Brooding female birds respond to vivid male plumes

LONDON - Male birds displaying gorgeous plumes seem to positively affect brooding females of the same species, improving offspring growth.

Scientists made the discovery during a breeding experiment with Houbara bustards, a North African bird species with a very distinctive courtship behaviour.

Females observing such colourful males showing off in the experiment were more fertile and had a greater breeding success due to an increased allocation of testosterone into their eggs, prompting an increase in the growth rate of chicks.

The results showed 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, says Adeline Loyau and Frederic Lacroix, who led the study.

Loyau of the Helmholtz Centre for Environmental Research (UFZ) (Germany) and the French CNRS station for experimental ecology and her colleague Lacroix from Emirates Centre for Wildlife Propagation (ECWP), confronted 90 brooding Houbara bustard females (Chlamydotis undulata undulata) with various individuals of the same species.

In the 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 metres 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.

“To my knowledge our study is the first example in species conservation of a successful manipulation of maternal allocation of resources through sensory stimulation,” explains behavioural biologist Loyau.

“Our results show that it is possible to control maternal allocation of resources independent of the quality of male genes,” said Loyau, according to a UFZ, ECWP release.

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 programmes of other threatened bird species.

The Houbara bustard is a sandy-coloured resident of deserts, with its distribution ranging from North Africa to Mongolia. In the Arab world it is common prey for falcon hunting.

Both hunting and a loss of habitat have diminished Houbara bustard populations and in the meantime the species is classified as vulnerable.

These findings were published in the online edition of Proceedings of the Royal Society B.