Wildlife deaths odd?
Mass casualties aren’t uncommon, experts say.
It’s death on a wide scale, biblical-type stuff: Millions of spot fish died last week in the Chesapeake Bay; red-winged blackbirds tumbled from the skies by the thousands in Arkansas and Kentucky over the holidays; and tens of thousands of pogies, drum fish, crab and shrimp went belly up in the summer in a Louisiana bayou.
For an explanation of these mysterious events, some have turned to Scripture or to the Mayan calendar, which suggests the world will end in 2012. But wildlife experts say these massive wildlife kills were not the result of a man-made disaster or a spooky sign of the apocalypse.
They happen in nature all the time.
In Arkansas, state and federal biologists say they think that sleeping birds probably heard a loud boom in the night and freaked out. In Louisiana, low-oxygen ocean water regularly creeps into the higher-oxygen bayou and suffocates fish and crustaceans.
Maryland wildlife biologists are still investigating the deaths of 2 million spot and some croaker, also known as drum fish. But they have a theory: These fish are particularly vulnerable to cold and were killed when water temperatures dropped suddenly and sharply in late December. Most of the dead were juveniles.
“It’s colder than it’s been in 25 years,” said Dawn Stoltzfus, a spokeswoman for the Maryland Department of the Environment. That’s terrible news for the spot. In 1976, 15 million were killed during a cold snap.
The department’s phones started ringing with reports of dead fish two days before the new year and haven’t stopped. “ The first ones we heard of were in Calvert County. Then some big ones over the last weekend in Annapolis and Kent Island. It could be over. It’s too early to speculate,” Stoltzfus said.
The state doesn’t bother to clean up. Nature takes its course when fish wash up on shore, which began to happen Thursday, or birds pluck them from the water. “ The best thing to do if you come across them is to not touch them, and bury them,” Stoltzfus said, in advice to bayside residents.
In Arkansas, “5,000 birds falling dead in people’s yards is just weird,” said Kevin McGowan, an ornithologist at the Cornell Lab of Ornithology. “But the question is, has this happened before?”
The answer is yes, “ but probably in a cornfield. And foxes ate them all,” McGowan said.
“All birds die,” he continued. “You rarely see them for several reasons. They’re usually alone. They’re often eaten by the thing that killed them, or they go to some sheltered place to die. You rarely see dead birds until they whack into your window.”
When birds fall out the sky and fish float to the surface as if in a nightmare, people reach for an explanation. At least one Internet blogger cited the Mayan calendar, and another turned to the doomsday prophecies of Nostradamus.
Others believe humans are responsible. People have been known to throw poisonous food to birds, and workers have illegally dumped pesticides into storm sewers, such as in the District in 2000, which led to the largest recorded fish kill in Rock Creek Park. A Silver Spring extermination company was charged in the crime.
Large man-made disasters have taken an enormous toll, such as the Exxon Valdez oil spill in Alaska’s Prince William Sound and the BP oil spill in the Gulf of Mexico.
But natural diseases such as avian botulism and cholera stalk birds as they nest in enormous colonies, killing thousands. Bacteria that lurk near fish and amphibians often take lives.
The red-winged blackbirds in Arkansas were probably asleep when they heard a loud boom from a high-intensity firework shrieking through their tree roost. As it happens in such cases, the birds went nuts, said Carol Meteyer, a veterinary pathologist for the National Wildlife Health Center, a division of the U.S. Geological Service.
“ They fly disoriented and crash,” Meteyer said. “Bird reactions are endemic. One bird reacts, and the other freaks out. And on it goes. I wouldn’t say it happens all the time. I’ve been here 20 years. You see them occur once in 10 years, but they happen.”
Several hundred red-winged blackbirds were killed when they flew into power lines in Louisiana this month, Meteyer said. About the same time, Kentucky game officials said several hundred dead red-winged blackbirds, grackles, starlings and a few robins were scattered about in Murray, Ky., near the campus of Murray State University. Tests showed no diseases or toxins, said Mark Marraccini, a spokesman for the Kentucky Department of Fish and Wildlife Resources.
In March 1996, a blizzard hit the Platte River in Nebraska as more than half a million sandhill cranes nested at the peak of their migration. In the biggest known kill of the cranes, birds driven by high winds flew beak-first into trees and buildings during a failed attempt to outrace the blizzard. More than 2,000 died.
On the ocean, “ there are wrecks of pelagic birds, birds that never come to shore,” Meteyer said. “ Thousands upon thousands can die because of no food source. They have no body fat, no disease. Starvation happens out there.” She added that sometimes the populations of fish they feed on go too deep because the surface water is too hot.
The difference between most wildlife kills and the deaths in the Chesapeake and Arkansas, Louisiana and Kentucky is that people were not aware that they happened, Meteyer said. “ The difference is the media. They are getting more notoriety. But I don’t think they are more frequent than in the past,” she said.
The Louisiana kill was hard to ignore. In Bayou Chaland in Plaquemines Parish, tens of thousands of silvery fish bellies shimmered under the sun. Photographs of the fish clogging a corner of the bayou in the aftermath of the BP oil spill were dramatic.
But the event wasn’t connected to the spill and was not unusual. Robert Barham, secretary of the state Department of Wildlife and Fisheries, said a drop in dissolved oxygen levels caused either by die-offs of microorganisms or a sudden upwelling of low-oxygen water from the deep sea probably killed the fish.
It’s happened in the past, long before the spill off Louisiana’s gulf coast. In some areas, low-oxygen pockets have caused socalled “jubilees,” where blue crabs haul themselves suddenly out of suffocating water.
“It is not an unexpected event,” Barham said.
Dead fish, mostly spot and a few small croaker, washed ashore this month at Northwest Creek on Kent Island in Stevensville.