Graduation Date
1981
Document Type
Thesis
Program
Other
Program
Science
Committee Chair Name
Dr. Stanley W. Harris
Committee Chair Affiliation
Cal Poly Humboldt Faculty or Staff
Second Committee Member Name
Dr. Richard Botzler
Third Committee Member Name
Dr. James Smith
Keywords
Science
Subject Categories
Natural Resources
Abstract
Feral populations of three parrots species. Amazona oehrocephata^ A. viridigenatis ¿ and A, fins chi were studied to describe ecological aspects of their existence in southern California. This study focused on ecology of roosting, foraging and nesting in the species in the San Gabriel Valley. Populations of A. viridigenatis and A, finschi shared a 44 sq km home range. There was evidence for close interspecific behavioral synchrony and social cohesion between these two species. In contrast, groups of A. ochro- cephata were independent physically and socially from the two other species. Amazona viridigenatis and 4, finschi roosted consistently in a 110 ha area of the home range. Parrots usually selected large Fraxinus vetutina trees for roost sites. Most foraging activity occurred in the morning and evening. Foraging group size decreased in spring and early summer, and increased in fall and winter. Foods included seeds, fruit and flowers of at least 34 tree and shrub species. Jugtans regia and Liquidambar styraciftua were the species used most commonly as food. Four pairs of feral parrots nested successfully in 1977. All nests were located in a 50 ha park and garden area. Nests were in arboreal cavities in palm and gum trees. iii iv Nesting pairs displayed long-term nest-site tenacity and were territorial against conspecifics and congenerics around the nest tree. Both parents of each pair attended the nest together daily throughout the nesting period. Both parents abandoned nests containing eggs and young overnight on several occasions, but returned early in the morning to incubate the eggs, or brood and feed the young. Only the female incubated. Incubation was estimated roughly at 25-30 days for A, vlrldigenabis an&Jl. finschi. Nestling life was at most 55 days. The estimated 40% fledgling loss after one month was attributed to capture by humans, dog and raptor predation and unknown causes. Parrots did not compete seriously with native bird species for food and nesting resources. Parrots did not forage on commercial tree crops, and were essentially restricted to suburban habitat. Parrot population growth and range expansion are limited by low availability of nest sites and possible behavioral attachments of present populations. Protection of parrots is recommended to preserve unique research values of feral populations for conservation of natural populations.
Recommended Citation
Froke, Jeffrey B., "Populations, Movements, Foraging and Nesting of Feral Ama Zoma Parrots in Southern California" (1981). Cal Poly Humboldt theses and projects. 2409.
https://digitalcommons.humboldt.edu/etd/2409