More than 25% of species assessed by the International Union for Conservation of Nature (IUCN) are threatened with extinction. Understanding how environmental and biological processes have shaped genomic diversity may inform management practices. Using 68 extant avian species, we parsed the effects of habitat availability and life-history traits on genomic diversity over time to provide a baseline for conservation efforts. We used published whole-genome sequence data to estimate overall genomic diversity as indicated by historical long-term effective population sizes (N e) and current genomic variability (H), then used environmental niche modelling to estimate Pleistocene habitat dynamics for each species. We found that N e and H were positively correlated with habitat availability and related to key life-history traits (body mass and diet), suggesting the latter contribute to the overall genomic variation. We found that H decreased with increasing species extinction risk, suggesting that H may serve as a leading indicator of demographic trends related to formal IUCN conservation status in birds. Our analyses illustrate that genome-wide summary statistics estimated from sequence data reflect meaningful ecological attributes relevant to species conservation.