A study of seabird feathers has revealed how climate change is shifting the food web in the Indian Ocean.

Alexander Bond at the University of Saskatchewan in Saskatoon, Canada, and Jennifer Lavers at the University of Tasmania in Hobart, Australia, inferred the diets of flesh-footed shearwaters (Puffinus carneipes) by looking at ratios of carbon and nitrogen isotopes in the birds' feathers that were collected between 1936 and 2011.

The duo found that levels of heavy isotopes — which are present at higher concentrations in species further up the food chain — fell in shearwater feathers over the years, hinting that the birds are eating animals that are lower on the food chain. This could be due to a lack of large fish caused by fishing. Furthermore, the length of the shearwaters' food chain could be shortening because of reduced nutrient flow to the Indian Ocean, owing to a warming climate that is weakening the Leeuwin Current near the western coast of Australia.

Glob. Change Biol. http://doi.org/rrp (2014)