Breeding birds of high-elevation mixed-conifer forests have declined in national parks of the southwestern U.S. while lower-elevation species have increased, with responses to drought varying by habitat.

This article focuses on how climate variables, specifically drought and the timing of North American monsoon rainfall, influence breeding-season densities of bird species across diverse habitats and elevations in six national parks on the Colorado Plateau in the southwestern United States. Using a 12-year dataset (2007–2018) and Bayesian hierarchical N-mixture models, the study found that bird population trends and climate responses vary by habitat: high-elevation mixed-conifer forest species generally declined, likely due to climate-driven habitat loss and disturbance, while lower-elevation pinyon-juniper and grassland-shrubland species often increased. Drought effects were positive for montane forest birds, neutral for pinyon-juniper species, and negative for grassland-shrubland species, whereas earlier monsoon rains benefited molt-migrant species that stopover in the monsoon region but negatively affected grassland birds, possibly due to storm-related nest failures. The findings highlight the importance of habitat- and elevation-specific approaches to understanding and conserving southwestern bird populations under changing climate conditions.