Figure 3: Survival of grey and brown tawny owls in relation to changes in snow depth.

Survival estimates are based on averaging all candidate capture–mark–recapture models considering the effects of food supply (vole abundance), average snow depth and average temperature during a critical period in winter (see Supplementary Information). Climatic data are derived from the database of the Finnish Meteorological Institute. (a) Survival of brown and grey tawny owl colour morphs in relation to snow depth. (b) Snow depth during the critical period for tawny owl survival during 1981–2008 in Southern Finland. (c) Survival of grey and brown tawny owl colour morphs during 1981–2008. Grey tawny owls are denoted by grey circles and brown ones by red diamonds. Error bars are standard errors of the estimated survival and the lines are regression slopes based on the data.