The Tambopata Macaw Project: Developing techniques to increase reproductive success of large macaws

Abstract

LIntroduction

Large macaws are among the most spectacular and revered birds in the world. Unfortunately, they are disappearing from many areas of the tropics. For example the Guayaquil subspecies of the Great-green or Buffon's Macaw (Ara ambigua guyaquilensis) is in imminent danger of extinction CK. Berg pers. com.). In Costa Rica, the Great-green Macaw (A. a. ambigua) has been eliminated from 80% of its former range and only an estimated 200 remain (Powell et al. in prep.). In Bolivia the Blue-throated Macaw (Ara glaucogularis) has been reduced to less than 200 individuals (Hess 1999). In addition, all the blue macaws, Glaucus, Lear's, Hyacinth, and Spix's, are either extinct or gravely endangered (Collar 1997, Juniper and Parr 1998). As a result, there is an urgent need to aid the recovery of macaw populations. The work described here uses three species of large macaws in Peru as a model system to develop techniques that can be used to help the recovery of other macaw species throughout the New World tropics.

The threats that face macaws are many and include habitat loss, hunting, and collecting for the pet trade. Habitat loss takes many forms including clearing for agriculture, cattle ranching and logging. Agriculture, ranching and the subsequent human settlement eliminates the majority of the vegetation but in some instances may leave sufficient food resources to support populations at least over the short term. Tropical logging operations are usually very selective, targeting first the largest examples of marketable trees. This leaves a large amount of vegetation standing including many possible food trees. Macaws are dependent on large, pre-existing tree cavities for nesting. In many instances the nest trees they use may be hundreds of years old and even in virgin forests the lack of suitable nest trees limits the number of macaws that can breed each year (Munn et al., 1991). Logging operations that target these large trees do insidious damage to macaw populations. The forests may look healthy and still have relatively large numbers of macaws, but without suitablenesting sites, the macaw population is doomed to extinction.

Collection for the pet trade is a major threat to nearly all populations of large macaws (Juniper and Parr 1998). Collection techniques are varied and can target either adults or chicks. Adults are captured in a variety of ways either for food, feathers, or to be sold as pets. Snares are placed on suitable perches. In Ecuador collectors set fires at the bases of nests and the smoke is used to knock out or kill the adults (J. Socola pers. com.). In some cases adults are shot in the wing while flying and collected alive. The collection of young for sale is more common than the collection of adults. This is due mostly to the higher demand for young because they make better pets. The number of macaws taken from the wild can be considerable. At this point it is thought that there are more Bluethroated Macaws in captivity than in the wild, and rumors exist of a single shipment of nearly 200 of these macaws. If this is true, this one shipment alone contained more birds than the current wild population.

When young are collected they are taken from nests in a variety of ways. Collectors often free-climb or use a combination of ropes and ladders to get to the nest holes and remove the young. When the collectors cannot gain access to the nests they often cut the entire tree to remove the young. The fall results in the death of up to 60% of the chicks (Gonzalez 1999). Collection for the pet trade is blamed for the disappearance of large macaws from many areas. This direct damage is compounded by the cutting of nest trees by collectors, the natural scarcity of suitable trees, and further removal of large trees by logging operations. These forces have combined to leave the macaws that do remain with few opportunities to nest. As a result, it is clear that just declaring new protected areas may be insufficient to allow macaw populations to recover from the decades of collection and tree cutting.

Previous research in southeastern Peru has shown that macaw reproductive rates in undisturbed areas are extremely low. This is due to three main factors: 1) suitable nesting cavities occur at a density of only one per 15 - 20 ha, 2) only about 60% of nests fledge young as predators and parasites combine to kill many chicks, and 3) successful nests usually fledge only one young even when 3 or 4 eggs are laid and the other chicks die of malnutrition (Munn et al., 1991, Nycander et al., 1995). As a result, a population of 200 macaws may produce as few as eight young per year.

From 1989 - 1993 work was conducted at Tambopata Research Center, Peru to develop techniques to increase the reproductive rates of wild macaws (Nycander et al., 1995). During this 4-year study researchers 1) developed techniques to use live palm trees to create nest sites for Blue-andgold Macaws, 2) constructed artificial nest boxes for use by Scarlet Macaws, and 3) rescued, hand-raised and released Blue-and-gold, Scarlet, and Green-winged Macaw chicks. All of these resulted in great increases in the reproductive output of these three species in the area surrounding Tambopata Research Center.

The current project is· a continuation of the 1989 stu~y. The goal of the current project is to document...

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References

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