Sperm Competition and Copulation Intervals of the White Spoonbill (Platalea leucorodia, Aves, Threskiornithidae)


Estación Biológica de Doñana. E-41013 Sevilla


Some aspects of sperm competition were studied in the white spoonbill (Platalea leucorodia) breeding in Doñana National Park (SW Spain). Shorter pair copulation intervals occurred during the prelaying period, when females were subjected to a relatively high frequency of extra-pair copulations. Pair copulation intervals with an intermediate extra-pair copulation by the male mate were longer than those without extra-pair copulation. This result indicates that males need a time of recovery between copulations before they can perform another. Extra-pair copulations by the females did not affect the length of intervals between pair copulations. There were no differences between the lengths of the intervals between an extra-pair copulation by the female and the following pair copulation for cases in which the male mate detected an intruder male attempting copulation with his mate and those in which the intruder remained undetected. However, the correlations obtained between copulatory intervals for detected and undetected cases suggest a copulatory response by their mates, although affected by the required recovery time between copulations by the males. Finally, since extra-pair copulations mainly occurred while male mates were collecting nest material, they engaged in this activity shortly after pair copulations, probably to avoid a last-male advantage under the sperm competition pressure.