The yellow-shouldered blackbird forages both in trees and on the ground (6), using separate techniques for the different locations (3). This species congregates at communal feeding sites during the non-breeding season (2) (7), and feeds mainly on arthropods, particularly moths and crickets, as well as seeds and nectar (3) (8). During the nesting season, the yellow-shouldered blackbird stays close to the nest and therefore typically forages in the sub-canopy of trees, in pastures alongside mangroves and in the mangroves themselves (3).
The male yellow-shouldered blackbird returns to the breeding site around six to ten weeks before the beginning of the breeding season. The yellow-shouldered blackbird is monogamous and will usually return to the same site each year in order to pair up with the same mate (3). The male stands on the edge of the previous year’s nest and displays to the female. Once paired, the male will follow the female persistently until the female leaves the nesting grounds (3). The female builds or repairs the cup-shaped nest in preparation for the egg laying (3) (4) (6). An average clutch contains three eggs, and incubation starts after the second egg is laid. The female will incubate the eggs for between 13 and 16 days, during which time the male will bring food back to the nest. The Males roost communally and forage during the day (3). Once the eggs hatch, the male and female yellow-shouldered blackbirds share feeding of the young, both in the nest and after fledging (3).
The yellow-shouldered blackbird will engage in communal mobbing to defend against predators. Most often the male birds do this in order to protect females and their eggs, with many individuals physically attacking intruders or predators (3).