Breeding dispersal of Great Tits Parus major in a homogeneous habitat: effects of sex, age, and mating status

摘要

We studied patterns of breeding dispersal of adult Great Tits Parus major in a homogeneous habitat (extensive orange plantations) in eastern Spain. Data included 482 movements of known individuals gathered during 11 years. Most birds (67%) did not change territory between seasons. Dispersal propensity was independent of sex, and decreased with age at least up to the sixth year of life. Of birds that changed territory, 92% moved less than 200 m. Young females dispersed significantly farther than adult males, while values for young males and adult females were intermediate. About two thirds of the birds kept the same mate in consecutive years. Both males and females that changed mate dispersed more often than faithful individuals, and females, but not males, dispersed also farther after mate change. Most individuals changed mate because of the death of their partner. The probability of dispersal was similar for widows and divorcees of either sex. However, distances moved by widowed females were longer than those of widowed males or divorced males or females. We discuss these results within the context of breeding dispersal in passerines. Results generally agree with the ideas that (1) females disperse more than males; (2) dispersal tendency decreases with age; and (3) dispersal is more frequent after mate change. However, the interactions among sex, age and mating status, as well as characteristics of the habitat, modulate these general trends, so that dispersal patterns could vary both within and between populations of the same species.