Great Tit Parus major survival and the beech-crop cycle.

作者: A.C. Perdeck , M.E. Visser , J.H. Van Balen

DOI:

关键词: JuvenileCropPopulationEcologyBiologyParusAvian clutch sizeZoologySeasonal breederFledgeBeech

摘要: The single most important environmental variable correlating with annual survival of both juvenile and adult Great Tits Parus major is the beech crop index (BCI). This a measure for amount seeds beeches present in winter, correlates size several other tree species. Two, not mutually exclusive, hypotheses exist to explain correlation between BCI survival. first that directly affects (winter-food limitation hypothesis). To test this hypothesis we re-analysed supplemental food experiment Van Balen (1980), extended three more years previously unpublished data. We found increased juveniles adults, mainly low years, confirming winter-food hypothesis. second states winters high are preceded by springs densities caterpillars (the breeding-season Using data long term studies Dutch Tit populations show does hold because (1) caterpillar densities, (2) mean fledging mass increasing but no effect on parental was found, (3) affected mass, nor their during chick rearing. Finally that, despite fact level probably can be predicted at time breeding season BCI, reproductive decisions (clutch size, laying date percentage broods) levels following winter. [KEYWORDS: major; limitation; provisioning; population dynamics; Winter; population; food; fluctuations; density]

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