Donald Brightsmith, Ph.D. is a Duke University biologist who is presently working with macaw populations at Tambopata. Although his project does not explicitly involve pionus parrots, there are large flocks of Blue-headed Pionus (P. menstruus) that also visit Tambopata regularly. Additionally, Don's work with artificial nesting structures and nesting site development has perfected techniques which we will soon be employing in Ecuador.
In this paper Don discusses the effectiveness of the macaw reintroduction program. Traditionally, reintroduction programs have not met with much sucess, probably for a variety of reasons, including (but certainly not limited to) chicks imprinting on their human handlers, lack of a natural immunity to bacterial and viral organisms present in their "new" homes, the captive-bred's lack of knowledge about wild nutrition, and difficulties in integrating with extant flocks. Don's discussion is encouraging because of the impact successful reintroductions can have on endangered populations. This paper is printed with Don's knowledge and permission.
Throughout the Neotropics, populations of macaws and parrots are declining due to a variety of factors including habitat loss and collection for the pet trade (Beissinger and Snyder 1992, Enkerlin-Hoeflich and Hogan 1999, González 1998, Horstman 1996, Wright et al. in press). In many areas these forces have reduced macaw populations to dangerously low levels or resulted in their local extinction. As a result of these extinctions, numerous projects have released macaws in to the wild or are planning to do so (Schischakin 2000, Hilburn 2000, Wille 1992).
This report summarizes the results of a hand raising and release project carried out at the Tambopata Research Center (TRC) in Madre de Dios, Peru. TRC is located in the extreme southwestern edge of the Amazon basin at the base of the Andes Mountains. The center is located 50 meters from the Tambopata River deep inside the 1.5 million hectare protected area composed of the Tambopata-Candamo National Reserve and Bahuaja-Sonene National Park. The site is covered with tropical moist forest with a canopy of 30 - 35 meters and occasional emergent trees rising to 55 - 60 meters (Terborgh 1983, Munn et al 1991). The area boasts healthy populations of three species of large macaws, Blue-and-gold (Ara ararauna), Green-winged (A. chloroptera) and Scarlet (A. macao). The center is located a few hundred meters from a large clay lick where up to 250 macaws have been seen coming to take clay (Munn et al 1991). The abundance of macaws in the area makes this site an ideal location to develop new management techniques as there are sufficient individuals to obtain relatively large sample sizes.
Research from 1990-1993 at the site found that in most nests where more than one chick hatches all younger chicks die of starvation (Nycander et al. 1995). The goal of the research reported here is to develop techniques to save these younger chicks that would have died of starvation. Since 1992 a total of 34 macaws have been hand-raised and released at TRC (Nycander et al 1995 and unpublished data). Of these 6 were Blue-and-gold Macaws, 5 were Green-winged Macaws and 23 were Scarlet Macaws. The birds were raised without trying to isolate them from human contact (see Nycander et al 1995 for more details). Since their release some of the birds have continued to return to the buildings at TRC to look for food on an irregular basis. From 26 August - 6 September 1999 and 26 November 1999 - 16 March 2000 observers recorded the date, time, tail condition, band number and species for any macaw that flew in and landed in the lodge buildings. For each bird it was also recorded if they were accompanied by a potential mate.
From 26 August - 6 September 1999 and 18 November - 16 March a total of 11 of the 34 hand-raised macaws were resighted. Of these 2 were Green-winged Macaws and 9 were Scarlets. This indicates that at least 40% of the released Green-wings remain alive (2 of 5 released) and at least 40% (9 of 23) of the Scarlets remain alive. It is certain that not all individuals that are still alive are regularly returning to the buildings at TRC. The evidence supporting this is that two individuals that were known to be breeding within 1 km of TRC were only seen at the lodge once during the entire period of September - March. Of the 11 that were resighted at least 7 were mated with wild birds. Three of these pairs, all Scarlets, were found nesting in artificial nest boxes. A 7 year old and its mate defended a nest box for the entire season but never laid eggs. A 6 year old laid two eggs but the eggs cracked shortly before hatching and well developed embryos were visible. A 7 year old Scarlet laid 2 eggs, both of which hatched. The first chick was found dead within one week of hatching with an empty crop. The second chick hatched and fledged at about 90 days of age.
A total of 6 Blue-and-gold Macaws were hand-raised and released between 1992 and 1994. Of these, none have been seen during 1999-2000. Anecdotal accounts and personal communications from guides and researchers suggest that all these birds began to fly with wild birds and broke their dependence on the food from people at a young age. As a result it is thought that the disappearance of these birds is due to a difference in their behavior not a difference in their survival rates. Unfortunately with no way to know if the birds have survived, this theory cannot be tested.
The data reported here are the first that document the successful integration of hand-raised macaws into a wild population. None of these birds are still receiving a significant portion of their daily nutrition from the lodge. All are feeding almost exclusively on wild food sources in the surrounding forest. Most of the birds that return to the lodge have formed pairs. Also this is the first documented report of breeding in the wild by a captive raised and released macaw. This shows that hand-raised macaws can learn to forage and avoid predators without the help of their parents. It also shows that hand-raised and imprinted macaws can fully integrate into wild populations. The resightings show that 78% of the birds survived the first year (Nycander et al 1995) and that at least 40% of the macaws survived for 5 - 7 years after reintroduction (this study). The high rates of survival reported here shows that releasing hand-raised birds is a viable option in areas distant from hostile human populations.
The survival rates reported here are relatively high in comparison to those found in other releases of psittacids. For example only 1 of 3 hand-raised Puerto Rican Parrots (Amazona vittata) survived the first week after release (Meyers et al. 1996). In Arizona, none of the 23 captive-raised Thick-billed Parrots (Rhynchopsitta pachyrhyncha) survived the first 2 months (Snyder et al. 1994). The only parrot release that reported similar survival rates is for Yellow-shouldered Amazons (Amazona barbadensis) on Isla Margarita, Venezuela where 10 of 12 (83%) survived the first year (Sans and Grajal 1998).
The complete lack of resightings of Blue-and-gold Macaws coupled with their propensity to wander from the lodge and associate with wild birds from a younger age suggests that these birds may have integrated more quickly into the wild population. If this is true, it suggests that the hand-raising may have a much smaller impact on the behavior of this species than on Green-winged and Scarlet Macaws. It is intriguing to think that, hand-raising may be a viable release strategy for this species, even in areas close to human populations, but a controlled study would be needed before this conclusion can be drawn.
The one drawback of the hand-raising techniques is that the Scarlet and Green-winged Macaws have remained relatively imprinted and have no fear of humans. As a result, this technique would not work well for studies close to populated areas. The current work at Tambopata Research Center is developing supplemental feeding techniques to help these younger chicks survive without them becoming imprinted on humans.
If you would like to visit the Tambopata Research Center on a trip designed especially for parrot lovers and see first hand the research that is being conducted please contact Rainforest Expeditions, Mario Corvetto mlcorvetto@aol.com, (919) 401-5598.
Last updated 07/16/2001
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