RSCF has been non-invasively monitoring wild Green-cheeked Amazon parrots on Palm Beach, FL since 2000. This unusual population has only a single breeding site here – a 150-year-old stand of ornamental Casuarina (Australian pine). The birds provide a convenient study system for researching the ecology of non-native parrot species, as they also provide insights about how small parrot populations persist in a continually perturbed, urban environment.
Amazona viridigenalis is native to east-central Mexico, where it has steadily declined for the past 30 years due to capture for the pet trade and habitat loss. Listed as CITES Appendix I (international), it is considered by the IUCN and Birdlife International to be globally endangered, with wild population strongholds outside of its native range in southern California and south Florida. The Palm Beach A. viridigenalis population pre-dates the advent of commercial aviculture, and was well established long before the importation of Mexican Amazon parrots for the pet trade, which hit its zenith in the early-to-mid 1980’s. While established feral populations of Green-cheeks in California can be directly traced to releases from import stations and households, the Palm Beach population likely has its roots in a single, pulse-release of wild-caught birds sometime during the 1940’s. The Green-cheeked Amazon is perhaps the only endangered parrot to be best represented in the wild as a non-native, and has become a species of special concern even among ardent in situ conservationists. In California, A. viridigenalis has been added to a special state bird list, affording it specific legal protection. Presently, no equivalent statutes pertain to this species in Florida. As in California, this parrot seems not to displace or compete with native wildlife. On Palm Beach, the population of 100-150 individuals has been more-or-less static for decades, and breeding is completely dependent on naturally forming cavities within a row of old-growth Casuarina that were planted as ornamental vegetation during the 1860’s along the original road to the Breakers Hotel and Casino. No other suitable nesting trees appear to be available to the species in south Florida.
In mid-April of this year, 14 or more Green-cheek pairs attempted nesting and laid eggs (2-3 per clutch), but only six nests supported chicks that survived at least through the pinfeather stage (4 weeks). Successful nest cavities ranged from 4-8 meters off the ground, and 0.5 – 3 meters depth, all with entrances no more than 0.3 meters wide; orientation was north, south or east. Nest failures were especially high during the incubation and early post-hatching periods. All eggs and/or small chicks from shallow (< .3 m), or exposed (>.5 m-width entrance) nest cavities suffered predation from raccoons, crows or starlings, or abandonment by the parents, which may have been due in part to heavy rains early in the season. The entire breeding population is concentrated within two parallel lines of trees less than 400 meters long, and intense competition for nest cavities and vicious territorial bouts are evident. Interestingly, there appears to be a short, second breeding effort in this flock, commencing in early June just as chicks from other nests are nearly the fledging stage. We suspect that this late nesting activity is either the result of breeding pairs with failed nests trying again, or new pairs defending and occupying fresh cavities.
In total, seven chicks fledged successfully from 19 June – 10 July, and two from one nest were flooded out of their cavity within a few days of fledging, and were rescued. None of the late nesting attempts proved successful.
The feral parrot flock on Palm Beach is unusually diverse, with a total of seven parrot species documented: four Amazona species (Green-cheek [A. viridigenalis], Orange-wing [A. amazonica], Double-yellow Headed [A. ochrocephala oratrix], and Blue-front [A. aestiva]); two conures (Blue-crowned [Aratinga acuticaudata], Red-masked [Aratinga erythrogenys] and the ubiquitous Quaker Parakeet (Myiopsitta monachus). All of the Amazon species comingle to some extent within the breeding Green-cheek population, and at least one successful nest was the result of hybridization (between the Green-cheek and Orange-wing).
Judging from the excellent condition of chicks, parents appear to have little difficulty locating food, primarily Ficus and palm fruits, mango, guava and late citrus. During the non-breeding season, the parrots congregate en masse on Casuarina, Ficus and palm trees, and provide a raucous spectacle for onlookers.
We look forward to reporting on the Palm Beach parrots throughout the year.