Weight loss of the female during the first brood as a factor influencing second brood initiation in Great Tits Parus major and Blue Tits P. caeruleus

Authors

  • JENNY F. DE LAET,

    1. Laboratorium voor Oecologie der Dieren, University of Ghent, Ledeganckstraat 35, B-9000 Ghent, Belgium and Department of Biology, University of Antwerp, U.I.A., B-2610 Wilrijk, Belgium
    Search for more papers by this author
  • ANDRÉ A. DHONDT

    1. Laboratorium voor Oecologie der Dieren, University of Ghent, Ledeganckstraat 35, B-9000 Ghent, Belgium and Department of Biology, University of Antwerp, U.I.A., B-2610 Wilrijk, Belgium
    Search for more papers by this author

Abstract

We tested the hypothesis that the weight lost by female Great and Blue Tits Parus major and P. caeruleus while raising their first brood influences their ability to start a second brood. The evening weight of female parents was recorded when the nestlings were 5 and 13 days old, in different years and habitats. Several predictions were tested: (1) both species lose weight while raising nestlings and Great Tit females which start a second brood lose less weight than females which do not; (2) differences in the average weight lost between years and areas correlate with differences in the proportion of second broods; (3) the relative weight loss in Blue Tits, which only rarely undertake second broods, is higher than in Great Tits in which second broods are more common. Other factors also are related to the probability of undertaking a second brood: more second broods are undertaken by more successful females, adult females and females that lay earlier.

The comparison of Great and Blue Tits suggests that the two species use different reproductive strategies.

Ancillary