The Surprising Role of Sparrows in Campylobacter Risk in Dairy Barns
The impact of birds on Campylobacter transmission in dairy farms has been largely overlooked until now. To shed light on this issue, Ayala and her team conducted an extensive study at the University of New Hampshire’s Organic Dairy Research Farm, the Fairchild Dairy Teaching and Research Center, and two private dairy farms in New Hampshire. They strategically installed bird nets near cows and feed storage areas to capture birds actively interacting with the dairy environment.
The findings were striking. While various bird species were observed around the barns, the majority of birds found in close proximity to cows and feed were house sparrows. This is a crucial observation, as Ayala explains, "Many birds are present around dairy facilities, but house sparrows are unique in how directly they access feed bunks and animal areas."
The reason for this focus is Campylobacter, a bacteria transmitted through feces. Sparrows, by directly accessing feed and animal areas, may be contaminating both, thereby increasing the exposure pathways for cows. The study employs a dual sampling approach: blood samples are analyzed for antibodies indicating previous Campylobacter exposure, while fecal samples detect active infections.
Despite the existence of over 20 Campylobacter species, the research specifically targets C. jejuni due to its significance in animal, human, and environmental health. The team is also expanding its methodology to better understand bird behavior. In collaboration with UNH Associate Professor Rem Moll, they are developing a color banding system to identify individual sparrows using camera traps.
This innovative approach aims to determine which birds frequently interact with cows and feed, and whether specific individuals or movement patterns are linked to higher contamination risks. "This will help us move beyond correlation and get closer to understanding transmission dynamics," Ayala says.
The implications of these findings could be significant for dairy management. If sparrows are confirmed to initiate or amplify Campylobacter infections, it would strengthen the case for preventive strategies like vaccination programs and physical barriers such as netting to limit bird access to barns and feed storage.
From a public health perspective, the issue extends beyond animal welfare. Campylobacteriosis is the most commonly reported bacterial foodborne illness in the United States, affecting an estimated 1.5 million people annually. While outbreaks linked to E. coli or Salmonella often dominate headlines, Campylobacter infections are more widespread, frequently associated with contaminated poultry, raw milk, or water.
Although most human cases are not severe, symptoms like diarrhea, abdominal pain, and fever can persist for up to a week, making the illness disruptive and costly. Reducing Campylobacter at the farm level is, therefore, a shared priority for dairy producers, veterinarians, and public health authorities.
As Ayala’s research continues, it is expected to provide valuable insights into how wildlife interactions shape disease risks in modern dairy systems. In an era of heightened attention to biosecurity and food safety, even small animals like sparrows may have a significant impact.
