The Darker The Egg, The Better The Dad

New Scientist ^ | 11-12-2007 | Roxanne Khamsi

[blam]

The darker the egg, the better the dad

15:50 12 November 2007
NewScientist.com news service
Roxanne Khamsi

Male spotless starlings seem to be better dads when eggs are dark (Image: Carlos Navarro)

Females in poorer condition tend to lay light coloured eggs (Image: Carlos Navarro)

In a dark twist to parenting, it appears male spotless starlings make better dads if the eggs their mate lays look healthier.

Male spotless starlings tend to feed offspring that hatch from darker blue eggs twice as frequently as those that hatch from pale eggs, a new study shows.

Scientists had wondered why some birds lay flamboyantly coloured eggs, while others lay paler ones. Now researchers suggest that, in spotless starlings at least, males use the intensity of pigment in the eggs as an indication of their mate's health, since females in poor condition tend to lay light coloured eggs.

They say their discovery is significant because it is a case of sexual ornamentation in female birds – when normally males are the ones that get to show off, for example with flashy plumage. And also because it provides a rare example of sexual selection based on a signal of female fitness after the pair have mated.

"The interesting thing is that it's not the female sending the signal – it's the egg," says David Westneat, a researcher at the University of Kentucky in Lexington, Kentucky, US, who was not involved in the research. He adds that it may represent the first example of male birds altering their parental investment according to an indirect signal from their offspring.

Reduced fitness

In the new study, José Javier Cuervo at a Spanish National Research Council unit in Almería, Spain,

[Deguello]

You have to wonder the point of the study until you understand it involves José Cuervo...then you still wonder.

[VirginiaConstitutionalist]

So animals focus their efforts on raising their healthiest young? Wow. I hope lots of tax money went towards proving that.

[Sacajaweau]

This study will certainly solve all the world’s problems. It’s totally worthless. There is no “object” for the study and the numbers it’s based on are too few.