Visual stimulation from attractive males positively affects brooding females

WASHINGTON - Brooding female birds are sensitive to visual stimulation from attractive males of the same species, a breeding experiment with Houbara bustards has led scientists to conclude.

Females that observed highly displaying male birds in the experiment were more fertile and had a greater breeding success due to an increased allocation of testosterone into their eggs, leading to an increase in the growth rate in chicks.

The results demonstrated that using artificial insemination without appropriate stimulation of breeding females probably has negative impacts on their breeding performance and can therefore even affect the survival of a species, according to the researchers.

For the experiment, Adeline Loyau of the Helmholtz Center for Environmental Research (UFZ) and the French CNRS station for experimental ecology and her colleague Frederic Lacroix (ECWP) confronted 90 brooding Houbara bustard females (Chlamydotis undulata undulata) with various individuals of the same species.

In the Emirates Center for Wildlife Propagation (ECWP) in Moroccan Missour, 30 female birds were visually confronted with either highly displaying male birds, poorly displaying male birds, or females.

During the experiment the female birds under investigation were artificially inseminated and kept isolated in aviaries five meters apart from birds of the same species in other aviaries. That way the scientists were able to exclude any other factors from playing a role in the experiment other than that of visual stimulation.

Loyau said: “To my knowledge our study is the first example in species conservation of a successful manipulation of maternal allocation of resources through sensory stimulation. Our results show that it is possible to control maternal allocation of resources independent of the quality of male genes.”

Male display courtship constitutes an effective signal thereby providing conservationists with a simple and inexpensive means. The results could therefore be very significant for the improvement of captive breeding programs of other threatened bird species.

Already in 2007, Adeline Loyau and colleagues found that females of the Blue Peacock (Pavo cristatus) that had mated with attractive males increased the allocation of resources into their eggs compared to females that had mated with unattractive males.

With attractive partners they laid larger eggs and increased the yolk testosterone levels, which has a direct influence on the growth rate of offspring.

The latest study appears in the online edition of Proceedings of the Royal Society B. (ANI)