Thursday, 31 May 2012

Franklin's gull

Larus pipixcan

Photo by Alan Vernon (Wikipedia)

Common name:
Franklin's gull (en); gaivota-de-Franklin (pt); mouette de Franklin (fr); gaviota de Franklin (es); präriemöwe (de)

Order Charadriiformes
Family Laridae

This species breeds in central North America, mostly in Alberta, Saskatchewan and Manitoba, Canada; and in Montana, North Dakota and South Dakota, United States. They migrate south to winter along the Pacific coast of South America, from Ecuador to Chile and further inland in northern Argentina.

These birds are 32-38 cm long and have a wingspan of 85-95 cm. They weigh 220-335 g.

The Franklin's gull breeds in marshes and inland lakes with emergent vegetation. Outside the breeding season they are found in coastal areas, lakes, marshes, cultivated fields and rubbish dumps.

During the breeding season they mostly eat earthworms, chironomids and other aquatic insects, grasshoppers and sometimes also rodents and seeds. Outside the breeding season their diet includes a larger portion of fish, but also insects and other invertebrates, seeds and often also offal and refuse.

Franklin's gulls breed in May-August. They are highly gregarious, forming colonies of hundreads to over 10.000 pairs. The nest is a floating platform of vegetation, placed in thick reeds above water. The female lays 2-4 creamy-white, yellowish or greenish eggs with dark brown spots. The eggs are incubated by both parents for 23-26 days. The chicks are semi-precocial, but remain in the nest for around 3 weeks and receive food from both parents until fledging, 31-35 days after hatching.

IUCN status - LC (Least Concern)
This species has a very large breeding range and the global population is estimated at 470.000-1.500.000 individuals. The population has undergone a small increase over the last 4 decades.

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