UCLA researchers are working on a predictive tool to help prevent salmonella outbreaks among wild songbirds, which can also pose risks to people, pets, and poultry. The research is published in Proceedings of the National Academy of Sciences.
The team observed that in years when pine cone production is low, certain forest songbirds migrate in large numbers into urban areas and gather around bird feeders. This crowding increases the risk of salmonellosis, a disease caused by the Salmonella bacterium. For example, during the winter of 2020-2021, the Centers for Disease Control and Prevention traced an outbreak that affected people and a dog to pine siskins spreading bacteria at backyard feeders.
“While it’s something that brings us pleasure and generally seems to have neutral or in some cases net positive ecological impacts, there are situations in which the gathering together of birds is bad for bird and human health,” said Morgan Tingley, senior author and UCLA professor of ecology and evolutionary biology. “We don’t want people to stop feeding birds, so we’re trying to develop a tool that will predict when there will be millions of extra birds flooding urban bird feeders so people can temporarily take them down.”
Tingley and lead author Benjamin Tonelli developed their model by analyzing 40 years of data from four sources: a USGS database on wildlife disease outbreaks, Audubon Christmas Bird Count records for population estimates, academic studies on pine cone production (masting), and climate data from NASA’s Daymet project. They found links between climate variations, tree cone production cycles, irregular bird migrations known as irruptions, and outbreaks of salmonellosis.
Their findings showed that major differences in yearly temperatures could cause forests to produce fewer pine cones. When this happens, songbirds move into cities in greater numbers. In western North America these events were more intense compared to eastern regions.
Bird-related activities remain popular across the United States; about one-third of American adults engage with birds through observation or feeding, with 40–50 million buying bird seed annually. Songbirds can transmit Salmonella by contaminating feeders with droppings; other animals including backyard chickens and dogs may also become infected.
“The good news is that the last major salmonella outbreak was in 2020-2021, so they’re not happening every year,” said Tonelli, now a postdoctoral researcher at Clemson University. “You can feed your birds basically 99% of the time without having to think about this. But there is going to be a time and a place where the best thing you can do to protect your backyard birds is to take down your feeders.”
Tonelli noted that their predictive model indicates an average season ahead for both western and eastern regions regarding irruptions and disease risk: “So far this year, it predicts a pretty average season in both regions for irruptions, and therefore pretty average risk of disease outbreaks, which means not heightened really at all.”
This research highlights UCLA’s ongoing commitment as a public research university focused on generating knowledge for societal benefit while promoting academic excellence and diversity across its programs (official website). The university draws students from California and around the world through its broad range of disciplines (official website).
The study received funding from NASA’s Earth and Space Science and Technology division.
