The Long-tailed Tit (Aegithalos caudatus) has a tail that is bigger than its body – up to 8cm – and an undulating flight. It builds elastic nests that can actually expand to accommodate their growing chicks. It can take up to 3 weeks to build the nest, which is lined with more than 2,000 feathers. Sexes are identical. The Long-tailed Tit is an abundant breeding resident in the UK with over 250,000 pairs, but also occurs across Eurasia to Japan, giving it the most widespread distribution of any species in its family.