Modelling how birds mistime egg-laying due to climate change

Egg laying

Many birds have to time egg-laying to coincide with a peak in food availability, for example , to match the hatching shcedule of a particular type of caterpillar. This is a tricky business because many caterpillars are available for only a few weeks and the birds must lay their eggs around a month in advance to hit the peak. Needless to say, nobody is quite sure how birds do it.

The situaiton has recently become more complicated because a warmer climate in many habitats is causing caterpillars to advance their hatching date. How birds are coping with this is being increasingly studied.

Daniel Campos, a mathematician at the University of Manchester, and a few buddies have come up with a few predictions based on evolutionary game theory, in which agents compete, learn, evolve and are selected for or against. This team’s particular focus is on evolutionary minority games in which agents are rewarded for behaving in a way that puts them in a minority.

It turns out that evolutionary minority games are pretty good models of many real world situations in which individuals compete for a limited resource. That’s because those in the minority have fewer competitors and so are more likely to survive. Campos and co say that the way birds compete for food aftr egg laying is one of these situations and that their model can be used to make some predictions about the behaviour of birds as food resources change.

Their main result seems to be that the best learners among bird species should adapt more easily to changing hatching schedules. But there is a caveat: if the food resource isn’t scarce, this doesn’t apply.

That’s more or less what the ornithologists had predicted themsleves without the help of sophisticated computer models. And it seems to match the observations that some birds have adapted their laying because of a change in the timing of a food peak. Of course, other species haven’t changed and nobody knows whether this is because the birds are poor learners or because there are alternative food sources available, or for some other reason. And all this is against the backdrop of a very limited knowledge about bird learning abilities in the first place.

All in all, this a slightly unsatisfying contribution to a debate that will reach fever pitch as more observational data comes in. But the authors appear to acknowledge this in the title of their paper: “Limited Resources and Evolutionary Learning may help to Understand the Mistimed Reproduction in Birds caused by Climate Change”. Then again, it may not.

Ref: Limited Resources and Evolutionary Learning may help to Understand the Mistimed Reproduction in Birds caused by Climate Change

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