Studying the breeding biology of Amazon parrots in captivity presents special resource problems. The birds are expensive to acquire-if available at all. They require considerable space to house and must be rigorously quarantined prior to introduction to a general flock. Further, wild-caught Orange-winged Amazons (Amazona amazonica), the species that the Psittacine Research Project (PRP) is studying, are considered difficult to breed, often requiring several years in captivity before egg-laying begins; and standard protocols for breeding these birds are not established, although some aviculturists have had excellent success and contributed invaluable advice to our project.
Given these constraints, and aware that scientific data needs to he gathered as rapidly as possible due to the growing number of endangered parrot species, we adopted experimental protocols that attempted to maximize information yield from a small population of non-breeding Amazons. We employed a multi-faceted management plan as an environmental probe to detect manipulations that might stimulate reproduction. Our results reflect the compromises that small numbers and lack of light and temperature-controlled facilities impose, but the initial results are extremely encouraging.
In the 1990 breeding season a group of eight self-selected pairs of wild-caught Orange-winged Amazon Parrots housed in wire cages (0.9 by 0.9 by 1.8 m [3 x 3 x 6 feet] ) were provided with nesthoxes in midFehruary to encourage breeding. Detailed behavioral observations were made by video-taping and direct ohservation to compare the incidence of several behaviors hefore and after nest-box presentation. The results of this experiment, conducted hy Lisa Jochim, a graduate student now heginning veterinary school at UC Davis, will he reported on at a later date. We here treat this group as a control for comparison with the "enriched" group described below.
Seven other pairs in an environmentally enriched group were provided with four additional environmental manipulations:
1) Enriched pairs were first separated into two same-sex flocks (flight dimensions, 12 m by 8 m by 7 m (39.36 x 26.24 x 22.96 feet] ) for three months, then reunited (with their original selfselected mates) and placed in wire cages with nest-hoxes as above in mid-March.
2) Pairs were also provided with nest-boxes that had wooden inserts that reduced the diameter of the nesthole (from 4.5 cm to 3.5 cm [l.75-1.37 inches] ) and permitted pairs to "chew" into the nest-box.
3) Enriched pairs were also, at the time of reuniting and nest-box presentation, offered two items of fruit ( 1/ 4 apple and 1/4 orange) five days per week.
4) They were exposed to a spray of water from ceiling misters on alternate days for a period of ahout 15 minutes twice a day.
Behavioral observations of these birds, recorded by Tracy Brownhack, a graduate student also heginning veterinary school at UC Davis, will likewise he reported at a later date.
Both the control and enriched groups were housed in cages in a semi-enclosed facility which exposed them to natural direct and indirect lighting and daylength. Cages were aligned on either side of a central aisle. Feed hoppers, with a 20% protein pelleted diet, and automatic waterers were affixed to the front of each cage. Nest-hoxes were attached to the rightrear side, and visual harriers occluded the hack half of each cage (on the nestbox end) from adjacent cages.
One out of eight pairs produced eggs in the control group, with four eggs hatching. Six of seven pairs in the enriched group laid eggs (mean clutch size 3.66 plus or minus .21 S.E). Two laid infertile clutches of four eggs The other four pairs produced from one to four nestlings each.
Despite the impressive percentage difference (86% of enriched pairs vs 12.5% of control pairs: P<0.05, chisquare), the small number of pairs provides only a weak statistical basis to conclude that pairs in the enriched group were more likely than controls to lay eggs. Nonetheless, this view is supported by behavioral differences between the groups: irrespective of breeding activity, pairs in the control group showed more intercage aggression in the form of tail fanning displays and high-intensity vocalizations.
Comparison of these treatments as a single experiment must be done with caution: nest-boxes were presented at slightly different times and the simultaneous....