Polar bears make little use of terrestrial food webs: evidence from stable-carbon isotope analysis

  title={Polar bears make little use of terrestrial food webs: evidence from stable-carbon isotope analysis},
  author={Malcolm A. Ramsay and Keith A. Hobson},
SummaryThe mean stable-carbon isotope ratios (δ13C) for polar bear (Ursus maritimus) tissues (bone collagen −15.7‰, muscle −17.7‰, fat −24.7‰) were close to those of the same tissues from ringed seals (Phoca hispida) (−16.2‰, −18.1‰, and −26.1‰, respectively), which feed exclusively from the marine food chain. The δ13C values for 4 species of fruits to which polar bears have access when on land in summer ranged from −27.8 to −26.2‰, typical of terrestrial plants in the Arctic. An animal's δ13C… 
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