Variation in Belcher's Gulls

at Paracas and Ballestas Islands, Peru

Adult Belcher's Gull in summer (alternate) plumage. Ballestas Islands near Paracas, Peru, on 31 October 2013. Belcher's Gulls breed mostly from October to March, though some may breed all year round. This gull is endemic to western South America (Howell and Dunn 2007). All adults I saw were in summer plumage: clean white heads, bright yellow legs, large bright red mark on the tip of the bill and smaller subterminal black mark. In all plumages Belcher's Gulls have a dark eye.

First cycle Belcher's Gull (left) and two adults in summer plumage (right) on the Ballestas Islands,  on 31 October 2013

Adult Belcher's Gull in summer plumage on the beach at the Hotel Doubletree Paracas on 31 October 2013. Our hotel was great for watching gulls.

Adult Belcher's Gull in summer plumage showing well-defined tail band and broad white trailing edge to the secondaries. Ballestas Islands on 31 October 2013.

First cycle Belcher's Gull in mostly worn juvenal plumage. Paracas, Peru, on 31 October 2013.  First year birds showed much plumage variation.

First cycle Belcher's Gull at Paracas on 31 October 2013.

First cycle Belcher's Gull at Paracas on 31.October 2013.

First cycle Belcher's Gull on the Ballestas Islands. 31 October 2013.

First cycle Belcher's Gull at Paracas on 1 November 2013

Second summer Belcher's Gull at Paracas. 31 October 2013.

Second summer Belcher's Gull. Paracas on 31 October 2013.