Montezuma Oropendola

Psarocolius montezuma

eBird gives this brief description of the Montezuma Oropendola:  Spectacular, very large ‘blackbird’ of tropical lowlands. Favors forest edge, open woodland, plantations, semi-open areas with trees; colonies of large pendulous nests adorn tall trees. Male is much larger than female, but sexes look similar: dark rusty overall with a black head, bold yellow sides to the tail, and ornate face and bill patterning. Flies rather directly, with slow, ‘rowing’ wingbeats. Memorable gurgling song sounds like water poured from a bottle.  The Birds of the World site provides this interesting information about this bird:  Montezuma Oropendola is a familiar bird on the Atlantic slope between eastern Mexico and extreme western Panama; it also is found on the Pacific slope in Nicaragua and in northwestern Costa Rica. This large bird often is common at the edge of humid lowland forests, and in adjacent second growth and plantations. Montezuma Oropendola nests colonially, often in isolated large trees; such a setting makes the clusters large, hanging, basket-like nests even more conspicuous. Montezuma Oropendolas nest in colonies (multiple nests in one tree or adjacent trees). The average number of nests in these colonies is 24, but ranges up to 130 (Webster 1994a). Webster observed that 88% of nests were in distinct clusters, and that the ones that were not seemed to have some sort of pattern to them (the nest were not randomly built in places). Montezuma Oropendolas are highly dimorphic in size; males may be up twice the weight of females. This species is polygynous, and dominant ‘alpha’ males perform most copulations at a colony (although subordinate males apparently are able to copulate with some females, presumably away from the colony and the presence of the alpha male). The loud, gurgling song of the male is given as the male bows forward, cocking the tail and spreading the wings. Montezuma Oropendolas usually forage in small groups in the canopy, searching for fruit and large insects; at least occasionally they also eat small vertebrates. Montezuma Oropendola easily is recognized by its large size, chestnut body plumage, yellow outer rectrices, bicolored bill, and the pale patch of bare skin on the sides of the head.

I saw my first Montezuma Oropendola on the campus of the University of Costa Rica in San Jose on the morning of Saturday, February 4, 2023.  Our guide Diwö showed us a group of nests, and there were a number of birds noisily flying to and from the nests.  The early morning light was not good for photography, but I was able to get some passable shots.  I ended up seeing more of this bird later in my trip and got some better photos, which I will post as I work on the my blog for this trip.