A study of Northern Hemisphere waterfowl suggests that environmental diversity and human activity significantly impact the transmission of H5N1.
RT’s Three Key Takeaways:
- Environmental Impact on Movement: Researchers found that waterfowl in diverse landscapes, such as those with urban green spaces and wetlands, travel significantly shorter distances than birds in uniform agricultural areas.
- Seasonal Transmission Risks: The study revealed that winter movement distances are more than twice as long as those during the breeding season, potentially facilitating a wider spread of the virus.
- Predicting Disease Outbreaks: By analyzing weekly movement patterns that align with the one-week incubation period of highly pathogenic avian influenza (H5N1), scientists may be able to better predict where bird flu will spread next.
The movement patterns of waterfowl, including ducks, swans, and geese, may affect the spread of H5N1 in bird populations, according to a study from the University of Georgia published in Ecology Letters.
Researchers analyzed 20 years of data containing movement information from more than 4,600 waterfowl across 26 species in the Northern Hemisphere. The study tracked how far the waterfowl moved over time during breeding and winter seasons, when birds commute regularly between areas used for resting and eating.
The distance of these commutes, which occurred outside of regular seasonal migrations, appeared to depend on the birds’ environment. Waterfowl in uniform areas, such as large expanses of grasslands or farmlands, traveled six times farther to acquire food or a safe location to rest compared to birds in more diverse landscapes.
In more varied landscapes, which included wetlands and urban green spaces, waterfowl often did not need to travel more than a mile around their home to meet their daily needs.
“Birds are like us. They’re always responding to what’s around them, whether that’s food availability or disturbance from people or other animals,” said Claire Teitelbaum, assistant unit leader with the US Geological Survey’s (USGS) Georgia Cooperative Fish and Wildlife Research Unit and lead author of the study, in a news release. “We can take the environment, predict how much we think birds are moving and then use that to predict where avian flu is going to go.”
Locations with a significant human population also played a role, as they were more likely to have protected green spaces with water sources or cover. Human activity could also create physical barriers that prevent bird movement, such as roads or fences. Birds in these regions traveled about one-third of the distance of birds residing in sparser areas.
While yearly migrations are a major factor in the spread of H5N1, the study aimed to understand how flight during breeding and winter seasons may add to transmission. The researchers found that during winter months, movements were over twice as far when compared to travel during the breeding season. Waterfowl often had to fly farther in their daily routines to secure food or places to sleep, potentially carrying the virus with them.
In addition to studying these daily movements, the researchers found the same patterns when studying birds’ weekly movement distances. This is a significant finding because one week is also the incubation period for the virus, according to the study.
Breeding season presented its own challenges, as birds were less likely to travel far distances and remained close to their nests. Although this can limit wider spread, it could also increase the risk for localized hotspots of the virus.
“If we want to keep the flu from spreading, we might want to see what we can do to keep the birds in one place, but there’s that flipside. Outbreaks happen when birds are in high density, so we might have increased transmission locally,” said Teitelbaum, who also serves as an adjunct assistant professor in the Warnell School of Forestry and Natural Resources. “That’s the underpinning: How can we link the distances that birds are moving to the distances that flu is moving?”
