A population viability analysis (PVA) for Eastern Sarus Crane, Grus antigone sharpii

The Sarus Crane Grus antigone (Linnaeus, 1758), a wetland bird species in South East Asia and Northern Australia, is currently listed as a globally vulnerable species. A subspecies of this bird, the Eastern Sarus Crane G. a. sharpii is distributed in the lower Mekong basin, South East Asia and is considered endangered due to its small population size, about 500-1000 individuals, inappropriate reserve management, and the intense development pressures in the region. A population viability analysis (PVA) of the birds may help managers to comprehend the processes governing the population dynamics and then highlight needs for future conservation, management, and research activities. Part 1 of this paper provides requisite data for the Eastern Sarus Cranes' PVA, including estimates of population abundance, survival and fecundity rates, and the carrying capacity of the area supporting the population. These data were obtained from fieldwork between the years 2001 and 2004 by the author and from a review of the literature. Part 2 is the description and simulations of the PVA models. Three stage-based demographic models of the population were run in RAMAS/Metapop 4.0 (Akcakaya 2002) to understand structural sensitivities of the models. Different scenarios were then run on the complete model to investigate the effects that each of them has on the model outcomes. The compiled data were also parameterised and simulated in VORTEX 9.5 (Lacy et al. 2005) to compare the risk estimates made by the two modelling packages. Part 3 involves discussions and conclusions of the results from the PVA models and proposals of management and conservation actions for the population. Although habitat loss has been considered the most threatening process to the population, the models were particularly sensitive to changes of poaching activities on the population. It is therefore suggested that improved population management is the most cost-effective option for the conservation of the endangered subspecies in the near future