Perception Channels: visual ; tactile ; acoustic ; chemical
Oropendolas are not endangered, therefore, they have no special status. However, the rainforests in which they live have been diminishing. Trees are cut down every day because of human development. It is fortunate that they adapt well to open country where scattered trees still remain to provide food and homes (Skutch 1996; Jaramillo and Burke 1999).
US Federal List: no special status
CITES: no special status
IUCN Red List of Threatened Species: least concern
They do not have any negative impacts on humans. Although confident in their own colonies, they tend to shy away in the presence of humans (Skutch 1996).
The bright yellow and chestnut brown feathers are used in the indigenous cultures of the Amazon rainforests as ornamentation. While they are worn for ceremonial occasions, they do not carry religious significance (American Museum of Natural History, 2000).
Psarocolius montezuma are also popular among bird watchers. They are great for sighting because of their colorful appearance and loud calls (Skutch 1996).
Montezuma Oropendolas are primarily fruit eaters. They have also been known to eat flowers from the surface of open grasslands, larger insects, and grass clumps of organic material. Females forage for food away from the colony in groups while males tend to search alone. They will eat throughout the day, but end their searches before dark (Orians 1985; Kraucunas 1996).
Psarocolius montezuma are found in southern Mexico to central Panama. Because the land is high and broad on the Pacific coast, they are restricted to the Caribbean side in Guatemala and southern Costa Rica. In northern Costa Rica, they are found on the Pacific slope for the same reason (Skutch 1996).
Biogeographic Regions: neotropical (Native )
Montezuma Oropendolas live in the rainforest regions near water and clearings, but not too deep in the forest. These birds can be found close to banana plantations and bamboo thickets. Tall, wide dicotyledonous trees are usually chosen, but they have been seen in a variety of trees if there is an absence of dicotyledonous trees (Skutch 1996; Jaramillo and Burke 1999).
Terrestrial Biomes: savanna or grassland ; rainforest
A large bird compared to other oropendolas, Psarocolius montezuma are very visible because of their bright colors. Males and females are mostly deep chestnut in color, except for shades of yellow on their outer tail feathers and a black head complete with a pale, blue patch of skin and pink wattle. Their sharp bills are black and orange, and in males, the orange extends over their forehead. Males also have extra skin on either side of their chin and are considereably larger than females, which accounts for the wide ranges of mass. An adult male can grow to 51 cm in length, while females are 38cm in length on average. Juveniles are similar to adults except the colors are duller and they are smaller in size (Skutch 1996; Jaramillo and Burke 1999).
Range mass: 230 to 520 g.
Other Physical Features: endothermic ; bilateral symmetry
Mating season is from January to May. Females, alone, incubate around 1-2 eggs at a time. After incubation, which can last around 15 days, the eggs hatch. Fledging occurs 15 days after hatching. A juvenile reaches sexual maturity in less than 1 month, but will not mate until the following year. The mortality rate is high in oropendolas because depredation occurs often by toucans, snakes, monkeys, and botfly larvae. Females will mate up to three times during the season, but less than one half percent of the chicks live past hatching (Kraucunas 1996; Jaramillo and Burke 1999).
Key Reproductive Features: iteroparous ; gonochoric/gonochoristic/dioecious (sexes separate); sexual ; oviparous
The Montezuma Oropendola (Psarocolius montezuma, sometimes known as Gymnostinops montezuma) is the largest member of the blackbird family (Icteridae). The sexes are similar in appearance, but males are considerably larger. Males average 47.5 cm long and 521 g (but some may exceed 560 g), females 39.2 cm and 246 g. The loud male song begins with low-pitched gurgles, then increases in pitch and volume, with complex harmonics, finally ending in a long note (listen to recordings under Media tab).
Montezuma Oropendolas are distributed along the Atlantic slope of central and southern Mexico and along the Caribbean slope from Belize south to southern Panama. They occur up to around 1600 m and are associated with humid tropical forest, often in clearings and edges (especially when breeding), as well as riparian forest along rivers and channels, second-growth forest, shady pastures, and plantations (banana, cacao, etc.).
The diet of Montezuma Oropendolas includes insects and other arthropods as well as small vertebrates such as frogs. Fruits are an important component of the diet, along with nectar from large flowers. Feeding is mainly high in trees, rarely lower down or on the ground. Because of the difference in size, males and females may tend to forage in different parts of a tree. Outside the breeding season, Montezuma Oropendolas often form mixed-species foraging flocks with other icterids and jays.
Montezuma Oropendolas are polygynous colonial breeders, with several to well over a hundred nests per colony constructed in one to several trees. Males in the colony form a linear dominance hierarchy, with the one or two highest ranking males siring most of the offspring in the colony. The nest, which is constructed by the female over 13 to 18 days largely from coarse plant fibers, is a purse 60 to 180 cm long, open at the top, and suspended from a branch tip. Nests are typically located over a river, channel, or road and sometimes even near buildings if the birds are unmolested. The two eggs are incubated by the female for 17 to 18 days. Nestlings are fed by the female and remain in the nest for around 35 days. Nests are often parasitized by the brood parasitic Giant Cowbird (Molothrus oryzivorus), although the host usually removes the cowbird's eggs. Males may attack nest predators and brood parasites. Reports from Costa Rica indicate that the second of the two hatchlings in a Montezuma Oropendola clutch typically survives for just a few days.
