science / sex / Uncategorized

It’s for the (male) birds…

annejjacobson4 Comments

Wouldn’t you just know!

Female birds sacrifice health to create more colourful eggs

Published online 2 October 2008 | Nature | doi:10.1038/news.2008.1146

Bright blue eggs keep males keen on fatherhood.

Matt Kaplan

Great artists are said to pour all their energies onto the canvas, leaving them exhausted after a flurry of creativity. Now, researchers have found that female birds make a similar sacrifice when colouring their eggs, creating vivid hues at the expense of their health.

And of course they would have to have blue eggs!

Note:  this presumably is not all birds.

4 thoughts on “It’s for the (male) birds…”

  1. how noble! the angel(s) of the nest?
    and it would have to be blue, because male birds need to be attracted to the color of the sky, in order to fly around and meet more lady birds. or something.
    i kid, but even if this is the best research possible, it’s just like my dad used to say about the warnings on artificial sweetener that says that it causes cancer in lab rats: it just goes to show that it pays not to be a lab rat!

  3. Ok, I am a geeky scientist but I went and read the full report and this is absolutely appalling science and science writing. The headline is so over-dramatic for what was actually found:

    “Morales and colleagues report in Behavioural Ecology and Sociobiology that neither laying intensely blue eggs nor having to rebuild a nest triggered a noticeable decrease in plasma concentrations of the antioxidant. But both factors combined did.”

    So it’s not as simple as the headline states, just laying blue eggs had no effect.

    “The scientists suggest that the birds somehow shift their allocation of biliverdin towards the eggs, depleting their own antioxidant defences in the process. The effect becomes measurable in birds that are already stressed by having to rebuild their nest, something that is itself expected to decrease antioxidant levels.

    “To the best of our knowledge, this is the first evidence that blue eggs are not free — there is a big price that the females are paying,” says Morales.

    “This makes a good case that the blue eggs are affecting the health of the females,” says evolutionary ecologist, Martin Schaefer at the University of Freiburg in Germany.

    Schaefer suggests that the next step is to quantify a direct link between low biliverdin concentrations and the birds’ chances of survival. “Running the study again while monitoring long-term survival of the mothers and their offspring would solidify this,” Schaefer says.”

    And there’s part two of the problem, there was no demonstration of a sacrifice made. There is a change in a chemical concentration that has NOT been correlated with any actual ill effect. Given how poorly biomarkers correlate with diseases, there probably will never be one….

    … but it made a dramatic headline. Grrrrrrr.

    Sigh. I weep for science some days.

  4. michelleloyen, mea culpa!

    I read the article after seeing your comment and what I could find of the original articles. There is for me a pretty big puzzle and that’s the nest removal technique and its role in studying fertility in birds. Apparently the nest removal sent the birds into overdrive and they produced more fledglings than usual. Given the way the PI is responding to comments now showing up in Nature, she seems pretty confident in the way the results are reported, regarding both the connection with laying bright blue eggs and with health costs. If so, then there might be some agreement in the field about what can be learned from moving the nests. Perhaps you can infer what the birds are prepared to do in a more adverse natural setting. And perhaps there’s some agreement that health stress is a plausible result in advance of longitudinal studies??

    I don’t know, of course. But either the whole report is a mess and puzzlingly bad science or there are gaps in it that might seem trivial to insiders.

    I always tell my students that they should not simply adopt the worst hypothesis, so perhaps I should follow that advice and say there’s a huge puzzle.

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