blickwinkel / Alamy Stock Photo
Blue tits divorce their partners if they turn up late to annual breeding season.
About 85 per cent of birds are socially monogamous, meaning they form couples and share the workload of raising their young. Staying together long-term is thought to be beneficial because they can focus on breeding and parenting rather than having to look for new mates.
However, break-ups have been observed in 92 per cent of these socially-monogamous species, including blue tits.
To work out why some blue tits divorce, Carol Gilsenan at the Max Planck Institute for Ornithology in Germany and her colleagues studied over 100 breeding pairs in a southern German forest for 8 years. The birds were microchipped to identify when they visited 277 breeding boxes in the area.
The study revealed advantages to being faithful: females that mated