Other than some possible altitudinal movements in Costa Rica and Panama, these birds are essentially sedentary. Montezuma Oropendolas are locally common to uncommon and are found in many national parks and other protected areas. They tolerate (and may even benefit from) moderate deforestation.
(Fraga 2011 and references therein)
The Montezuma oropendola (Psarocolius montezuma) is a New World tropical icterid bird. It is a resident breeder in the Caribbean coastal lowlands from southeastern Mexico to central Panama, but is absent from El Salvador and southern Guatemala. It also occurs on the Pacific slope of Nicaragua and Honduras and northwestern and southwestern Costa Rica. It is among the oropendola species sometimes separated in the genus Gymnostinops. The English and scientific names of this species commemorate the Aztec emperor Moctezuma II.
Adult males are mainly chestnut with a blackish head and rump, and a tail which is bright yellow apart from two dark central feathers. There is a bare blue cheek patch and a pink wattle, the iris is brown, and the long bill is black at the base with a red tip. Females are similar, but smaller than males with a smaller wattle. Young birds are duller than adults and have a paler and less demarcated bill. No subspecies are currently recognized.
The sexes are very different in size; the male is 50 cm (20 in) long and weighs 520 g (18 oz); the smaller female is 38 cm (15 in) long and weighs 230 g (8.1 oz). In total body mass, the males are 100% bigger than the females, which is a 2:1 body-to-mass ratio and makes the Montezuma oropendola one of the most sexually-dimorphic birds in the world. Webster et al. says that the size difference in males and females is probably directly related to differences in foraging habits. The females often forage on thin branches, eating insects out of curled up leaves, while the males often perch on thick branches and forage in epiphytes and bromeliads.[2]
Webster et al. also found that sexual dimorphism was more obvious in length of the wing and body mass. Male size and body mass is associated with sexual fitness and dominance. Webster et al. observed that males defend sexually-receptive females, suggesting that Montezuma oropendolas have a female-defence mating system. While the females nest, the males fight and fend off one another, and the males were ranked depending on the outcome of each fight. The alpha male eventually pushes out all other males until he is the only one left. When the alpha males leave the others come back and defend females until he returns. This type of mating system is similar to that of polygynous mammals, not birds.[3]
The "unforgettable"[4] song of the male Montezuma oropendola is given during the bowing display, and consists of a conversational bubbling followed by loud gurgles, tic-tic-glik-glak-GLUUuuuuu. Both sexes have loud cack and crrrk calls. In a recent study by on male Montezuma oropendolas, researchers found that, when at breeding sites, males often changed the lowest peak frequency. When males were singing and their song overlapped, the largest male could out-compete the other males at the colony by changing how loud and how deep his lowest peak frequency was.[5]
The Montezuma oropendola is a quite common bird in parts of its range. They are omnivorous and are often seen in small or larger flocks foraging in trees for small vertebrates, large insects, nectar, and fruit, including bananas, Cecropia spikes, gumbo-limbo (Bursera simaruba) and Trophis racemosa (Moraceae).[6] Outside the breeding season, this species is quite mobile, with some seasonal movements.
The Montezuma oropendola inhabits forest canopy, edges and old plantations. It is a colonial breeder and only the females build hanging woven nest of fibres and vines, 60–180 cm (24–71 in) long, in a tree that is up to 30 meters high. Each colony has a dominant male, which mates with most of the females following an elaborate bowing display. The female lays two dark-spotted white or buff eggs, and she incubates them without the male until they hatch in 15 days; the young fledge in 30. While the young are still in their nests they are most often fed spiders and other arthropods, frogs, lizards, and fruits. There are typically about 30 nests in a colony, but up to 172 have been recorded.[7]
Although the chestnut-headed oropendola shares much of this species's range, it is smaller, mainly black with a chestnut head (instead of mainly chestnut with a blackish head), and lacks coloured facial patches, so the two oropendolas are unlikely to be confused.
Unlike some populations of its relative, the chestnut-headed oropendola, the Montezuma oropendola does not tolerate brood parasites near their nests. Although Montezuma oropendolas do not have many defenses against Cowbirds, when females see a Giant Cowbird near their own nest they actively defend their nest by attacking the Cowbirds and forcing them to leave their colony. Webster et al. found that the females did not drive the cowbirds away until they were approaching their own nests. This study also found that unlike chestnut-headed oropendolas, the Montezuma oropendolas did not nest near social Hymenoptera. Combined with the fact that Montezuma oropendolas do not allow Cowbirds near their nest, they have no defense against botflies. Nest success is fairly low for the Montezuma Oropendola. The females lay an average of two eggs per nest, but only one is fledged and only one third of the nests in the colonies are successful. Because of their relatively low nest success rate, brood parasites are too high a risk to have around the Montezuma oropendolas nest.[8]
The Montezuma oropendola (Psarocolius montezuma) is a New World tropical icterid bird. It is a resident breeder in the Caribbean coastal lowlands from southeastern Mexico to central Panama, but is absent from El Salvador and southern Guatemala. It also occurs on the Pacific slope of Nicaragua and Honduras and northwestern and southwestern Costa Rica. It is among the oropendola species sometimes separated in the genus Gymnostinops. The English and scientific names of this species commemorate the Aztec emperor Moctezuma II.
