Die-off of Eastern Geese Stumps Biologists

Hundreds of Atlantic brant geese began turning up dead in the Edwin B. Forsythe National Wildlife Refuge last November, and not all died quietly.

Some fell from the sky in mid-flight, stricken by a mysterious ailment whose origin continues to stump wildlife biologists and disease experts alike.

One motorist reported seeing a bird drop suddenly from above, floundering in his path before crashing into a guardrail. The carcasses of others were found in this sprawling wildlife refuge outside Atlantic City and on the beaches of the neighboring island of Brigantine.

The die-off is puzzling: The dead geese appear perfectly healthy otherwise, with plenty of body fat and no signs of trauma. Laboratory examinations show no evidence of West Nile virus, avian cholera, pesticide poisoning or any other common killer of waterfowl.

Strangest of all, the brant seem to be alone. No other bird, fish or mammal in the coastal salt marshes is being stricken by whatever it is that killed about 700 brant in November.

“I’ve been studying waterfowl since I got out of school 20 years ago,” said Tracy Casselman, a U.S. Fish and Wildlife official at Forsythe who has disposed of some of the dead birds. “I’ve seen some small botulism die-offs but never a single species like this. That’s the biggest mystery.”

In the months since, the mystery has only deepened. Flocks of healthy brant still swim and fly in the refuge, in its salt marshes and in nearby Lakes Bay and Reeds Bay--all apparently unaffected.

But a second die-off in mid-January left about 1,000 brant dead, most of them on Brigantine. Necropsies and laboratory testing of tissue samples from the birds showed heart hemorrhaging, spotted livers and fluid in the lungs. During the last week of January, about 20 more dead brant were found in and around the refuge.

Experts at the U.S. Geological Survey’s National Wildlife Health Center in Madison, Wis., are trying to pinpoint the cause. And other agencies are being called in to help.

The National Marine Fisheries Service and the National Oceanic and Atmospheric Administration are being consulted in a bid to determine whether algae blooms or biotoxins could be killing the geese, which breed in the Canadian Arctic and spend winters in the estuaries and back bays of New Jersey and other Eastern states.

Young and old, male and female are being stricken, but only in New Jersey. Wildlife biologists along the Atlantic coast in Maryland, Virginia and elsewhere have seen no such deaths.

“We’ve talked to biologists from Canada to South Carolina, and there’s no problem outside this area,” Casselman said.

Brant die-offs have occurred before, but not like this. In the 1980s there were instances in which up to 60 brant perished, but post-mortem examinations identified pesticides as the cause; the birds ingested it while grazing on golf courses.

In the 1970s, a similar number starved to death during one year in which the availability of eelgrass--one of their principal sources of food--was down.

But this is different, according to Kimberli Miller, a wildlife disease specialist at the National Wildlife Health Center.

“An environmental cause? That’s one of the things we’re trying to figure out. Is there something about that particular site? We’re trying to look at what similarities and differences there are between where the brant are dying and where they’re not.

“For disease to occur, you need three things: an acceptable host, a disease agent and an environment suitable to both of them. We’re trying to sort out what the factors are that are associated with this die-off, looking at air temperatures, water quality, that type of thing.

“Typically, if it’s something like a pollutant, you’d see a variety of birds and mammals and fish affected, as opposed to one little species,” Miller said.

New Jersey’s brant-hunting season, which ran from Nov. 19 to Jan. 9, was cut short because of the first die-off. Though it wasn’t canceled outright, the state warned hunters not to handle or eat the birds.

The human health risk posed by the dead birds isn’t known. But officials are warning people here not to handle--or even let their dogs paw--dead brant.

The state Department of Environmental Protection has no plans to begin air testing or water sampling yet, mainly because there appears to be no public health threat, spokeswoman Sharon Southard said.

“We’re working with Fish and Wildlife to continue with the testing. They need to do further testing before we make a decision on all of that,” she said.

The puzzle is particularly frustrating to Miller, Casselman and others involved in the investigation. Although they don’t want another die-off, they say they might have to wait for one to progress any further.

“I sit there and ponder--on my way back and forth to work, in the shower in the morning, wondering what this is,” Casselman said. “We’ve got the best researchers in the nation working on this, and now we have people overseas too. It just defies all the traditional logic.”

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U.S. Geological Survey: https://www.usgs.gov

U.S. Fish and Wildlife Service: https://www.fws.gov/