Birds could be at increased risk on migration and at wintering grounds – Milwaukee Journal Sentinel

You’ve likely seen news this year of a bird flu that’s taking an unprecedented toll on U.S. domestic and wild birds.
The H5N1 strain of highly pathogenic avian influenza (HPAI) has killed or caused to be destroyed 53.4 million domestic birds in the U.S., according to U.S. Department of Agriculture figures released Tuesday.
That tops the previous high in 2014 and 2015 when a different strain affected 49 million domestic birds and cost $1 billion. The USDA proclaimed that outbreak as “the most costly animal health emergency in U.S. history.”
This year’s economic losses have yet to be tallied.
Unfortunately the toll on wild birds from the current strain of HPAI is also greater and by a much wider margin than has been seen in commercial flocks.
According to USDA statistics, 5,001 wild birds have been confirmed with the disease across the continent. West Virginia is the lone state without a documented case.
In the 2014-15 outbreak only 98 HPAI-positive wild birds were detected, according to the USDA.
But the data on wild birds is misleading. Wildlife experts say the vast majority of infected birds are never found or tested in the wild.
Reports from the field are a much better indicator of the toll the H5N1 strain is taking of wild birds.
In Wisconsin, HPAI ravaged a breeding colony of Caspian terns in Door County and is the suspected cause of extremely low survival of bald eagle chicks this year.
In Illinois, the virus is the suspected cause of death of several hundred snow geese found in fields earlier this month, according to the Illinois Department of Natural Resources. In Washington, the disease is linked to 700 birds found dead this month in Skagit Bay.
Internationally, HPAI is also hitting wild birds hard. At least 5,200 cranes in the Hula Valley of Israel were found dead last December while on their migration to Africa, according to a summary by The Wildlife Society.
Israeli Environmental Protection Minister Tamar Zandberg called the bird flu outbreak “the most serious damage to wildlife in the history of the country.”
The virus has been eye-catching to say the least.
So consider the potential impact of HPAI on an endangered species with a worldwide population numbering in the hundreds.
Take the whooping crane, for example.
The staff at the International Crane Foundation in Baraboo has been keenly watching the disease and taking precautions to protect captive birds at its headquarters.
“We’ve had our eye on this issue since the early 2000s,” said Dr. Barry Hartup, a veterinarian and ICF’s director of conservation medicine. “We got especially involved with it in 2005 when there was a massive outbreak on wild birds in China.” 
Cranes are among the most endangered families of birds in the world, with 10 of the 15 species threatened. So a disease outbreak could be devastating to already fragile populations.
There are 836 whooping cranes left in the world, according to ICF, including 543 in a flock that migrates from Canada to Texas each year and 76 in the eastern migratory flock centered in Wisconsin.
The ICF is concerned about the global re-emergence of avian influenza this winter, its impact on threatened East Asian cranes and the threat to whoopers.
“The outbreaks are like wildfires,” Hartup said. “These are little super-spreader events. They are virtually impossible to predict or prevent in the wild.”
In addition to the common crane deaths in Israel, the virus has killed hooded, white-naped and possibly red-crowned cranes in Japan this winter, according to the ICF.
The disease spreads when infected birds shed the virus in their saliva, nasal secretions and feces, according to the Centers for Disease Control and Prevention. Susceptible birds become infected when they have contact with the virus as it is shed by infected birds or surfaces contaminated with the virus.
Some birds carry the virus without getting sick. In other cases it causes mass mortality events.
With HPAI circulating, Hartup said whooping cranes would face additional risk this year during migration at a stopover site in Saskatchewan and at roosting locations in Texas, both spots where they will undoubtedly be in close proximity with waterfowl.
So far the good news is that no whooping crane has died from or been detected with the virus. Several wild whooping crane chicks were tested this year in Canada; all were negative, according to Hartup.
Whoopers may also be less likely to get the disease because of their standard behaviors. They don’t roost in large flocks, for example.
But ICF staff is on heightened alert this winter and will remain so through next year.
“This outbreak is unprecedented,” Hartup said. “It’s also been extremely persistent. As I look at the impact of this disease on wild birds, not just cranes, it’s been hugely significant in terms of the rapidity and spread and number of birds affected. For the sake of all bird species, we’re hopeful the coming months will bring better news.”