Size and spatio-temporal variations of the largest known Andean condor population: communal roosts and conservation

LAMBERTUCCI, S. A.

San Carlos de Bariloche, Argentina

Congreso; VI Southern Connection Congress; 2010

Universidad Nacional del Comahue

Estimations of population sizes of endangered species are fundamental for conservation. The current estimate of the global Andean condor Vultur gryphus population comes from limited local scale counts. Simultaneous censuses on 10 condor communal roosts were conducted (between 2006-2008) in northwest Patagonia, Argentina, to obtain a minimum population number, to estimate the size of the local population, and to describe bird use of the roosts by season and age classes. I fitted the data to two asymptotic models to calculate the population of condors as a function of the number of communal roosts surveyed. In an area of approximately 6300km2 I obtained a minimum population size of 246 individuals by direct observation, and a population estimate of 296 condors (range 260-332) by applying the models. This value represented the largest population known for this species, comprising 68.5% adults and 31.5% immatures. Condors had large aggregations in some communal roosts and used the study area with a clear seasonality, increasing from autumn to spring and decreasing in summer. Long-term monitoring of communal roosts along the Andean condor’s distribution can be useful for the detection of potential declines of this rare and vulnerable species.