Depto. de Ecologia Evolutiva, Museo Nacional de Ciencias Naturales (CSIC), Jose Gutierrz Abascal 2, E-28006 Madrid, Spain. Email:MCNS111@fresno.csic.es
Does daylength explain the latitudinal variation in clutch size of Pied Flycatchers Ficedula hypoleuca?
Article first published online: 28 JUN 2008
Volume 141, Issue 1, pages 100–108, January 1999
How to Cite
SANZ, J. J. (1999), Does daylength explain the latitudinal variation in clutch size of Pied Flycatchers Ficedula hypoleuca?. Ibis, 141: 100–108. doi: 10.1111/j.1474-919X.1999.tb04268.x
- Issue published online: 28 JUN 2008
- Article first published online: 28 JUN 2008
- Received 25 July 1997; revisions accepted 22 September 1997
Geographical trends in breeding parameters were studied in the Pied Flycatcher Ficedula hypoleuca in the western Palaearctic. Predictions arising from the hypothesis that daylength and/or energy requirements of the brood explain latitudinal clutch size variation were tested. The nestling period decreased with latitude, but nestling mass on day 13 after hatching did not show a trend with latitude. The length of the daily activity period (working day) at the time of peak brood demand showed a quadratic relationship with latitude and did not increase linearly with daylight hours. The present study supports the hypothesis that latitudinal clutch size variation is influenced by the duration of the working day and the energy requirements of the brood. The balance between the energy requirements of the brood and the parents, in relation to the duration of working day and ambient temperature, are proposed to explain the latitudinal variation in clutch size in the Pied Flycatcher.