Detailed descriptions of species foraged and parts of fruits utilized in its native Ecuadorian and Peruvian ranges are limited, though foraging on Saponas purpurea (Anacardiaceae) (drupe with large seed and watery fleshy pulp) - pulp eaten but not seed and Hyeronima alchorneoides (3 mm drupe with single 1.5 mm seed) - seed cracked and eaten, does occur (Best and Clark 1991). In coastal valleys of Peru A. erythrogenys regularly fed upon Ceiba trischistandra Bombacaceae (crack seeds of multi-seeded capsule), Bursera graveolens Burseraceae (one to five seeded drupe), and Eriotheca ruizii Bombacaceae (crack seeds of multi-seeded capsule). A. erythrogenys frequently visits Erythrina sp. flowers but there is no detailed information on the birds’ effect on the flowers (Best et al. 1993, 1995). For perspective, Crimson-fronted Parakeet (Aratinga finschi), which is closely related to A. erythrogenys, and Dusky-headed Parakeet (Aratinga weddellii) non-destructively nectar forage on Erythrina poeppigiana (Skutch 1983) and E. fusca (Cotton 2001) flowers, respectively, and are both likely to be pollinators of these plant species (Cotton 2001).
Naturalized populations in California and Florida, USA, readily use artificially-provided bird seed at bird feeders (Garrett et.al. 1997, Bittner 2004), whereas the Honolulu Hawaiian population is not known to utilize bird feeders. According to Bittner (2008) the San Francisco population does not rely upon food supplementation to survive and reproduce. Foods eaten by A. erythrogenys in California include: Plantanus spp., Plane tree; Myoporum laetum, Mouse hole tree; Cotoneaster sp., Cotoneaster; Celtis sp., Hackberry; Eucalyptus sp., Eucalyptus; Tecomeria capensis, Cape honeysuckle; and commercial bird seed (Mabb 1997). Although several species of figs were present, including Ficus macrophylla, Moreton Bay fig, A. erythrogenys was not observed to feed upon it from data collected over an approximately year long period (Mabb 1997). Bittner (2004) reports that A. erythrogenys feeds upon Juniperus, Juniper seed cones; Pinus canariensis, Canary Island Pine nuts; Malus domestica, apples; Eriobotrya japonica, Loquat; Psidium cattleianum, Strawberry guava; Pyrus communis, pears; Cotoneaster frigidus, Cotoneaster seeds (pome, 1-3 seeds); Crataegus monogyna, Common hawthorn seeds and pulp (pome, 1 seed).
In Honolulu radio-collared Aratinga erythrogenys and flock mates followed continuously for complete days fed upon (in order of frequency) Prosopis pallida, (destroy mature, unripe seeds and eat legume pulp); Cordia sebestena, (destroy unripe seed); Psidium cattleianum, (specificially destroy mature seeds one by one); ripe Mangifera indica pulp; Carmona retusa, (destroy mature seed); Celtis sinensis, (destroy mature seed); rare feeding on Pithecellobium dulce, (destroy unripe seeds and eat legume pulp "aril") and Casuarina spp., (remove capsule and probe for seeds). The majority of foraging by nesting birds was on Prosopis pallida green legumes (seeds) and Cordia sebestena. Cordia subcordata, Kou/Smooth Cordia, was never eaten even when next to Cordia sebestena.
Radio collared Aratinga erythrogenys (and flockmates) in Honolulu never decended to the ground to forage or drink and appeared to drink from the canopy flowers of Spathodea campanulata trees and occasionally dismembered Samanea saman, flowers. In either case, flower visiting was an irregular activity, unlike regular foraging activities. The parakeets were attracted to flowering Erythrina sandwichensis, but only while in bloom; once trees went out of flower A. erythrogenys did not visit this tree species for its legumes. Visited flowering trees did not appear to have fewer flowers than non-visited trees. After over 1000 hours of all day continuous observation of radio-collared parakeets over eight months it was found that many other plant species with abundant fruit were not eaten, such as: Leucaena leucocephala, Ficus microcarpa, Ficus macrophylla, Samanea saman and Cordia subcordata.