Long-term patterns in egg mortality during incubation and chick mortality during rearing in three species of tits in an English woodland

Capsule Mortality from egg-laying to fledging is species-dependent with Great Tits exhibiting greater losses of chicks, Coal Tits greater losses of eggs and Blue Tits exhibiting comparable rates of mortality of eggs and chicks. Aims To determine whether reproductive losses during incubation and chick-rearing were different and to ascertain whether there were different effects in three closely related songbirds. Methods Breeding success of Great Tits Parus major, Blue Tits Cyanistes caeruleus and Coal Tits Periparus ater at Treswell Wood, Nottinghamshire, England was examined, selecting only those nests which fledged at least one chick. Mortality during incubation (i.e. loss of eggs) or rearing (i.e. loss of chicks) was recorded per nest and annual means were calculated and used in the analysis, which examined relationships between year, first-egg date and species. Key factor analysis was used to investigate the relative effects of egg or chick losses on the total breeding mortality. Results Timing of repr...