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USGS · 70028266

Estimation of density and population size and recommendations for monitoring trends of Bahama parrots on Great Abaco and Great Inagua

F. F. Rivera-Milan·J.A. Collazo·C. Stahala·W. J. Moore·A. Davis·G. Herring·M. Steinkamp·R. Pagliaro·J.L. Thompson·W. Bracey
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Abstract

Once abundant and widely distributed, the Bahama parrot (Amazona leucocephala bahamensis) currently inhabits only the Great Abaco and Great lnagua Islands of the Bahamas. In January 2003 and May 2002-2004, we conducted point-transect surveys (a type of distance sampling) to estimate density and population size and make recommendations for monitoring trends. Density ranged from 0.061 (SE = 0.013) to 0.085 (SE = 0.018) parrots/ha and population size ranged from 1,600 (SE = 354) to 2,386 (SE = 508) parrots when extrapolated to the 26,154 ha and 28,162 ha covered by surveys on Abaco in May 2002 and 2003, respectively. Density was 0.183 (SE = 0.049) and 0.153 (SE = 0.042) parrots/ha and population size was 5,344 (SE = 1,431) and 4,450 (SE = 1,435) parrots when extrapolated to the 29,174 ha covered by surveys on Inagua in May 2003 and 2004, respectively. Because parrot distribution was clumped, we would need to survey 213-882 points on Abaco and 258-1,659 points on Inagua to obtain a CV of 10-20% for estimated density. Cluster size and its variability and clumping increased in wintertime, making surveys imprecise and cost-ineffective. Surveys were reasonably precise and cost-effective in springtime, and we recommend conducting them when parrots are pairing and selecting nesting sites. Survey data should be collected yearly as part of an integrated monitoring strategy to estimate density and other key demographic parameters and improve our understanding of the ecological dynamics of these geographically isolated parrot populations at risk of extinction.

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F. F. Rivera-Milan, J.A. Collazo, C. Stahala, W. J. Moore, A. Davis, G. Herring, M. Steinkamp, R. Pagliaro, J.L. Thompson, W. Bracey. 2005. Estimation of density and population size and recommendations for monitoring trends of Bahama parrots on Great Abaco and Great Inagua. https://doi.org/10.2193/0091-7648(2005)33%5B823%3Aeodaps%5D2.0.co%3B2

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