped caciques do not appear to provide direct economic benefit to humans. However, loss of this bird is likely to contribute to human problems. Yellow-rumped caciques often live on the edges of forests and nearby towns. They are insectivorous and feed on a large number of pest insects. Along with this, many people enjoy listening to their songs. (Canaday, 1996; Trainer and Parsons, 2002)
There are no known adverse effects of (Canaday, 1996)on humans.
Mark Lubeskie (author), Radford University, Christine Small (editor), Radford University, Tanya Dewey (editor), University of Michigan-Ann Arbor.
living in the southern part of the New World. In other words, Central and South America.
uses sound to communicate
having coloration that serves a protective function for the animal, usually used to refer to animals with colors that warn predators of their toxicity. For example: animals with bright red or yellow coloration are often toxic or distasteful.
Referring to an animal that lives in trees; tree-climbing.
having body symmetry such that the animal can be divided in one plane into two mirror-image halves. Animals with bilateral symmetry have dorsal and ventral sides, as well as anterior and posterior ends. Synapomorphy of the Bilateria.
uses smells or other chemicals to communicate
used loosely to describe any group of organisms living together or in close proximity to each other - for example nesting shorebirds that live in large colonies. More specifically refers to a group of organisms in which members act as specialized subunits (a continuous, modular society) - as in clonal organisms.
ranking system or pecking order among members of a long-term social group, where dominance status affects access to resources or mates
animals that use metabolically generated heat to regulate body temperature independently of ambient temperature. Endothermy is a synapomorphy of the Mammalia, although it may have arisen in a (now extinct) synapsid ancestor; the fossil record does not distinguish these possibilities. Convergent in birds.
an area where a freshwater river meets the ocean and tidal influences result in fluctuations in salinity.
parental care is carried out by females
forest biomes are dominated by trees, otherwise forest biomes can vary widely in amount of precipitation and seasonality.
offspring are produced in more than one group (litters, clutches, etc.) and across multiple seasons (or other periods hospitable to reproduction). Iteroparous animals must, by definition, survive over multiple seasons (or periodic condition changes).
imitates a communication signal or appearance of another kind of organism
having the capacity to move from one place to another.
the area in which the animal is naturally found, the region in which it is endemic.
an animal that mainly eats all kinds of things, including plants and animals
reproduction in which eggs are released by the female; development of offspring occurs outside the mother's body.
having more than one female as a mate at one time
rainforests, both temperate and tropical, are dominated by trees often forming a closed canopy with little light reaching the ground. Epiphytes and climbing plants are also abundant. Precipitation is typically not limiting, but may be somewhat seasonal.
scrub forests develop in areas that experience dry seasons.
breeding is confined to a particular season
reproduction that includes combining the genetic contribution of two individuals, a male and a female
living in residential areas on the outskirts of large cities or towns.
uses touch to communicate
that region of the Earth between 23.5 degrees North and 60 degrees North (between the Tropic of Cancer and the Arctic Circle) and between 23.5 degrees South and 60 degrees South (between the Tropic of Capricorn and the Antarctic Circle).
Living on the ground.
defends an area within the home range, occupied by a single animals or group of animals of the same species and held through overt defense, display, or advertisement
the region of the earth that surrounds the equator, from 23.5 degrees north to 23.5 degrees south.
uses sight to communicate
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