Assessment of territory quality and its effects on breeding success in a migrant passerine, the Wheatear Oenanthe oenanthe

摘要: This paper examines how a returning migrant assesses the quality of an area as breeding territory before period peak food demand and effective assessment is in terms success. Male Wheatears Oenanthe oenanthe return from Africa to choose territories Breckland eastern England about March, females arriving shortly after males. The supply was predictable: prey densities during (egg-laying chick independence) were strongly correlated with at same sites arrival establishment. Prey also related vegetation structure, averaging highest on short turf. date size not significantly density but implying that birds used indirect clue availability. Neither nor nest spacing appeared affect losses caused by predators. major variations number young fledged (other than predation) nestlings hatched presence second brood. Both early first brood improved first-brood success necessary for Not all which arrived bred enough First-brood hatching negatively pre-breeding availability structure. Thus using habitat quality, some pairs suffered reduced result implies may be able adequately assess directly time critical (nestling period), when relatively abundant, probably must accumulate reserves eggs poor. Food this determine timing ability rear brood, thus have greater effect