Understanding wild waterfowl use of retention ponds at commercial poultry farms – a potential route for avian influenza virus transmission
Retention ponds on commercial poultry farms are used by wild waterfowl, representing a potential pathway for the transmission of avian influenza viruses between waterfowl and farmed poultry. Managing vegetation conditions surrounding ponds may be one way to reduce their use by waterfowl.
Issue
The Delmarva Peninsula, comprised of Delaware and the eastern shores of Maryland and Virginia, is home to a poultry industry that produced roughly 596 million chickens in 2022 alone. The peninsula also provides stopover and overwintering habitat for waterfowl migrating within the Atlantic Flyway. However, the spatial convergence of large numbers of wild waterfowl and hundreds of millions of farmed birds may facilitate the transmission of avian influenza viruses (AIV), as the presence of wild waterfowl on the landscape is the most important element in AIV transmission. One potential way for these viruses to enter commercial poultry flocks is when wild waterfowl use retention ponds near poultry houses. Although these ponds are meant to control nutrient runoff and minimize the environmental impacts of poultry operations, their attraction of waterfowl could possibly increase the risk of AIVs being entering poultry houses. Notably, very little is known about wild waterfowl use of retention ponds on commercial poultry farms. Filling this knowledge gap can shed light on the possible role of these ponds in facilitating the transmission of AIVs, like highly pathogenic avian influenza, from wild to farmed birds and can inform actions meant to make these ponds less attractive to waterfowl.
USGS Study
To better understand the potential for retention ponds near commercial poultry facilities to serve as a route of AIV transmission, USGS researchers conducted a preliminary investigation to (a) gather data on the presence of waterfowl species on these ponds and (b) assess how habitat characteristics around ponds relate to the diversity and abundance of waterfowl using ponds. The study took place in Dorchester and Somerset counties along the eastern shore of Maryland bordering the Chesapeake Bay. Researchers surveyed 12 retentions ponds one to two times per week from September 2022 through March 2023, resulting in a total of 440 site surveys. During surveys, researchers noted the number of each waterfowl species present on and within 10 m of each pond. Investigators also recorded habitat conditions at survey locations, noting the vegetation conditions buffering ponds, pond size, and the distance from each pond to the nearest public road.
Major Findings
- Researchers observed 10 species of waterfowl at 9 of the 12 surveyed retention ponds, indicating potential for such ponds to serve as a an interface for the transmission of avian influenza. Although Canada geese (Branta canadensis) were the most widespread and most numerous species observed, the use of ponds varied among different waterfowl over the course of the survey period (fig. 1). For example, whereas mallard (Anas platyrhynchos) and Canada goose observations appeared to follow the fall migratory trends of these species, observations of diving duck species were more variable and less common over the survey period.
- The study also found that habitat conditions around ponds seemed to influence waterfowl observations. Whereas ponds surrounded by open vegetation tended to attract the most species and the largest number of individuals, those surrounded by trees tended to attract the fewest number of species (fig. 2). The size of ponds and the distance of ponds to the nearest road had no consistent influence on waterfowl diversity or abundance.
Management Applications
This study offers a preliminary look into wild waterfowl use of retention ponds on commercial poultry farms and what conditions may influence their use. Although these retention ponds are meant to control nutrient runoff associated with poultry farming, their birdslocation may bring wild waterfowl in closer proximity to commercial houses. While this study did not explicitly examine different management actions for reducing waterfowl use of retention ponds, it did identify promising risk abatement actions worthy of further study, such as how vegetation management around ponds might be one way to influence the attractiveness of ponds to waterfowl.
More Information
Retention ponds on commercial poultry farms are used by wild waterfowl, representing a potential pathway for the transmission of avian influenza viruses between waterfowl and farmed poultry. Managing vegetation conditions surrounding ponds may be one way to reduce their use by waterfowl.
Issue
The Delmarva Peninsula, comprised of Delaware and the eastern shores of Maryland and Virginia, is home to a poultry industry that produced roughly 596 million chickens in 2022 alone. The peninsula also provides stopover and overwintering habitat for waterfowl migrating within the Atlantic Flyway. However, the spatial convergence of large numbers of wild waterfowl and hundreds of millions of farmed birds may facilitate the transmission of avian influenza viruses (AIV), as the presence of wild waterfowl on the landscape is the most important element in AIV transmission. One potential way for these viruses to enter commercial poultry flocks is when wild waterfowl use retention ponds near poultry houses. Although these ponds are meant to control nutrient runoff and minimize the environmental impacts of poultry operations, their attraction of waterfowl could possibly increase the risk of AIVs being entering poultry houses. Notably, very little is known about wild waterfowl use of retention ponds on commercial poultry farms. Filling this knowledge gap can shed light on the possible role of these ponds in facilitating the transmission of AIVs, like highly pathogenic avian influenza, from wild to farmed birds and can inform actions meant to make these ponds less attractive to waterfowl.
USGS Study
To better understand the potential for retention ponds near commercial poultry facilities to serve as a route of AIV transmission, USGS researchers conducted a preliminary investigation to (a) gather data on the presence of waterfowl species on these ponds and (b) assess how habitat characteristics around ponds relate to the diversity and abundance of waterfowl using ponds. The study took place in Dorchester and Somerset counties along the eastern shore of Maryland bordering the Chesapeake Bay. Researchers surveyed 12 retentions ponds one to two times per week from September 2022 through March 2023, resulting in a total of 440 site surveys. During surveys, researchers noted the number of each waterfowl species present on and within 10 m of each pond. Investigators also recorded habitat conditions at survey locations, noting the vegetation conditions buffering ponds, pond size, and the distance from each pond to the nearest public road.
Major Findings
- Researchers observed 10 species of waterfowl at 9 of the 12 surveyed retention ponds, indicating potential for such ponds to serve as a an interface for the transmission of avian influenza. Although Canada geese (Branta canadensis) were the most widespread and most numerous species observed, the use of ponds varied among different waterfowl over the course of the survey period (fig. 1). For example, whereas mallard (Anas platyrhynchos) and Canada goose observations appeared to follow the fall migratory trends of these species, observations of diving duck species were more variable and less common over the survey period.
- The study also found that habitat conditions around ponds seemed to influence waterfowl observations. Whereas ponds surrounded by open vegetation tended to attract the most species and the largest number of individuals, those surrounded by trees tended to attract the fewest number of species (fig. 2). The size of ponds and the distance of ponds to the nearest road had no consistent influence on waterfowl diversity or abundance.
Management Applications
This study offers a preliminary look into wild waterfowl use of retention ponds on commercial poultry farms and what conditions may influence their use. Although these retention ponds are meant to control nutrient runoff associated with poultry farming, their birdslocation may bring wild waterfowl in closer proximity to commercial houses. While this study did not explicitly examine different management actions for reducing waterfowl use of retention ponds, it did identify promising risk abatement actions worthy of further study, such as how vegetation management around ponds might be one way to influence the attractiveness of ponds to waterfowl.