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.
In this investigation, we use variation in wing morphology, echolocation behaviour, patterns of habitat use and molecular diet analysis to demonstrate that six species of sympatric insectivorous bats in Jamaica show significant differences that could explain resource partitioning among the species. High-intensity echolocating species that used shorter, broadband signals and had shorter, broader wings (Pteronotus macleayii, Pteronotus quadridens, Mormoops blainvillii) foraged most in edge habitats, but differed in timing of peak activity. P. macleayii and M. blainvillii differed in diet, but low sample size precluded diet analysis for P. quadridens. High-intensity echolocating species that used longer, more narrowband signals and had longer, narrower wings (Molossus molossus, Tadarida brasiliensis) foraged most in open areas and differed in diet from the other species. Two disparate species were most active in clutter (dense vegetation). Pteronotus parnellii used high-duty-cycle echolocation apparently specialized for detecting fluttering targets in clutter. Macrotus waterhousii used low-intensity, broadband echolocation calls and presumably uses prey-generated sounds when foraging. These two species also differed in diet. Our data show that differences in morphology and echolocation behaviour coincide with differences in habitat use and diet, resulting in minimal overlap in resource use among species.
Black-billed Parrot Amazona agilis and Yellow-billed Parrot A. collaria are endemic to Jamaica and are restricted to remnant patches of mid-elevation wet limestone forest. Cockpit Country is the stronghold of Black-billed Parrot and is the only region where these two species occur sympatrically in significant numbers. In northern Cockpit Country, Black-billed Parrots nested commonly in degraded and regenerating edge habitat, where natural nesting cavities did not appear to be limiting. Yellow-billed Parrot nests were less abundant in the study area. Black-billed Parrots produced clutches of 3 or 4 eggs and incubation was approximately 24 days. Nestling growth and development were characteristically slow and the nestling period prolonged. Nesting success of both species was low for non-excavating, cavity-nesting species, but successful nests were prolific. Black-billed Parrot nestling mortality was highest during the first four weeks of the nestling period, the primary cause being predation, followed by “dead-in-nest, possible hypothermia”. Many aspects of Black-billed and Yellow-billed Parrot nesting behaviour may be related to predation. The majority of predation events were attributed to the endemic and Vulnerable yellow boa Epicrates subflavus. Such predator-prey dynamics will challenge Jamaica's natural resource managers to develop a more comprehensive attitude away from single-species conservation towards multiple species and their interactions in a complex habitat.
Abstract:The Caribbean Islands Biodiversity Hotspot is exceptionally important for global biodiversity conservation due to high levels of species endemism and threat. A total of 755 Caribbean plant and vertebrate species are considered globally threatened, making it one of the top Biodiversity Hotspots in terms of threat levels. In 2009, Key Biodiversity Areas (KBAs) were identified for the Caribbean Islands through a regionallevel analysis of accessible data and literature, followed by extensive national-level stakeholder consultation. By applying the Vulnerability criterion, a total of 284 Key Biodiversity Areas were defined and mapped as holding 409 (54%) of the region's threatened species. Of these, 144 (or 51%) overlapped partially or completely with protected areas. Cockpit Country, followed by Litchfield Mountain -Matheson's Run, Blue Mountains (all Jamaica) and Massif de la Hotte (Haiti) were found to support exceptionally high numbers of globally threatened taxa, with more than 40 such species at each site. Key Biodiversity Areas, building from Important Bird Areas, provide a valuable framework against which to review the adequacy of existing national protectedarea systems and also to prioritize which species and sites require the most urgent conservation attention.
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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