West LA Times

North American birds are altering their locations and annual behaviors in response to global warming, according to a new UCLA study. The research, which analyzed 27 years of data across 311 land-based species, found that more than half of the changes are through phenology—adjustments in annual cycles such as breeding times—rather than shifts in latitude and elevation.

As North America experiences rising temperatures due to climate change, animals typically respond by moving north, heading to higher elevations, or making phenological changes. This study is notable for examining all three primary responses simultaneously, offering a comprehensive view of how various bird species are adapting.

Birds are generally moving away from heat by migrating northward in latitude and upward in elevation while also advancing their breeding seasons. However, these adaptations are not sufficient to keep pace with the rate of climate change. Adjustments made by birds only account for one-third of what would be needed to match the speed of warming.

"Of the temperature tracking we’ve observed in birds, 64% is due to phenology tracking alone," said Monte Neate-Clegg, UCLA ecologist and lead author of the study. On average, birds are advancing their breeding dates by 0.08 days per year. This minor adjustment may represent an easier method compared to moving long distances or finding new habitats at higher elevations.

"This is a response we’ve hypothesized before, particularly for birds from California," said Morgan Tingley, a UCLA professor of ecology and evolutionary biology and senior author of the study. "But now, for the first time, we can see how animals are using multiple ways simultaneously to adapt to climate change."

The study revealed that birds move an average of just 1.1 kilometers northward and 1.2 meters upward annually. However, there is significant variation among species; some like the lesser goldfinch move rapidly northward and breed earlier while others like the black phoebe shift southward and downward due to factors such as urbanization and habitat availability.

Understanding these adaptations is crucial for conservation efforts. The fact that many birds adjust their breeding timing suggests that conservation strategies should consider both habitat protection and ecological event timing.

"In order to best target our conservation efforts, we need to know how species are and are not adapting to ongoing climate change," Tingley emphasized. "While shifting the timing of nesting may help birds in the short term, if they do not move in the long term, greater conservation efforts are likely necessary."