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

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.