Abstract To determine whether stable isotope measure-ments of bird feathers can be used to identify moulting (interbreeding) foraging areas of adult seabirds, we ex-amined the stable-carbon ( d 13C) and nitrogen ( d 15N) iso-topic composition of feathers of chicks and adults of black-browed albatros...
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| Format: | Text |
| Language: | English |
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| Online Access: | http://citeseerx.ist.psu.edu/viewdoc/summary?doi=10.1.1.476.8280 http://www.cebc.cnrs.fr/publipdf/2000/COec122.pdf |
| Summary: | Abstract To determine whether stable isotope measure-ments of bird feathers can be used to identify moulting (interbreeding) foraging areas of adult seabirds, we ex-amined the stable-carbon ( d 13C) and nitrogen ( d 15N) iso-topic composition of feathers of chicks and adults of black-browed albatrosses (Diomedea melanophrys) from Kerguelen Islands, southern Indian Ocean. Albatross chicks are fed primarily fish (75 % by mass), the diet be-ing dominated by various species of the family Noto-theniidae and Channichthyidae which commonly occur in the shelf waters in the vicinity of the colony. d 13C and d 15N values in chick feathers, which are grown in sum-mer in the breeding area, were lower than values in adult feathers, which are grown in winter ( d 13C: –19.6 ‰ ver-sus –17.6 ‰ and d 15N: 12.4 ‰ versus 15.7‰, respective-ly). No differences in d 13C and d 15N values were found in adult wing feathers moulted in 1993 and 1994 and in adult feathers formed at the beginning, middle and end of the 1994 moulting period. These data are consistent with adults moulting in the same area and feeding at the same trophic level from one year to the next and with no major changes in foraging ecology within a given moul-ting season; they suggest that foraging grounds were dif-ferent in summer and winter and that these differed in their stable-isotope signature. Changes in both feather d 13C and d 15N values indicated feeding south of the Sub-tropical Front (STF) during chick rearing, which is in agreement with the known foraging ecology at this time and feeding north of the STF during moult. This, togeth-er with band recoveries from adult birds, indicates that black-browed albatrosses from Kerguelen Islands win-tered in subtropical waters off southern Australia. The stable-isotope markers in feathers, therefore, have the potential for locating moulting areas of migratory sea-bird species moving between isotopically distinct re-gions and for investigating seabirds ’ foraging ecology during the poorly known interbreeding period. ... |
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