Ageing immature Atlantic Yellow-nosed Thalassarche chlororhynchos and Black-browed T. melanophris Albatrosses in wintering grounds using bill colour and moult

• Main Authors: Bugoni, L., Furness, R.W.
• Format: Article in Journal/Newspaper
• Language: unknown
• Published: 2009
• Subjects: QL Zoology; South Georgia Island
• Online Access: https://eprints.gla.ac.uk/43008/; http://www.marineornithology.org/cgi-bin/getpage.cgi?vol=37&no=3

Atlantic Yellow-nosed Thalassarche chlororhynchos and Black-browed T. melanophris Albatrosses were captured at sea off the Brazilian coast and aged based on bill colour and moult of wing, tail and contour feathers. First-year Atlantic Yellow-nosed Albatrosses have a black bill and show no moult. One-year-olds have some yellow at the culminicorn and show tail and contour feather moult, but not primary moult. Two-year-olds show more yellow on the bill, progressing through to full orange culminicorn and reddish nail at age 3, but three-year-olds differ from adults by having only a pale vertical bar at the base of ramicorn and flight feather moult during the breeding period. Adults have a more pronounced vertical bar at the base of the ramicorn and do not moult flight feathers while breeding. Comparison with previous descriptions for ageing Black-browed Albatross shows that birds off Brazil (originating mainly from the Falkland Islands/Malvinas) differ considerably from birds from South Georgia Island. First-year birds wintering off southern Brazil show paler bills, with colour changing quickly after fledging. However, Black-browed Albatrosses two years old with fully black bills, as those described from South Georgia, were also sampled, suggesting a variety of origins of Black-browed Albatrosses wintering in the area and inter-colony differences in bill colour maturation.