The latest report, Population estimates of birds in Great Britain and the United Kingdom shows that the Wren continues to hold the title of our commonest bird – the last report in 2013 also had Wren at the top of the list but with a population of just over 8.5 million pairs. Wren numbers are known to fluctuate according to environmental conditions and it may be that generally milder winters are benefitting one of our smallest birds.

Source:
Discover Wildlife
Rare Bird Alert UK