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Beaver deaths still a mystery

This year’s litter of Martinez beaver kits, like these two photographed near Alhambra Creek in 2010, have died from unknown causes in recent months. One kit hasn’t been spotted in some time, but the bodies of several others have been recovered. Certain poisons and environmental causes have been ruled out. (CHERYL REYNOLDS / Worth a Dam)
This year’s litter of Martinez beaver kits, like these two photographed near Alhambra Creek in 2010, have died from unknown causes in recent months. One kit hasn’t been spotted in some time, but the bodies of several others have been recovered. Certain poisons and environmental causes have been ruled out. (CHERYL REYNOLDS / Worth a Dam)

By DONNA BETH WEILENMAN
Martinez Tribune

MARTINEZ, Calif. – The family of beavers that live in Alhambra Creek apparently has lost this year’s litter as well as one born last year, but the cause of the deaths remain a mystery, said Heidi Perryman, president of Worth a Dam, and Conrad Jones, California Department of Fish and Wildlife senior environmental scientist and supervisor.

The kits were about 10 weeks old when they started dying, Perryman said. By the time the first dead kit was found in early July, its corpse was too badly decomposed for a necropsy, Perryman said.

But the plight of the baby beavers came to public attention when someone spotted another kit that was alive but obviously suffering. The animal was found near Marina Vista and Alhambra Avenue where Worth a Dam has its annual Beaver Festival.

The little creature, weighing a little less than five pounds, was taken to Lindsay Wildlife Museum’s hospital in Walnut Creek, but was too ill to recover and was euthanized, Perryman said. The beaver underwent a necropsy. It’s weight was normal for its age.

Since then, the body of the 45-pound, 15-month-old older sibling to the kits also was found, as was that of a third kit. The fourth kit born this year hasn’t been seen in some time, Perryman said.

What is frustrating both Perryman and Jones is tests aren’t pointing to any particular reason for the deaths.

“They were all healthy-looking guys,” she said.

Necropsies on the bodies fresh enough to be examined were tested for toxins and parasites, Jones said. The animals also were examined for trauma as well as sodium, in case the drought had caused so much salt water intrusion that it threatened the beavers.

“We sent water samples with the carcasses,” Perryman said. She had hoped tests would show if the creek had been contaminated by poisons used on rodents, particularly rat poison, or if someone had tainted it with antifreeze or other chemicals.

But the results on both the water and the animals’ tissues all were in normal parameters, Jones said.

“We found evidence of illegal feeding,” Jones said. The necropsies revealed domestic apples, including their plastic labels, had been eaten by the beavers, but Jones doesn’t consider that to be a contributor to their deaths.

Nor were there lesions that would indicate a bacterial infection had killed the animals, he said. Rabies also has been ruled out.

There’s no indication that remains from any illegal drug use, or that accidental contamination with marijuana could be the cause. Although some San Francisco Bay Area veterinarians began reporting last year they were seeing an increase in the cases of marijuana poisoning in dogs and other pets, Jones said that doesn’t appear to be the case for Martinez’s beavers.

He said he has shared his findings with the University of California, Davis, but no one is closer to pinning down the cause of the beavers’ deaths.

“There’s nothing we could point to,” Perryman said. “They’re concerned there’s no clear cause.”

The beavers first were seen in Alhambra Creek in 2006, Perryman said. At first, their presence became controversial, with some authorities advocating trapping the animals. Some suggested removing them; others suggested they be killed. Perryman and others formed Worth a Dam to counter those proposals.

Since then, many residents have considered the beavers a source of pride and a city mascot.

Perryman said Worth a Dam had considered capturing an animal to obtain a blood test, but learned that would only be helpful if the necropsies had put scientists on the track of whatever is causing the deaths.

Whatever is affecting the beavers doesn’t seem to be impacting the creek’s fish or turtles, Perryman said. So far, no one has found any fish kills or dead turtles.

Another problem is that some of the carcasses had begun to decay, and as the bodies decompose, they lose some clues as to the cause of the deaths.

The dead beavers may have been found late because they died someplace where the bodies were shielded from view, such as in their lodge. Only when creek water moved the bodies into an open area were they spotted, Perryman said.

Should someone find a beaver’s body, the best tactic is to put it into a refrigerator, Jones said. But beavers can grow so large, they won’t fit in a refrigerator.

Jones suggested people put the carcass in an old cooler and keep it chilled until a Department of Fish and Wildlife volunteer can retrieve it.

Both Jones and Perryman said people should not feed the remaining beavers.

Perryman said people often feed apples and carrots to the animals. “We’re asking people not to feed the beavers – not at this time,” she said.

It’s illegal to feed big game animals, and it isn’t a good idea to feed any wildlife, Jones said. No matter the species, the animals begin associating people with food.

“If they see an easy meal ticket, they will get assertive, and even aggressive,” he said. That can result in confrontations with people. “Ultimately, the wildlife suffers.”

As for the surviving beavers, Jones said, “We hope for the best.”

Perryman said her advocacy organization, Worth a Dam, and other volunteers are walking the length of Alhambra Creek from Ward Street to the court area not far from where the animals’ lodge has been built. They make the trip twice a day, she said.

They’ve seen the parent beavers and two of their two-year-old offspring that soon will be ready to go off on their own and seek homes elsewhere, a common beaver practice.

Anyone who sees a sickly or injured beaver or finds a body may notify Worth a Dam at mtzbeavers@gmail.com. Should anyone find a body, Jones said the person may call the California Department of Fish and Wildlife at (707) 944-5500.

Meanwhile, Perryman and members of her organization remain worried.

“I don’t know how well they’ll weather this,” she said. “I hope by the time we get this solved we have some beavers left.”

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