Behavior

Yellow-headed Parrots are often silent in flight. They move quietly through the treetops and fly well above the canopy on shallow, rapid wingbeats (Howell and Webb 1995, Juniper and Parr 1998).

Very few instances of physical aggression involving Yellow-headed Parrots were observed in Tamaulipas, and most of those were interspecific among Amazonas (less than 1% of 3000 nest observations among the three species). Active aggression or defense was limited to a small area around the nesting cavity or tree. The typical cause was an intruder parrot landing or attempting to land on a nest tree (Enkerlin-Hoeflich 1995).

None reported.

Yellow-headed Parrots are observed primarily singly, in pairs or small groups, and rarely in flocks (Howell and Webb 1995), except for larger flocks at communal roosts and favorite feeding stations (Juniper and Parr 1998). For the three Amazona species that he was studying in Tamaulipas, including Yellow-headed Parrot, Enkerlin-Hoeflich (1995) observed that during the nesting period food was uniformly available and parrots foraged independently in mated pairs; in contrast, in the nonbreeding season, pairs converged and foraged in larger groups more widely.

Enkerlin-Hoeflich (1995) observed behavior that he interpreted as socializing, that he acknowledged may have involved aggression or affiliation. Yellow-headed Parrots frequently moved close to the nest of conspecifics and initiated long "vocalization sessions" involving a wide array of vocalization types. They did not exhibit open aggression, but occasional displacement behavior may have indicated subtle aggression. Aggression to defend abundant food sources was not observed; several pairs of the three Amazona species being studied were often observed feeding together in the same tree.

Yellow-headed Parrots roost together in flocks at night. In Belize they roost on pine-covered ridges and move to nearby humid forest to feed; (Juniper and Parr 1998). A study in Guatemala (Eisermann 2003) found them roosting in an isolated stand of mostly-dead mangroves (20 m tall) on the beach surrounded by the sea and swamp shrub. They were observed using trees 10-50 m from the waterline. This was a traditional roosting site that had been used by the parrots for more than 10 years according to locals; it was located about 13 km from the core area of reproduction. Parrots arrived in pairs or groups of three at the roost site about 45-80 minutes after sunset, congregating in the upper canopy of 7-10 mangroves. At this site 60-68 individuals were recorded. On occasion the Yellow-headed Parrots shared their roost site with several Red-lored Parrots (Amazona autumnalis) and Brown Pelicans (Pelecanus occidentalis). Lousada and Howell (1996) reported a roosting flock of about 75 hondurensis at a slightly elevated patch of trees amid cleared agricultural land in the Sula Valley; they also assembled in loose conjunction with about 30 Red-lored Parrots. In the Tres Marías Islands, a flock of twenty were observed roosting in a heavy stand of agave. They would arrive in late afternoon, initially perching on tall flowering stalks and then descending into the lower spiny leaves to within 2 m of the ground, where they remained all night. During the day they would return to forage on the forested slopes of the island (Stager in Forshaw 1977).

In Tamaulipas, at least five pairs of Yellow-headed Parrots exhibited mate fidelity between two nesting seasons, and of these, three exhibited mate fidelity among 3 nesting seasons. Three instances of helpers at the nest, or what he called "trios" or an "accessory bird" were observed. In one case numerous observations (n=17) indicated that the helper participated minimally in nesting and brooding; primarily it flew with the nesting pair and did not enter the cavity, although once it transferred food to the brooding female (Enkerlin-Hoeflich 1995).

Although predation by indigo snakes (Drymarchon corais) was documented for Amazona nests in Tamaulipas (Enkerlin-Hoeflich 1995), none were specifically documented for Yellow-headed Parrots. During measurements of these Amazona chicks, he observed that some chicks were found to have hundreds of ectoparasites attached and engorged with blood; these were identified as a macronyssid mite (Ornithonyssus bursa).