New Study Finds Delayed Long-Distance Bird Migration Due to Climate Change

There has been an unexpected and rapid shift in migratory timing for a population of a long-distance migratory bird, potentially due to climate change, according to a new study from the Department of Environmental Conservation at the University of Massachusetts Amherst that was published in Proceedings of Royal Society B.

Lauren Puleo is the study’s lead author and a member of the Senner Lab at UMass. Nathan Senner is Mass Audubon’s Bertrand Chair of Ornithology and founded the Senner Lab to understand how individual-level processes scale up to influence population- and species-level processes.

The study focused on Hudsonian Godwits, which have one of the longest migrations of any bird species. They travel from southern South America to Alaska and Canada each spring to breed, including a 6–7-day nonstop flight from Chile to the mid-continental U.S. After four decades of arriving increasingly early to their breeding grounds in response to climate change, one godwit population is now arriving nearly a week later than they did a decade ago.

As the global climate has warmed, springs have begun arriving increasingly early. To keep pace with these earlier springs, migratory birds have had to migrate northward earlier in spring. If a species is unable to arrive earlier, they risk missing out on the resources they need to successfully raise their young. Such climate change-induced mismatches are thought to be one of the drivers of the population declines of many migratory species.

The study, which followed the migrations of an Alaskan breeding population of Hudsonian Godwits over the course of 12 years, found that this species is instead migrating later and that this may be having especially negative consequences for their ability to reproduce.

The UMass Amherst-based team of researchers found that Hudsonian Godwits arrived 6 days later in 2023 than they did in 2012. These delays occurred despite the fact that godwits continued to complete their spring migrations in around three and a half weeks throughout the study period. Godwits were thus departing southern South America 6 days later in 2023 as well, suggesting that conditions in South America may be causing the change.

“Arriving to Alaska on time in spring is key to the ability of young godwits to grow during the short sub-Arctic summer,” said Lauren Puleo, the graduate student who led the study. “If adult godwits arrive too late, it is impossible for them to lay their nests quickly enough to ensure that their chicks have sufficient food.” 

The authors used miniature tracking devices to follow the movements of individual godwits across the globe. They tracked dozens of godwits between 2010 and 2023 and combined these data with information on climatic changes across the godwit migratory route to assess when godwits should be expected to arrive on their breeding grounds in Alaska.

The populations of many migratory bird species that breed in North America are in steep decline, and Hudsonian Godwits are thought to be among those declining most rapidly. “The plight of godwits and other migratory species is dire. It is urgent that we gain a better understanding of what determines when godwits and other birds migrate and identify ways to mitigate the consequences of them arriving too late to successfully breed,” says Dr. Nathan Senner, the senior author and the Mass Audubon Bertrand Chair for Ornithology in the Department of Environmental Conservation at UMass.

For more information on the Senner Lab, visit sennerlab.com.