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.
Geophagy, the ingestion of soil, has been reported for birds and other animals from many regions, but its functions remain debated. We report geophagy for the first time for New Guinea birds: four or five parrot species, two or three pigeon species, one hornbill species, one crow species and possibly one cassowary species. These species ate soil at an area of bare ground created by a landslide on a steep mountain slope. Parrots visited the site in the early morning, pigeons in the late afternoon, flying in from considerable distances. All 11 of these species are frugivores. In the vicinity, we recorded 133 other bird species (including 37 other frugivore species) that were not observed to visit the site. Within each taxonomic group of frugivores, those practising geophagy tended to be the largest species of their guild. To test hypotheses regarding the functions of geophagy, we carried out chemical and physical analyses of soil samples from the site. The ingested soil was much too fine‐grained to be useful as grit; it contained only modest levels of all 14 minerals analysed; it lacked buffering capacity; and there was no evidence that it protected against diarrhoea. Instead, the soil's high measured cation‐exchange capacity, high content of cation‐binding minerals and binding of large quantities of tannic acid and quinine suggest a different hypothesis: that geophagy in this case served to bind poisonous and/or bitter‐tasting secondary compounds in ingested fruits and seeds. Geophagy thus represents one weapon in the escalating biological warfare between plants and animal consumers‐an evolutionary arms race at which parrots excel. We discuss five unsolved problems posed by geophagy.
Wild parrots represent one of the greatest commercial interests in the legal trade in wild birds. Although it is difficult to quantify, there is a considerable illegal trade in wild parrots. Thirty-six per cent of the world's parrot species are listed by the International Union for the Conservation of Nature as threatened or near threatened, and 55% of these are threatened to some degree by trade. In this paper, we investigate the impact of protection on the number of nests that failed because of nestlings being taken by humans (hereafter nest take) and on nesting success in parrots. We collate data on parrot nest take from published and unpublished studies from Africa, Asia and Australasia, including countries and sites with and without national and local parrot protection measures in place. Nest take was insignificant in Australia, where all studies were from areas with both local and national protection. For less developed countries, levels of nest take were variable between studies, spanning the whole range from 0 to 100%. Protection significantly reduced nest take and correspondingly increased nesting success. Our results corroborate those for the Neotropics; thus, the advantages of protection appear to be independent of geographical location or political and economic conditions. We analysed data on legal trade in wild-caught parrots before and after implementation of the 1992 Wild Bird Conservation Act (which practically eliminated import of parrots to the USA) and found that there was no apparent shift in parrot imports to other global regions from the Neotropics. We suggest that conservation of parrots globally would benefit from similar legislation introduced in other regions, such as the EU (15), which is responsible for more than 60% of global imports of wild parrots.
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