Great tits weather climate challenge

FOR IMMEDIATE RELEASE Scientists have found that a popular British suburban bird appears far more capable of adapting to a warming climate than they had suspected. LONDON, 13 July – The great tit – Britain’s favourite bird table visitor – has what it takes to keep one jump ahead of climate change. Three biologists report in the Public Library of Science journal PLoS Biology that Parus major, a little woodland bird that has already happily adapted to the suburban garden, has phenotypic plasticity, which is another way of saying that it can adapt to changing circumstances. Zoologists have been observing the same population of great tits in Wytham Woods near Oxford in the UK, for decades. Ben Sheldon of the Edward Grey Institute at Oxford University and colleagues considered the hazards that tiny short-lived birds must face as spring arrives ever earlier. The big challenge for nesting birds is to time their egg-laying to coincide with a spring peak in caterpillar numbers: if they can do this, their nestlings stand a better chance of survival and the lineage continues. But butterflies, caterpillars and their host plants have their own timetables too and, famously, the non-appearance or the late appearance of prey can be very bad news for predators. But the Oxford scientists had a lot of data to work with, and put in the field work as well: they observed the temperatures at which birds laid their eggs, they tracked the shifts in caterpillar numbers, and they kept a record of the dates of these events

Relevant across species

They confirmed that the great tits are now laying eggs on average two weeks earlier than they did 50 years ago, and did the sums. They concluded that P. major could adapt to warming of 0.5°C a year, which is rather more than the worst case scenario predicted by climate models. That is, the inheritance of the great tits included a degree of flexibility (also known as phenotypic plasticity). The study is important not because it answers questions about great tits as such but because it offers a more general way of thinking about the adaptation of the natural world to climate change. Researchers have already observed that great tits and blue tits in eastern England are vulnerable to cold snaps in spring, and respond by making their nests more cosy: the catch is that the plants they prefer for this purpose may also be vulnerable to climate change, which puts the nestlings at risk. “Our results show us under what conditions we can expect species to be able to cope with a changing environment, and under what conditions we should be more pessimistic”, Professor Sheldon said. “We should be particularly concerned about slow-reproducing species, for which the need to show just the right response to the environment is particularly crucial.” – Climate News Network