Realized climate niche breadth varies with population trend and distribution in North American birds

Ecological niche theory states that realized niche breadth should increase with population growth. This relationship has been studied extensively in the context of density-dependent habitat selection, and there is evidence that animal populations at higher density occupy a wider range of vegetation types. To our knowledge, no previous studies have investigated the relationship between population growth and climate niche breadth (i.e. the range of climatic conditions occupied). Here we aim to estimate the influence of population trend, as well as changes in distribution, on realized climate niche breadth.