In the northeast Atlantic Flyway, a region critical for migratory birds, a recent study has raised concerns about the impact of environmental contaminants on waterfowl populations and the potential risks to hunters and consumers of wild birds. The study, published on January 15 in Science of the Total Environment, was conducted by a collaborative team including researchers from Cornell University, the New York State Department of Environmental Conservation (NYSDEC), and other state agencies. It highlights the presence of harmful chemicals in five commonly hunted species of waterfowl, with implications for both wildlife health and human consumption.
The Study’s Focus: Contaminants in Waterfowl
The research team tested over 100 waterfowl from more than 100 birds across four states—New York, Pennsylvania, New Jersey, and Connecticut—spanning nine ecological regions. Their primary objective was to assess the contamination levels in five species of waterfowl: Canada geese, wood ducks, mallards, American black ducks, and American green-winged teal. The researchers discovered detectable levels of several contaminants, including polychlorinated biphenyls (PCBs), organochlorine pesticides (OCPs), and per- or polyfluoroalkyl substances (PFAS), in every sample.
These substances are of significant concern due to their persistence in the environment and their potential health risks. PCBs, which were banned in 1979, are human-made chemicals that can accumulate in the body over time and are associated with various health issues, including cancer. PFAS, often used in industrial and consumer products, are also known for their persistence in the environment and potential toxicity. OCPs, while still in use in some places, are chemicals primarily used in agriculture that have been linked to a range of health problems.
Findings and Implications for Public Health
The study’s findings have direct implications for both wildlife health and human consumption. Among the most significant results, the researchers noted that Canada geese and wood ducks had lower levels of contaminants compared to other species like mallards, American black ducks, and American green-winged teal. The difference likely relates to feeding habits: birds that forage in cleaner environments or have less exposure to contaminated habitats tend to accumulate fewer harmful chemicals.
One of the key aspects of the study was the comparison of the contamination levels to the existing consumption advisories set by the New York State Department of Health. Current guidance recommends no more than two meals of waterfowl per month to minimize exposure to these contaminants. While these advisories may be appropriate for the general population, the study suggests that species-specific consumption guidelines may be necessary due to the varying levels of contaminants across different bird species.
Researchers found that some contaminants, particularly PCBs, posed a potential cancer risk to consumers. However, how this risk compares to the consumption of other foods is not entirely clear. The study concluded that while the levels of mercury and OCPs posed minimal risks to health for those who followed current consumption guidelines, the higher PCB levels are of greater concern. The authors stressed that more research is needed to assess the long-term health risks of consuming contaminated waterfowl.
Risk Assessment and Further Research
In assessing the health risks to consumers, researchers conducted risk assessments based on the levels of contaminants found in the birds. While the advisories suggested by the state health departments were generally conservative, the findings underscored the need for updated guidelines that take into account the specific risks associated with each species. The study provided a baseline for future risk assessments and consumption recommendations.
However, there are still many unknowns. Brenda Hanley, a co-author of the study and a research associate in the Department of Public and Ecosystem Health at Cornell University, pointed out that researchers are still unsure of the exact impact of these contaminants on waterfowl populations. “We don’t know what levels make a difference in birds or whether the different contaminants matter together or separately,” Hanley said. Moreover, there is limited understanding of how these birds compare to other wild animals that people consume, making it difficult to draw definitive conclusions about the health risks posed by hunting and eating wild waterfowl.
One of the study’s primary conclusions is the need for further research on how these chemicals affect waterfowl. Specifically, researchers are interested in understanding the long-term impacts of these contaminants on the survival and reproductive success of these species. While the study provided important data on contaminant levels in waterfowl, it raised several questions about the effects on bird populations that cannot yet be answered with the available data.
Conservation Concerns
Beyond the direct health risks to humans, the study also raises alarms about the broader environmental impact of these contaminants on wildlife. As Krysten Schuler, the senior author of the study and a wildlife disease ecologist at the Cornell Wildlife Health Lab, pointed out, the contamination of waterfowl is another indicator of the ongoing environmental crisis. “These animals are constantly losing wetlands and habitats and being forced into less desirable locations,” Schuler said. “This just highlights the importance of protecting those areas for these species.”
Habitat loss, combined with rising contamination levels, poses a significant threat to waterfowl populations. As migratory birds increasingly rely on fragmented or polluted habitats, their exposure to harmful chemicals becomes a compounded issue. These environmental stressors, coupled with the potential health risks of consuming contaminated birds, underscore the need for stronger conservation efforts.
A Collaborative Effort in Data Collection
The study also stands out for the collaborative effort involved in collecting data from the wild waterfowl population. Biologists from various state wildlife and conservation agencies worked together to collect birds from hunters who volunteered to participate in the study. These birds were then processed by the Wildlife Health Lab at Cornell University, where they underwent extensive testing for contaminants.
David Dayan, the first author of the study and a recent graduate of Cornell, played a key role in both the hands-on preparation of the birds and the subsequent data analysis. “Trying to paint a coherent picture from all of these different perspectives and data points was a really interesting way to do science,” Dayan said, reflecting on the complexity of the study.
This large-scale collaboration, involving biologists, wildlife managers, and researchers from multiple states, was essential for producing the comprehensive data needed to assess contamination levels across various species and ecological regions. The study’s findings provide a crucial baseline for future research and policy development regarding the safety of consuming wild-caught waterfowl.
A Call for Updated Guidelines
The study has important implications for policy and regulation. In New York, the consumption guidelines for wild-caught waterfowl have not been updated since the early 1990s. As Schuler and her colleagues noted, their findings provide valuable new data that can help health departments in all four states involved in the study—New York, Pennsylvania, New Jersey, and Connecticut—reevaluate existing consumption guidelines and, if necessary, craft new recommendations based on the contaminants found in waterfowl.
“This provides a really good baseline,” Schuler said. “We’re not telling people what to eat or do. We’re just providing the numbers.” The study’s role is not to dictate behavior but to inform public health recommendations based on the most current data available.
Conclusion: A Broader Implication for Environmental and Public Health
This study is a critical step in understanding the environmental and health risks associated with hunting and consuming wild waterfowl in the northeast Atlantic Flyway. The widespread contamination of waterfowl with harmful chemicals like PCBs, OCPs, and PFAS underscores the need for continued monitoring and more comprehensive research into how these contaminants affect both wildlife populations and human consumers.
As Schuler pointed out, while much of the focus has been on understanding the impact of these chemicals on the birds themselves, there is also a pressing need to understand the broader environmental implications. Protecting habitats and reducing environmental contamination are essential to safeguarding the future of waterfowl populations, which play an integral role in the ecosystems of the northeast Atlantic Flyway.
In the meantime, consumers and hunters should be aware of the potential risks associated with consuming wild waterfowl, following local consumption guidelines, and remaining informed as more research is conducted on the long-term health impacts of these contaminants. Ultimately, this study serves as both a warning and a call to action to protect wildlife, human health, and the environment for future generations.
Reference: David B. Dayan et al, Environmental contaminants assessment for frequently harvested migratory waterfowl in the Northeast Atlantic flyway, Science of The Total Environment (2025). DOI: 10.1016/j.scitotenv.2025.178474