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The Psittacine Research Project
Ann T. Brice, Ph.D. and James R. Millam, Ph.D.
Psittacine Research Project
Approximately one-third of the Neotropical parrots are threatened or endangered, and the others are virtually all considered to be in some state of decline. Similar patterns have been projected for psittacines worldwide. Habitat destruction remains the largest single cause of the decreasing populations, but excessive collection pressure for the international pet trade is also a significant factor for some populations. The Psittacine Research Project (PRP) seeks to address the critical state of parrots in the wild and the growing interest in keeping psittacines as pets by conducting basic and applied research both in captivity and in the parrots' natural habitats. I spoke to you yesterday about our research on the Yellow-naped Amazon in Guatemala, and today I would like to focus on our work at the university.
The Avian Sciences Department acquired its first colony of psittacines in 1979 in response to student interest in the biology of exotic birds. Cockatiels (Nymphicus hollandicus) were selected as model species for instruction and research because of their population status, size and availability. Initial studies focusing on nutrition and basic management provided research opportunities for a growing number of undergraduate and graduate students. The colony served as an integral part of Dr. C.R. Grau's course on exotic bird management. Research by Dr. Grau and T.E. Roudybush led to the development of the first experimentally tested diets for the hand-rearing and maintenance of exotic birds and resulted in numerous technical papers on the nutrition and husbandry of Cockatiels. Husbandry research included studies of optimal cage and nest box size for a research colony, egg storage times and incubation parameters for Cockatiels. Nutritional research included studies on protein and water requirements for growth of chicks, requirements for other nutrients such as lysine, calcium and fat and the relationship between nutrition and weaning.
Dr. J.R. Millam began work on Cockatiel reproductive physiology and behavior in the mid-1980s. He and his students published several papers on reproductive hormones and their influence on the Cockatiel breeding cycle. Among the titles were: "Reproductive Success of Hand-reared vs. Parent-reared Cockatiels", "Reproductive Behavior and LH Levels of Cockatiels Associated with Photostimulation, Nest-box Presentation and Degree of Mate Access" and "Reproductive Activity of Force-paired Cockatiels".
We currently maintain a flock of 200-300 Cockatiels and are always looking for new research opportunities. We unexpectedly found one a few years ago when we noticed that about25% of the breeding females were laying their eggs on the cage floor instead of in the nest box. We offered an experimental group of floor layers a choice of the regular small round opening nest box or an open shelf model. They chose the open shelf and then in subsequent trials moved to the traditional box. The results indicated that chronic floor laying can be corrected by offering Cockatiels shelf-type boxes and that these boxes may also be useful for improving captive reproductive performance of non-layers and naive layers.
Our most recent studies with the Cockatiels include research on the embryonic development of the immune system, the role of stress and the immune system, the effects of a synthetic hormone in stopping breeding in chronic layers and the effects of prolactin, a reproductive hormone, in improving reproductive success.
Acquisition of Orange-winged Amazons
In 1983 a colony of Orange-winged Amazons (Amazona amazonica) was added to the collection. The fifty birds were part of a large shipment imported from Guyana. Some were identified as immature, but the majority were of unknown age. This species, although not yet endangered in the wild, is a good model for many that are. Orange-wings were known to be unreliable breeders in captivity and represented a new challenge for the project's research effort. The birds underwent a lengthy period of quarantine, health checks, and housing changes. When they were finally allowed to select mates and were housed appropriately (in 3'x3'x6' suspended welded wire cages), we expected a flurry of reproductive activity, but, in fact, nothing happened.
In 1989 armed with a well studied diet and knowledge of cockatiel reproduction, along with many suggestions from aviculturists, we focused our attention on the as yet non-producing Orange-wings. We presented half the pairs with a series of environmental changes including separation into same sex flights for three months before reintroduction to mates, a wooden insert to be chewed in order to gain access to the nest box, deeper nest boxes, misting, and offerings of fruit. Six of seven of the experimental pairs laid eggs. Clutch size of pairs that laid averaged 3.7+/- 0.2 eggs per clutch. Hatchability was 50%. All but one of the hatched chicks fledged. Clearly the enriched conditions stimulated reproduction, but what particular manipulation or combination of manipulations was responsible could not be determined.
