SPECIES

Olive Oropendola Psarocolius bifasciatus Scientific name definitions

Harold F. Greeney
Version: 2.0 — Published June 10, 2022

Breeding

Introduction

The Olive Oropendola is a colonially nesting species that constructs long, pendant, pouch-like nests that hang in clusters from the tips of branches in canopy emergent trees. Despite its wide range, the architecture of its nest remains poorly described and the eggs have not been described at all. See also Behavior: Social and Interspecific Behavior and Sexual Behavior.

Phenology

In general, the seasonality of nesting is poorly known in most parts of the range of this species. For the widespread subspecies yuracares most seasonal information is available from Bolivia, with scattered reports elsewhere. In Venezuela, nesting appears to coincide with the dry season, from January to April, but this is largely based on observations at only two colonies (192). In Ecuador, an active colony was reported in mid-January (58). In southwestern Brazil (Acre), a dependent fledgling was reported near the end of May (160). In Bolivia, there are reports of displaying males at two localities in July, with associated female beginning to build nests at one of these (5). At another colony in Bolivia, active at the end of August, at least some nests were still under construction, while others contained nestlings (5). Also in Bolivia, an active colony was found near the end of November, and a large colony observed during mid-October had at least four nests under construction, with many others with eggs or nestlings (5). The scant observations available on the nominate subspecies include only the report of an active colony near San Antonio do Prata in February (196).

Nest Site

Microhabitat

In most colonies, it appears that nests are built near the tips of branches and are highly visible (196, 178). For one colony sited in a Socratea palm, the nests were well hidden from view by the large palm fronds (5).

Site Characteristics

Nests are generally situated at mid- or upper-canopy levels in tall trees with isolated trees, frequently at forest edges or above areas with low or broken canopies (196, 178, 146, 160). Dead or leafless trees seem to be preferred (196); however, there are reports of birds using Socratea palms (n = 2), an unknown leguminous species (c.f. Dypterix sp.) (5), and Erythrina trees (n = 2; 192). A Bolivian colony in the legume tree contained two clusters of c. 30 nests and was at the bottom of a steep-sided valley near agricultural fields and adjacent to a stream (5).

Nest

Construction Process

Based on observations of subspecies yuracares in southern Venezuela, Rodríguez-Ferraro (192) noted that while females are nest building, males spend the majority of daylight hours resting, displaying, or preening. Once females approach nest completion and prepare to lay eggs, the males’ rate of display increases dramatically and tends to take place at the nest site rather than from the perch they occupied during early nest construction.

Structure and Composition

The nest of the Olive Oropendola, like those of other oropendolas, is pendant, enclosed, pouch-like structure, with an entrance near the top, and built of tightly woven fibers. Compared with the nests of other species; however, available nest descriptions are relatively poor, and the nest of Olive Oropendola still deserves a formal, quantified description. The nests of subspecies neivae have been described simply as elongated bags more than 50 cm long (196). Interestingly, the nests of subspecies yuracares in Bolivia were noted to be easily distinguished from the nests of sympatric Crested Oropendola (Psarocolius decumanus) (5). These authors stated that, while nests of Crested Oropendola were neatly woven and elongate pyriform in shape, the nests of Olive Oropendola were more noticeably more cylindrical, built of coarser fibres, and tended to be more thickly clustered (each nest less isolated within the colony). The relative sloppiness of the weave, though not the cylindrical shape of Olive Oropendola nests can easily be seen in the photograph provided by Lima et al. (160). The cylindrical shape, however, is more easily observed in the other photos (197).

Maintenance and Reuse of Nests

At least in some cases, nest trees may be used year after year (2, 192).

Eggs

Apparently not described.

Incubation

Parental Behavior

Incubation is performed by females, but otherwise unstudied (2).

Hatching

No information.

Young Birds

No information.

Parental Care

No information.

Cooperative Breeding

No information.

Brood Parasitism by Other Species

There are no records of brood parasitisim on Olive Oropendola, but Fraga and Kreft (5) observed both sexes attacking a pair of Giant Cowbird (Molothrus oryzivorus) that landed near an active nest colony in Bolivia.

Fledgling Stage

No information.

Immature Stage

No information.

Recommended Citation

Greeney, H. F. (2022). Olive Oropendola (Psarocolius bifasciatus), version 2.0. In Birds of the World (B. K. Keeney, Editor). Cornell Lab of Ornithology, Ithaca, NY, USA. https://doi.org/10.2173/bow.olioro1.02