IS THE EXPRESSION OF MALE TRAITS FEMALE LESSER KESTRELS RELATED TO SEXUAL SELECTION

Some lesser kestrel females (Falco naumanm) show male plumage traits, i.e. grey rumps and tails. This phenomenon has seldom been analyzed in birds, and two hypotheses have been suggested to explain it. The firs t proposes that, when sexual selection acts favouring the expression o f a trait males, females could show the analogous character by genetic correlation (indirect sexual selection). Alternatively, the expressio n of these traits in females could be favoured by intra-sexual competi tion or even by male mate choice selecting ornamented females (direct sexual selection). We have tested if female with male traits we favour ed Lp direct sexual selection, through a 3-yr observational study of 2 39 female lesser kestrels. Our results cannot support the predictions, as females with grey plumages do not achieve access to better breedin g opportunities or fitness benefits. These traits do not seem to be ho nest signals of phenotypic quality, since physical condition and survi val did not differ between females which showed male traits and those which did not. The expression of male traits in these females increase d with their ages, but showing a high individual variability. Finally, since the genetic correlation hypothesis is unlikely in this species because all males have grey rumps and tails, we propose a new age-rela ted hormonal explanation.