Montezuma Oropendola
From Costa Rica Travel Guide: Vacation and Travel tips
Montezuma Oropendola
Montezuma Oropendolas are found from southern Mexico to central Panama. In Costa Rica, they inhabit many parts of the country, most noticeably, in tropical lowland forest and secondary forest, to approximately 3,000 ft. Oropendolas tend live in regions near water and clearings, and nests are not usually found deep in the forest. Frequently, they can be found close to banana plantations, bamboo thickets, forest canopy edges and old plantations. Tall dicotyledonous trees are usually chosen for nesting, but in the absence of these preferred trees, oropendola nests have been observed in a variety of trees.
The Montezuma Oropendola is a large bird, especially when compared with other species of oropendolas, and the males are considerably larger than the females. Males will average 20’’ in length (50cm) and weigh over 18 ounces (520 gm), while the females are 15’’ (38cm) and weigh about 8 ounces. Both the adult male and female oropendola are mostly deep chestnut in color with a blackish head and rump with a show-off tail that is bright yellow. There is a bare blue cheek patch and a pink wattle that almost seems out of place. Their sharp bills are black and orange, and in males, the orange extends over their forehead. Juveniles are similar in appearance except the colors are duller.
Montezuma Oropendolas are mainly fruit eaters, but they are also known to eat flowers from open grasslands, small vertebrates, nectar, and larger insects. Females usually forage away from the colony in small groups, while the males tend to forage alone. Oropendolas will feed throughout the day, but at dusk will return to their colony. A single tree can have upwards of 60 nests, but typically the number is approximately 30-40. Nesting trees are characteristically tall, wide and isolated trees (so that it is difficult for monkeys and other arboreal predators to get to them). Nests, typically woven by the females, are large, measuring 4-6 ft. long when completed. The females use banana fibers, vines and twigs- the process takes about 10 days. When finished, these nests are suspended from tips of branches, appearing like ‘overgrown, gourdlike fruits.’
During the breeding season (January to May) they are highly colonial and highly polygamous; as successful males mate with several different females during this time. The males
Males have an elaborate courtship display: they bow forward (sometimes executing a complete somersault) pointing their bill downward, and fan their tail, all the while making loud gurgles and bubbling sounds. Before mating, the male moves around the female and pecks her tail feathers, ruffling and spreading them. If the female is interested, she will stick around and the male will mount and begin to mate.
Females usually incubate 1-2 dark-spotted white or buff eggs for approximately 15 days before they hatch. Males guard the nest. Fledging occurs 15-30 days after hatching and juveniles reach sexual maturity in less than 1 month, but will not mate until the next year. Often prey to the likes of toucans, snakes, monkeys and botfly larvae- the mortality rate is high in oropendolas. Although females will mate up to three times during the season, a small percentage of chicks will actually survive through the hatching period.
