By Karen T. Mabb
Reprinted courtesy of AFA Watchbird Magazine, Jan/Feb 2001
A stir and murmurs… as the first rays of the sunrise gently kiss the tops of towering eucalyptus… an explosive cacophony of green squawking birds with wings aflutter as they exit the roost for their daily foraging foray. Eucalyptus—Australia? No. Green squawking birds—Mexico and Central and South America? No. This is a scene witnessed every morning in Temple City and Arcadia, right in the confines of the lush forests of street and backyard trees, suburban Los Angeles, California, USA.
Many urbanized and suburbanized areas around the world that are already home to many introduced species, such as House Sparrow (Passer domesticus), European Starling (Sturnus vulgaris), Spotted Dove (Streptopelia chinensis), and Rock Pigeon (Columba livia), have become faced with a new invader—parrots. In the San Gabriel Valley, which is where Pasadena is located, parrots have flourished, establishing self-sustaining populations, with reproduction occurring in the wild, well outside of captivity.
The exact location of the parrot roost, where they sleep for the night, changes with the change in season. In the winter, parrots converge nightly on one roost location, easily numbering over 1200 individuals and settle on broadleaf evergreen trees, such as eucalyptus, oak, and fig, since there are not many choices for suitable roost trees. An especially interesting winter roost site is in a stand of Indian Laurel Fig (Ficus microcarpa) trees in the brightly-lit parking lot of a busy supermarket. When spring comes, the roosting flocks decrease in size, but spread out in area, ranging from Arcadia to western Pasadena. The roost flock breaks up into smaller and smaller flocks, because the parrots are tending to choose to roost in newly leafed-out deciduous trees, such as Western Sycamore (Platanus racemosa), Sweet Gum (Liquidambar strycaflua), and Silver Maple (Acer saccharinum). Parrots are also in smaller roost flocks in the spring and summer because they prefer roosts closer to their nesting locations. Parrot chicks reach their peak in September, making up over 10% of the flock (roughly equivalent to over 50 chicks in a flock of 500).
We categorize the free-flying parrots into five major groups: “amazon”-type, “conure”-type, Rose-ringed Parakeet-type, Brotogeris-type, and “other” (macaws, cockatoos, cockatiels, budgies, etc.). The majority of Amazona are Red-crowned (Amazona viridigenalis) and Lilac-crowned (A. finschi) parrots, but small numbers of Blue-fronted Parrot (A. aestiva), Red-lored Parrot (A. autumnalis), White-fronted Parrot (A. albifrons), and Yellow-headed Parrot (A. oratrix) have been documented as breeding, too. Mitred Parakeet (Aratinga mitrata), Red-masked Parakeet (Aratinga erythogenys), White-eyed Parakeet (Aratinga leucophthalmus), Blue-crowned Parakeet (Aratinga acuticaudata), and Black-hooded Parakeet (Nandayus nenday) are the “conure”-sized parrots. They are present in the eastern and far southwestern portions of the valley. Yellow-chevroned Parakeets (Brotogeris chiriri) and Rose-ringed Parakeets (Psittacula krameri) are also found throughout the area. Yellow-chevroned Parakeets tend to be found in botanic gardens (e.g. Huntington Library and Los Angeles County Arboretum) because of their dependency on Silk Floss (Chorisia speciosa) trees as a food source. A flock of less than 20 Rose-ringed Parakeets is often present in the Amazona roost.
Parrots are sustained and thriving due to the prevalence of exotic plantings, especially fruit trees and street trees. When considering parrots as successful urban colonizers, it is important to consider cities as habitat. There are many common characteristics among city habitats. Most cities contain natural waterways like creeks, rivers, etc. Often these waterways are human-altered into concrete washes, flood control channels, debris basins, and reservoirs. Natural habitat is often entirely replaced with exotic vegetation, which is generally clumped into groves and stands due to both homeowner and city planning preference for particular species. The well-groomed city has little under-story and trees are pruned frequently. Backyard fruit trees and remnant orchards are often abundant and provide a source of food for many types of animals. Cities have structures such as buildings, power lines, power poles, radio towers, and highways, which act as barriers to animal movements and sources of mortality, but are also utilized as nest sites, roosts, cover from predators, and perches for predators.
Among our research priorities is to develop a method to accurately estimate the size of this population and to assess its rate of growth. We are also interested in the frequency of interbreeding between closely related congeners (Mitred Parakeet/Red-masked Parakeet, Red-crowned Parrot/Lilac-crowned Parrot, White-winged Parakeet (Brotogeris versicolurus)/Yellow-chevroned Parakeet), which are geographically separated in their native areas. We are attempting to determine the factors that lead to successful colonization by analyzing community structure and habitat. Perhaps this information could be applied to assist conservation in endemic areas. Likewise, we are researching the extent of pressure these parrots are exerting on native animals, especially native cavity-nesting birds.
I hear all of the time how people would love to catch one of these parrots. It takes a certain kind of person to even put up with a TAME parrot (in my opinion: (1) one who is hard of hearing, (2) eternally patient, and (3) has no fear of losing beak-sized chunks of flesh and/or those unnecessary fingers). Wild parrots do not make good pets. Many of the wild parrots are out there in the first place because their owners could not stand them and threw them out of the nearest window, despite the hundreds of dollars they spent on them. They are messy, noisy, and these wild parrots can carry many diseases and parasites. I also hear rumors of people cutting into nest cavities and taking chicks. The destruction of nest cavities for the purpose of harvesting chicks is one of the reasons parrot populations are in such peril in areas where they are endemic. Cutting open cavities affects the health of the tree and destroys the cavity FOREVER, rendering it useless for parrots and, more importantly, for native animal species.
As beautiful and charming as parrots are, we must not let that cloud us into taking light the threat they pose. Should parrots move out of the city and invade wild land, such as sycamore and oak canyons, they could exert serious competitive pressure on native species. These native species populations already suffer under the pressure of increased urban- and suburbanization. As areas undergo this transformation into urban-sprawl, and as the trees in these neighborhoods grow into “mature forest”, we can expect that it becomes more common to see free-flying parrots established in other city areas in addition to Los Angeles County, or even California.
C/O The California Parrot Project
P.O. Box 153
Weldon, CA 93283-0153
Tel: (626) 355-9412 (Pasadena Audubon Society)
Web address: http://www.parrotproject.org
· Karen started working on Parrot Project in 1995 while a student at California State University, Long Beach, and is joined by (and could not possibly do without) Natural History Museum of Los Angeles County ornithologist Kimball L. Garrett and California State Polytechnic University, Pomona, biology graduate student Melanie A. Stalder. Karen is now a student at California State Polytechnic University, Pomona. Parrot Project is affiliated with the Natural History Museum of Los Angeles County and California State Polytechnic University, Pomona and operates in cooperation with Pasadena Audubon Society (who handles all inquiries and donations). Parrot Project is also associated with Dr. Walter Piper (Parrot Project of Orange) of Chapman University, and Alison Sheehey (Parrot Project of Bakersfield).
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The new Parrot Project went on-line November 2, 2000.