Fig. 1.

The relationship between global mean temperature anomalies (GMTA) and feather moult extent. a The extent of post-juvenile moult of 19 passerine species, shown separately for each species (thin lines ± 95% confidence intervals, CIs) and the general trend (bold line ± CIs). The trend indicates a significant increase of moult extent with increasing GMTA in 16 species (∆AICc ≥ 2.10; Supplementary Table 3). The two circled insets depict the extent of wing moult in the beginning and the end of the examined period (1805–2016). The boxed inset illustrates the general trend of moult extent across the study period (years). b Male and female moult extent of 10 sexually dichromatic passerine species throughout the examined period, shown separately for each species (thin lines ± CIs) and the general trend (bold line ± CIs). In four species, the results indicate a stronger response to warming climates in females than in males (∆AICc ≥ 3.80), leading to an overall more extensive moult of females than that of males since ~1990. Thus, in these species, females replaced more feathers than males under warmer conditions. c Two examples demonstrating how the increasing extent of moult changed the appearance of a first year male Collared Flycatcher Ficedula albicollis (top two illustrations) and Eurasian Blackbird Turdus merula (bottom two illustrations) before 1900 (left) compared to 2015 (right). Since the birds moulted more feathers in recent years, their present-day plumage appears more similar to that of adult birds