Male incubation in Northern Lapwings: effects on egg temperature and potential benefits to females

Abstract

The Northern Lapwing Vanellus vanellus is a polygynous shorebird where both parents incubate . However, males show great individual variation with respect to incubation constancy, possibly resulting in variable degrees of incubation costs in females. Here, the influence of male incubation on egg temperature at the end of female recesses is examined by using a theoretical model of egg cooling combined with observations of incubation rhythm and ambient temperature. Estimated egg temperatures were higher after male incubation than when the nests were left uncovered, and consequently eggs were warmer on average in nests with higher male attentiveness . I suggest that this results in higher costs of egg re-warming in females that are less helped by their males in incubation . Moreover, ambient temperatures in the period of observations never exceeded 20°C. Still, egg temperatures were significantly higher than the presumed physiological zero temperature (25°C) with male intermittent incubation . However, there was no difference when males were absent during recesses . These results could potentially indicate fitness benefits to female Northern Lapwings, male care influencing length of incubation periods and embryo survival . Such trends could not be detected in this study, though.