Although the poaching of nestlings for the pet trade is thought to contribute to the decline of many species of parrots, its effects have been poorly demonstrated. We calculated rates of mortality due to nest poaching in 23 studies of Neotropical parrots, representing 4024 nesting attempts in 21 species and 14 countries. We also examined how poaching rates vary with geographic region, presence of active protection programs, conservation status and economic value of a species, and passage of the U.S. Wild Bird Conservation Act. The average poaching rate across all studies was 30% of all nests observed. Thirteen studies reported poaching rates of ≥20%, and four reported rates openface> 70%. Only six studies documented no nest poaching. Of these, four were conducted on islands in the Caribbean region, which had significantly lower poaching rates than the mainland Neotropics. The other two studies that showed no poaching were conducted on the two species with the lowest economic value in our sample ( U.S. retail price). In four studies that allowed direct comparison between poaching at sites with active nest protection versus that at unprotected sites, poaching rates were significantly lower at protected sites, suggesting that active protection efforts can be effective in reducing nest poaching. In those studies conducted both before and after the passage of the U.S. Wild Bird Conservation Act, poaching rates were found to be significantly lower following its enactment than in the period before. This result supports the hypothesis that the legal and illegal parrot trades are positively related, rather than inversely related as has been suggested by avicultural interests. Overall, our study indicates that poaching of parrot nestlings for economic gain is a widespread and biologically significant source of nest mortality in Neotropical parrots.

SummaryOrnithologists have hypothesized that some tropical forest birds avoid snake predation by nesting in isolated trees that do not have vines and canopy contact with neighbouring trees. Here we review two complementary studies that support this hypothesis by demonstrating (1) that an abundance of vines and an interlocking canopy characterized Jamaican Black-billed Parrot Amazona agilis nest-trees that failed due to chick loss, presumably to snakes, and (2) that such trees were used preferentially by an arboreal snake congeneric to the snake implicated in the parrot losses. Evidence strongly suggested that losses of nestling Black-billed Parrots were due in substantial part to predation by the Jamaican (yellow) Boa Epicrates subflavus (Boidae). Studies of the closely related Epicrates inornatus on Puerto Rico revealed that trees used by boas had more vine cover and more crown or canopy contact with neighbouring trees than did randomly selected trees. Moreover, the boas had relatively large home ranges and were most active during March to July, which corresponds with the breeding season of parrots as well as other bird species. We suggest that nest failure due to snakes may be reduced in endangered bird species through isolating the nest-tree by eliminating vines and canopy contact with neighbouring trees and shrubs and by placing barriers on the nest-tree trunk.

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We studied productivity and nesting success of the Thick-billed Parrot (Rhynchopsitta pachyrhyncha) during a 7-year period (1995–2001) in five nesting areas at the Sierra Madre Occidental in Mexico. Two breeding areas continue to be the breeding strongholds for the species. We found 553 cavities with associated pairs and determined the outcome of 187 accessible nests. Of 510 eggs followed, 405 (79%) hatched, and 307 (60%) produced fledglings. Clutch size averaged 2.7 eggs, and mean reproductive output was 1.6 fledglings per egg-laying pair. Overall nest success was 80% and ranged from 88% in 1996 to 60% in 2000. This was higher than nest success of most psittacines, and we consider productivity excellent in remaining areas of good habitat. Nevertheless, the species has nearly disappeared from many areas of its former range that have been converted from old-growth coniferous stands to immature stands deficient in both nest sites and food. Productividad y Éxito de Anidación de Rhynchopsitta pachyrhyncha Resumen. Estudiamos productividad y éxito de anidación de Rhynchopsitta pachyrhyncha a lo largo de un periodo de siete años (1995 a 2001) en cinco áreas de anidación en la Sierra Madre Occidental en México. Corroboramos que las dos principales áreas de anidación reportadas en la literatura continúan siendo bastiones para la viabilidad de la especie. Encontramos 553 cavidades con parejas activas y evaluamos el desempeño reproductivo en 187 nidos accesibles. De 510 huevos considerados, 405 eclosionaron (79%), y 307 produjeron volantones (60%). Registramos 2.7 huevos por nidada y un desempeño reproductivo de 1.6 volantones por nidada. El éxito general de anidación fue del 80% y varió entre 88% en 1996 y 60% en el 2000. Comparados con cifras para otros psitácidos, los datos indican niveles altos de productividad para las áreas de anidación estudiadas. Sin embargo, la especie ha desaparecido de gran parte de su rango histórico, donde la actividad de extracción forestal ha transformado el bosque maduro de coníferas en rodales inmaduros con escasos sitios para anidación y reducida disponibilidad de alimento.