Aspects of the breeding biology of the black-tailed godwit (limosa limosa) with particular reference to coloniality and anti-predator defence

Black-tailed Godwits (Limosa limosa),which nest solitarily as well as in colonies on the Ouse Washes, offer an opportunity to assess within one species the relative advantages and disadvantages of colonial nesting. Possible reasons were investigated, with particular reference to defence against predators. Colonies formed for social reasons rather than because suitable habitat was restricted. Neither the foraging requirements of adults nor of chicks could account for colonial nesting. Breeding success, although very low, was highest in the largest colony, that in a smaller colony being similar to that of single pairs. Flooding and predation were the main causes of nest failure. Colony birds benefitted from very effective group defence against avian predators and this was thought to be the main reason for colonial nesting in this species. It is not known why some individuals nested alone or how they faired in terms of nest defence and causes of breeding failure.