Thursday, August 9, 2007

PS 57-35: Multi-scales characterization of roosting places of the king vulture, Sarcoramphus papa, in the Calakmul region

Yol P. M. Reyes and Sophie Calmé. El Colegio de la Frontera Sur, ECOSUR

The king vulture, Sarcoramphus papa, is a species scarcely studied which is considered endangered in Mexico. To know how a species interacts with its environment, it is necessary to consider the different spatial scales influencing its distribution. The main goal of this research is to determine the interaction between roosting sites and the composition and configuration of habitat at different spatial scales, to gain understanding of the variables that are key to the species. I located 12 active and 12 abandoned roosting sites, helped by key local informants. At each site, I recorded the geographical position and measured several characteristics (vegetation type and cover, tree species and architecture, distance to water). In addition, I measured vegetation (type, number and size of forest patches, etc.) and human-related variables (distance to settlement, to fields, etc.) around roosting sites, at five spatial scales (500, 1,000, 2,000, 4,000 and 8,000 m), using a classified satellite image (2000, Landsat 4). To explore the relationships between the presence of roosting sites and the environmental variables at multiple scales, I used multiple and logistic regression and confronted models using Akaike’s Information Criterion. At the local scale I found that roosting sites are large trees that stand out of the canopy, and are close to water (<200 m). At larger scales, these sites are located within large patches of conserved tropical forest. The abandonment of roosting sites was clearly related both to the loss of forest cover at local scale and to the disappearance of the closest water point. The information provided by my study should allow understanding of the process of roosting site selection by king vultures, as well as the factors promoting site abandonment. Both aspects are important to create conservation strategies for this species, which could disappear if habitat lost and fragmentation continues. 

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