A few decades ago, bald eagles were a story of conservation success. They were saved from extinction, and their rebound added stronger respect to them as the USA’s national symbol. 

What the country has achieved, however, is facing a drawback that may send the eagles back to concerning population status. 

According to new research from the University of Georgia, the highly infectious avian flu, also known as H5N1, has been killing a large number of mating pairs of bald eagles. 

Lead author Nicole Nemeth said that just one year of losses of productivity which the researchers had documented regionally was concerning. Moreover, such losses, if they had happened in broader regions, could have had impacts for decades to come. 

“There were nights where I couldn’t sleep based on what we were hearing and seeing. We have already lost unprecedented numbers of wild birds due to this virus in the U.S. and it appears here to stay,” Nemeth said. 

Wild birds in danger due to the bird flu 

Back in April 2022, it was confirmed that the pathogenic avian influenza had hit Georgia’s eagle populations. In the previous month, there were three dead eagles found in Chatham, Glynn and Liberty counties. 

And around that time, the USDA had confirmed about 660 cases of the H5N1 virus in wild birds, only 11 of which were from Georgia. Unfortunately, since then, the number has ascended to more than 6200 reported cases around the country. 

Eagles aren’t the only wild birds dying off due to the virus. Those cases include different vultures and other raptors, waterfowl like geese and ducks, as well as other aquatic birds like pelicans and herons. Some songbirds, although they’re less affected by the virus, are also on the list of H5N1 cases. 

Let’s also not forget about the millions of farmed poultry that have died or been culled to prevent further infection. 

Nemeth added that the reported wild bird cases are getting less factual. “People will submit one snow goose, for example, and it will test positive for the virus. And then they’ll tell you, ‘Well, there are thousands of geese dying at the same site.’ But it only goes down as one infected bird,” Nemeth said. 

 

 

Drastic decrease of fledging in Georgia in 2022 

According to the researchers, just under half of bald eagle nests along coastal Georgia successfully fledged at least one eaglet last year—30% below average for the region. 

There’s also decreased fledging in other counties. For example, one part of Florida saw only half of the average success rate for the nests, from 85.5% to 41%. Another Florida county had a less dramatic but still concerning decrease from an average of approximately 78% to 66.7%. 

Nemeth added that the reports were recorded from people who had been tirelessly monitoring eagle nests each year. The reports were “heartbreaking stories of an adult eagle found dead below their nest. Within a few days, often its mate and the chicks were also found dead below the nest. It is clear the virus is causing nest failures,” Nemeth said. 

Already dealing with change of food source 

Despite the relatively safe situation before the outbreak of H5N1, bald eagles have also had to adapt with the change of their food source due to climate change. A study published in the journal Ecosphere suggests that this change has made them rely more on farmlands. 

Before, eagles would feed off salmon carcasses for their winter diet. But, there’s a declining availability of salmon carcasses in the past 50 years, made worse by climate change. 

Lead author of this study Ethan Duvall said, “Climate change has altered the chum salmon spawning schedule, causing them to run earlier in the winter. Now the salmon are spawning when annual Nooksack River flooding is at its peak. The fish who spawn and die are swept away by the high water instead of being deposited on shore where the eagles can easily access them.” 

The change in timing, according to Duvall, has reduced the number of available carcasses on the local river, not the number of individual salmon. But, rivers in the Pacific Northwest have experienced dramatic salmon population declines, also eliminating winter resources for eagles.  

Together with the fact that bald eagles were increasing more and more before the virus hit, the raptors shifted their focus on farms. Per the researchers, this recent relationship is mutually beneficial. 

 

 

Turning to farms 

To understand the human-raptor relationship, Duvall and the team interviewed farmers on small, medium, and large dairy operations in Whatcom County.  

They found that recently, since the eagles don’t have enough food in their natural food supply, they’ve searched for food around farmlands. More specifically, in the area where there’s steady stream of dairy farm by-products resulting from the births and deaths of cows. 

Other than farm by-products, they’ve also preyed on waterfowl populations which feed and rest in the agricultural areas. If the two still aren’t enough, well, they can always hunt good old farm pests. 

According to Duvall, his study paints eagles-farms relationship in a better picture, as the farmers didn’t mind them. “Dairy farmers in northwestern Washington do not consider the eagles threats. In fact, many farmers appreciate the services that the eagles provide such as carcass removal and pest-deterrence.” 

However, this positive interaction may not be the same in conventional or free-range poultry farms, where the eagles can simply snatch chickens. 

“But this study gives me hope that, moving forward, farmers, wildlife managers, and conservationists can come together to think critically about how to maximize benefits for people and wildlife in the spaces they share,” Duvall said. 

Persistent virus that threatens not just avians 

Given the right conditions, H5N1 is able to survive in water for over a year. This poses risks of infection to birds that live in coastal or other aquatic areas. Birds can pick up the virus from spending time in the water and then carry it to new locations when they migrate. 

Avians that eat other birds like eagles and vultures will contact the virus once they consume infected birds. And considering bald eagles like being near farmlands now, it’s possible that some of them might have died from eating infected chickens. 

“Worst case scenario, we get into a scary place with some of these bird species. We could see a lot more decline in the numbers of eagles, raptors, waterfowl and other birds than what we’ve already seen. It could be devastating,” Nemeth said. 

Now, the birds are not the only ones affected with this virus. There are reports of infection in wild mammals such as red foxes, coyotes, racoons, seals, opossums and even some bears in North America.  

Furthermore, according to the Centers for Disease Control and Prevention, there are also a few people infected with the virus, but they’ve recovered with minimal symptoms. 

 

 

Can the virus be contained? 

According to the University of Georgia study, no, unfortunately. And it’s already present everywhere now.  

As grim as it sounds, it is what it is for now. But I think this has given us an opportunity to learn about the virus itself. And in the meantime, we can also focus more on prevention in other existing populations in different areas as well as conservation. 

“We can’t contain the virus, and we can’t vaccinate wild birds. But we can document the losses and try to help conserve affected species and populations the best we can” 

In my opinion, this case teaches us about how precious the life of wild birds is. One time, it seems like they’re thriving, but another time, something unexpected can whisk them away.  

Let’s just hope that the eagles can get more resilient to the virus and eventually recover from the population drop. I would want to see wild eagles perching up the trees or fly high or still be living symbols. 

 

Sources

https://www.sciencedaily.com/releases/2023/03/230302093346.htm  

https://www.sciencedaily.com/releases/2023/03/230314110712.htm