PORTSMOUTH, Va. - Wildlife biologists are baffled and intrigued by two incidents captured on videotape at a bald eagle nest in Portsmouth - an eagle parent attacks, kills, then eats its two scrawny young.
"We've never seen anything like this," said Bryan Watts, director of the Center for Conservation Biology at the College of William and Mary, which was monitoring the nest with a 24-hour camera.
Watts and colleague Mitchell Byrd, a renowned eagle expert in Virginia, contacted other scientists after viewing the footage and found that cannibalism among the nation's signature bird has never been documented or even suspected.
'I was stunned'
"I was stunned when I heard about it," said Craig Koppie, an endangered species biologist with the U.S. Fish and Wildlife Service who keeps tabs on bald eagles in Virginia, Maryland and Delaware. "It's very weird, and obviously worth additional study."
According to several experts, the footage from a nest at the Hoffler Creek Wildlife Refuge in Portsmouth spurs numerous questions about animal behavior and the bald eagle, a federally protected species. Among them: Does cannibalism occur more often in nature than scientists believe? Were the parents of this troubled eagle brood just practicing euthanasia? Was pollution or contamination a factor?
Watts said he and a graduate student monitoring a handful of eagle nests on the lower James River will sit down next month and consider these issues. They likely will write a report and suggest additional avenues of research.
The incidents occurred April 9 and 10. Randi Strutton, executive director of the Hoffler Creek Wildlife Foundation, which runs the refuge, witnessed one of the attacks as she was watching live footage of the birds on closed-circuit television.
'It was just awful'
The father eagle "grabs the baby with his feet, drags it to the edge of the nest, holds it down and uses his beak to tear it to shreds," Strutton said. "It was just awful. We couldn't believe what we were seeing."
The adult male ate the carcass in about five minutes. But he would not share any meat with the other chick, which had waddled over, thinking it was mealtime.
The next day, the father returned to the nest, again without food, and attacked the remaining chick the same way. Since then, the two adults have left the nest but still hang around the refuge, Strutton said.
Bald eagles have successfully mated the past two springs at Hoffler Creek. Three chicks were produced last season, a bumper crop; two were raised the previous season.
This year, though, trouble has followed the birds.
After William and Mary researchers installed monitoring equipment this winter, burglars broke into the refuge and stole an expensive time-lapse video recorder, temporarily shelving the research project.
After the birds mated and the eggs were laid - again, there were three - Strutton noticed that the adult male did not come around, nor did he bring food. "He was like an absentee dad," she said.
The youngest of the chicks died within days, probably from malnutrition. The siblings were fragile, too, small and skinny for their age.
Watts said this "energy-deficient" setting, with little food coming in for the adults and babies, might be the main reason for the attacks.
What's puzzling, Watts said, is why the adults didn't simply abandon the nest, which eagles are known to do when faced with a doomed brood."Who knows? Maybe they do this more than we ever thought," he said.