The winter months are normally a busy time for Blue Tits in our gardens. However, the latest figures from the British Trust for Ornithology (BTO) show that numbers are down, probably due to a wet summer.
During the winter months a lack of food in the wider countryside encourages both adult and juvenile Blue Tits into gardens, to make use of feeders. However, this November BTO Garden BirdWatchers reported the lowest numbers of Blue Tits in gardens since 2003, thought to be due to a lack of young birds this year.
The explanation for our missing birds can be found by looking back to the early summer. The wet weather across the breeding season, particularly in June, would have made it difficult for the adults to feed themselves and their chicks. Normally we would expect to see large numbers of newly fledged young come into gardens to seek food, but this year BTO Garden BirdWatch results show the lowest numbers of Blue Tits in August for eight years. This indicates that fewer young birds survived than usual this year and these findings are supported by the preliminary results from the BTO Nest Record Scheme (NRS) and Constant Effort Sites Scheme (CES) which found that Blue Tits had their worst breeding season on record.
Data from bird ringers show a 31% reduction in the numbers of young Blue Tits compared to the average for the last five years. This could be due in part to low numbers of eggs that were laid, with females struggling to get into good condition after a cold, damp start to the spring. Young birds leaving the nest might have also been affected by the wet June weather.
These findings certainly mirror those of a small nest box scheme which I run here in Glamorgan where Blue Tits struggled this year with lower than average clutch sizes and high chick mortality. I’ll publish the results from the last three years of that scheme on this blog in the New Year.
So, will the poor breeding season affect the number of Blue Tits we see in gardens throughout the rest of the winter and indeed affect the number of breeding adults next year? The BTO needs your help to continue monitoring their fortunes, and you can do this by signing up to the BTO’s Garden BirdWatch survey. This survey seeks information from birdwatchers about what is happening in their gardens throughout the year. It allows us to better understand garden birds and other wildlife and is excellent way to see how populations of birds like the Blue Tit are faring year on year.
To help the BTO monitor garden birds and take part in Garden BirdWatch please visit http://www.bto.org/gbw, or get in touch with the team at the BTO by emailing firstname.lastname@example.org, telephoning 01842 750050 (Mon-Fri 9am-5:00pm).