Tracking data and retrospective analyses of diet reveal the consequences of loss of marine subsidies for an obligate scavenger, the Andean condor

LAMBERTUCCI, S.A.; NAVARRO, J; SÁNCHEZ ZAPATA, J. A.; HOBSON, K; ALARCON P; WIEMEYER, G.M.; BLANCO, G.; DONÁZAR, J. A.

PROCEEDINGS OF THE ROYAL SOCIETY OF LONDON. SERIES B: BIOLOGICAL SCIENCES.

ROYAL SOC

Lugar: Londres; Año: 2018 vol. 285 p. 1 - 7

0962-8452

Over the last century, marine mammals have been dramatically reduced in the world?s oceans. We examined evidence that this change caused dietary and foraging pattern shifts of the Andean condor (Vultur gryphus) in Patagonia. We hypothesized that, after the decrease in marine mammals and the increase in human use of coastlines, condor diet changed to a more terrestrial diet which, in turn, influenced their foraging patterns. We evaluated the diet by means of stable isotope analysis (δ13C, δ15N and δ34S) of current (last decade) and historical (1841-1933) feathers. We further evaluated the movement patterns of 23 condors using satellite tracking of individuals. Condors reduced their use of marine-derived prey in recent compared to historical times from 33±13% to less than 8±3% respectively, however, they still breed close to the coast. The average distance between the coast and nests was 62.5 km. Some nests were located close to the sea, but some birds forage up to 86k m from nesting sites and must cross over the mountain range to find food. The worldwide reduction in marine mammal carcasses, especially whales, may have major consequences on the foraging ecology of scavengers as well as on the flux of marine inputs within terrestrial ecosystems.