Long-tailed tits only live for two or three years, and it has long been thought that large numbers died during cold winters. However, according to a 20-year study published in Oikos, warm spring weather actually holds the key to their survival.
‘For most small birds that live for only two or three years, not raising any chicks one year is a disaster,’ said the study’s lead author, Philippa Gullett of the University of Sheffield. ‘They might only get one more chance, so they can’t afford to fail.’
Hence, the birds invest all their reserves in reproduction, to the point of risking death to ensure that their young survive. The researchers found that during warm, dry springs, breeding tits have a much better chance of surviving to the next year. ‘What seems to be going on is that the tits try to raise their chicks at any cost,’ said Gullett. ‘If it’s cold and wet in spring, that makes their job much tougher. Food is harder to find; eggs and chicks are at risk of getting cold. By the end of the breeding season, the adult birds are exhausted.’
‘Looking ahead, our data suggest that every single plausible climate change scenario will lead to a further increase in long-tailed survival rates. While many species struggle to adjust to climate change, these delightful birds seem likely to be winners,’ said one of the study’s co-authors, Karl Evans of the University of Sheffield.
This story was published in the May 2014 edition of Geographical Magazine