Alaska in two waves; local breeders in early May, and larger flocks in the third week of May en route to breeding grounds further north. Behaviour and ecology Breeding The bar-tailed godwit is a non-breeding migrant in Australia and New Zealand. Birds first depart for their northern hemisphere breeding sites at age 2–4. Breeding take place each year in Scandinavia, northern Asia, and Alaska. The nest is a shallow cup in moss sometimes lined with vegetation. Clutch size is from 2 to 5, averaging four. Both sexes share incubation of the eggs for 20 to 21 days, the female during the day and the male at night. Food and feeding The birds' main source of food in wetlands is bristle-worms (up to 70%), supplemented by small bivalves and crustaceans. In wet pastures, bar-tailed godwits eat invertebrates. In a major staging site in the northern Yellow Sea, they continue to hunt polychaetes, but most of their food intake is the bivalve mollusc Potamocorbula laevis, which they generally swallow whole. Male bar-tailed godwits are smaller than females and have shorter bills. In a study at the Manawatū Estuary, shorter-billed birds (males) fed mostly on small surface prey like Potamopyrgus snails, half being snail specialists, whereas females consumed more deeply-buried prey such as worms; the birds also displayed some individual food preferences. Status The status of the bar-tailed godwit is Near Threatened, and the population is declining. Fewer birds have been using East African estuaries since 1979, and there has been a steady decline in numbers around the Kola Peninsula, Siberia, since 1930. The global population is estimated to number 1,099,000–1,149,000 individuals. Both L. l. bauri and L. l. menzbieri adult survival rates decreased between 2005 and 2012, probably because of the loss of intertidal staging areas in the Yellow Sea. The construction of seawalls and the reclamation of mudflats have led to a critical reduction in food supplies for migrating birds, particularly subspecies like L. l. menzbieri that rely on the Yalu Jiang estuary on both their northward and southward migrations. Numbers of L. l. baueri have declined in New Zealand from over 100,000 in the late 1980s to 67,500 in 2018. The bar-tailed godwit is one of the species to which the Agreement on the Conservation of African-Eurasian Migratory Waterbirds (AEWA) applies. In New Zealand the species is protected under the 1953 Wildlife Act. Gallery References Identification External links Bar-tailed godwit