Marbled Duck (Marmaronetta angustirostris) Science Article 1
To design methods to mark Marbled Teal Marmaronetta angustirostris, to test these methods in captive conditions and to apply them in field research in Spain. Location: Marked birds were released at El Hondo, Valencian community (eastern Spain) and Donana (south-west Spain). Captive trials were conducted at nearby recovery centres. Methods: Colour and Darvic rings, nasal markers and wing tags were tested in captivity. Various designs of wing (patagial) tags varying in shape, size, nature of the code and attachment methods were also tested. Nasal markers were rejected after most fell off within a month in captivity. The other methods were used to mark birds that were released into El Hondo (following their rescue when they became trapped in an irrigation channel) or Donana. Results: PVC colour rings stuck with superglue often dropped off within months, probably owing to the high temperatures. Especially designed Darvic rings with two digit alphanumeric codes were used, but these were rarely legible in the field. Initially a wider wing tag was used to mark 52 birds released in 1996, after testing with pinioned birds in captivity. It was then discovered that these tags caused feather wear on the opposing wing in full-winged birds, owing to the spinning of the tags during wing flapping. A narrower tag that greatly reduced this problem was developed and it was used to mark 288 birds released in 1997-1999. Observations of marked birds showed that most birds released at El Hondo remained there, although some were observed at Albufera de Valencia and Marjal del Moro. One bird was also recovered from Algeria. No birds released at El Hondo were recorded in Donana, although one bird tagged in Donana was observed at El Hondo. Tagged females in their first and second years were observed with broods, providing the first breeding observations for Marbled Teal of known age in the wild. Conclusions: Wing tags provided much more data than rings, but there were major problems of tag loss, poor visibility and feather wear. They are most appropriate for intensive studies in the first few months after marking, and are not suitable for general use in this threatened species. El Hondo is likely to be the source for the recent expansion of Marbled Teal into Albufera de Valencia, Marjal del Moro and other valencian breeding sites. There is little connectivity between El Hondo and Donana, the two main breeding areas in Spain.
Green, A. J., Fuentes, C., Vazquez, M., Viedma, C. & Ramon, N., Ardeola 51(1), 2004, 191-202