South-west France (argenteus - Herring Gull)

The argenteus, in south-west France, appear to be basically similar to those found further north, in say Roscoff. The adults have flesh legs and typical argenteus calls and behave like Herring Gulls in all respects. The juveniles have dusky heads, uncontrasting mantles, obvious pale primary windows and only one bar on the inner wing as expected for argenteus. However, unexpected features are that the juveniles usually show a gleaming white tail and an almost entirely black bill as in Dark Atlantic Yellow-legged Gull. In mid-August (11th), many adults show a moult condition similar to those in Santander with P5 growing and P6 missing and with slightly speckled white heads with denser markings around the eye. The argenteus this far south occupy a colony on Fort Boyard which was discovered in 1974 and is thought to be occupied by birds moving in from the north (Nicolau-Guillaumet, 1977).