Parrots In Peril

Posted on Sat May 17 2008

By: Hilary Feldman in Environment

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Despite concerted efforts, some populations just don’t seem to rebound. That is one problem facing conservation attempts - over and above the usual issues of habitat degradation and other threats that put species on the endangered list. A new study in Ecological Monographs seeks to understand the stalling of otherwise protected populations.

The Puerto Rican parrot is one of the most endangered bird species, with only 30-40 wild individuals. The species has faced many of the same issues as other exotics. Past deforestation eliminated most of the parrot’s habitat, poachers capture birds for sale to pet stores, other birds compete for the remaining scarce resources such as nesting cavities, and hurricanes wreak occasional devastation.

It is the only endemic parrot species in Puerto Rico - and the last surviving parrot in the US. Individuals mature after about 3-5 years, forming long-term pair bonds for nesting and breeding. They feed on palm fruits, especially during the nesting season.

For more than 30 years, conservation efforts have been focused on increasing the population. But to no avail. The parrots have dipped down to as few as 13 individuals, and the average year sees only one new parrot added to the population. The small group is now resident in “El Yunque” (the Caribbean National Forest), along with additional members reared in captive breeding facilities. The hope is to establish a parrot population in a second location. The US Fish and Wildlife Service works in collaboration with other agencies, with the goal of sustaining a total population of 500 parrots in each of the two prospective groups.

Surprisingly, the recent analysis of factors found that, although sporadic, hurricanes were most damaging to parrots. A single major hurricane can decimate the already teetering population. Unfortunately, the prediction is for increased hurricane activity with global warming. The second issue was reduced breeding by adult birds. Despite being of reproductive age, some mature parrots are not forming pairs and reproducing. With the population at a dramatically low level, even a single individual makes a difference. Nest site availability and egg failure played lesser roles in the population’s struggle, as well as inbreeding problems.

Once a population experiences a pronounced bottleneck, many things may suppress further growth. For example, in the past low hatching success and nest predation were major problems for the local parrots. Dedicated efforts by wildlife officials, focused on nest-guarding, improved that particular challenge but other issues have also arisen. Hopefully, the insights gained from factor analysis will help further conservation efforts.

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