It was not possible to repeat the experiment with naive birds because we didn't have any available, so we flipped the experimental and control pairs the following year. More than half the birds in both groups laid. Clutch size was essentially the same (control = 3.6 +/-0.4 eggs; enriched = 3.5 +/- 0.3 eggs). Hatchability was not different between the two groups, but the overall fledging rate was lower in the second year than the first (66.7% vs. 92.3%) It appears that once the birds obtained the experience of reproduction, the external stimuli were not so critical for success as they had been for first time captive breeders.
In 1992 we were able to move to a remodelled building that allowed us to house the birds completely indoors, as opposed to earlier housing in partially enclosed flights. Then we able to control lighting conditions to test the influence of long daylength stimulation. Eight pairs per room were held in breeding cages and kept under short days (10L:14D) Daylength in one room was then increased to 14L:10D at the time of nest box presentation but kept unchanged in the other. Reproductive performance was comparable under both lighting conditions with several pairs in both groups laying eggs. Hatchability was greater in the photostimulated group, but the small sample size did not permit a meaningful statistical test of this.
Hormone levels during reproduction
During the 1992 season we also collected blood samples for steroid hormone analysis. Estradiol (a form of estrogen) levels in females increased from about 76 pg/ml before laying to over 200 pg/ml during egg laying, and dropped to about 50 pg/ml after laying. Testosterone levels peaked in both males and females during nest inspection, then dropped precipitously and remained low during egg laying, incubation and brooding. Progesterone levels, which were higher in males than females, were moderately elevated during egg laying, incubation and brooding in both sexes.
Taming parent-reared chicks
After watching aviculturists work around the clock to hand-feed chicks so that they could be sold as tame fledglings, we decided to investigate the possibility of taming the chicks while letting the parents raise them. Half the chicks during one breeding trial were handling for 15-30 minutes a day beginning around day 12. This continued daily until fledging and biweekly thereafter.
Tameness of handled chicks and non-handled controls was measured just prior to fledging. The criteria included several behavioral and physiologic comparisons: response to a touch to the hear, respiratory rate, approach or avoidance behavior toward the handler, etc. All tests revealed differences between the two groups. A similar experiment the following year revealed to that essentially identical results could be achieved by handling chicks beginning at about 35 days of age instead of 12.
What long-term effects this handling might have on breeding success is unknown. Like most hand-reared birds, the handled birds did tend to lose their tameness when the handling stopped and they were housed with other unhandled birds. The handled birds that were placed in homes as pets are indistinguishable from hand-reared birds.
Psittacine Research Project Outreach
One of the missions of the PRP is to disseminate the results of psittacine research to the public. We do this through a number of avenues. We publish a newsletter, "The Exotic Bird Report", which is available to all who make donations to the project. The newsletter reports on our research at the university and in the wild, as well as research and news of other parrot biologists. We also produce educational materials. In the early 1990s we developed a poster entitled "Cockatiel Embryonic Development", so that those interested in breeding psittacines would have information about parrot embryonic development rather than having to refer to poultry models. We have begun a "Special Publications Series"; the first in the series was written by Dr. Catherine Toft and is entitled "The Genetics of Captive Propagation: A Manual for Aviculturists". We help people with problems and questions over the phone and via electronic mail and speak at avicultural conferences around the country every year. We also welcome collaboration on psittacine research projects with biologists and veterinarians from other institutions.
One final note: We depend solely on contributions and grants to continue our research at the Psittacine Research Project. Without the support of avicultural organizations and individuals over the years we could not have accomplished what we have. I urge you to to support our efforts, so that we can provide you with the latest research results on captive and wild parrots.