A calf that keeled over in an Anchorage neighborhood last month may be the first documented case in Alaska of a moose dying from cyanide poisoning, according to the state Department of Fish and Game.
The animal suffered a disorienting death but created a boon for scientists trying to understand what kills moose, in urban settings and in the wild.
The source of the cyanide, the scientists said, was probably an ornamental tree or plant, perhaps a chokecherry, based on an initial examination of the berries, seeds, leaves and stems found in the calf's stomachs.
Such trees, including the popular May Day tree, are known to produce cyanide, a poison that starves cells of oxygen.
"We know the animal died from something that released cyanide," said Kimberlee Beckmen, a veterinary pathologist with Fish and Game in Fairbanks. The calf's liver and rumen, which is the first of its four stomachs, contained "significant levels" of the poison, she said.
"There's no survivable way to have this level of cyanide," Beckmen said.
Results of tests on the plant material found within the animal have yet to come back from an Outside lab, so the specific source of the poison has not been identified, she said.
Kathy Burek, a private veterinary pathologist who performed the necropsy on the moose in the bed of a pickup in the driveway of her Eagle River home, said the cyanide certainly contributed to the animal's death. But other factors also could have been involved, she said.
The calf, a female less than a year old, was thin, and its rumen was "abnormally distended ... just packed full of dryish feed material," Burek said. That included "grass and what looked like hay or straw, and a large number of berries." Clearly, she said, the stomach was not emptying.
Moose cannot easily digest hay in winter, said Beckmen.
"If the cyanide (tests) came back negative, I would be perfectly happy saying this animal died because it was eating material that it couldn't digest, and it became impacted." Burek said.
"We know it had cyanide," said Beckmen. "Unless somebody fed it a fungicide, it has to have come from a plant. We don't know how long (the poison) was in the animal, but it should have died very quickly."
Cyanide dissipates rapidly, she said. The calf was necropsied within four hours of death. Had 12 more hours passed, no cyanide would have been found, according to Beckmen.
No one is known to have seen what the moose ate before it died. But Cyndy Kroon, who lives a few blocks from Dimond High School, saw the calf from her kitchen window, over the last 45 minutes of its life on Jan. 13.
Its legs were tucked under and its head faced her neighbor's daylight-basement window a few feet away.
"It was really odd," Kroon said. "As I was watching her, every few seconds her head would shake, like a shiver."
And "like slow motion ... she slowly went backward as if she were going to sit on her bottom, and her bottom went into the window ... like she had done it on purpose," Kroon said.
The calf flailed until it freed itself from the broken window, then lay on its side on the ground, Kroon said. It continued to flail while she called the police.
Police arrived in less than 15 minutes, but the moose was dead by then, Kroon said.
Cyanide has been suspected of causing other moose deaths in Alaska, but none so well confirmed, according to Fish and Game. The agency has rarely been able to have animals necropsied so soon after death, Beckmen said.
The berries found in its system were dark, reddish-orange or nearly maroon, Burek said. Each berry contained multiple seeds, about the size of raspberry seeds, and had a long stem. Based on that, Burek said, she ruled out mountain ash, a moose favorite.
Chokecherries contain high concentrations of cyanide, said Bob Wheeler, a forestry specialist with the University of Alaska's Cooperative Extension Service in Fairbanks. It would take only 200 mg -- a tiny amount -- of well-chewed chokecherry material to kill a 100-pound animal, Wheeler said.
Chokecherries are part of the Prunus genus, whose seeds and stems produce cyanide. Their toxicity rises when the tree is frozen, Beckmen said. "So it's only a problem in winter."
If the berries found in the moose do contain multiple seeds, they probably are not Prunus, said Julie Riley, a horticulturalist with the Cooperative Extension Service in Anchorage.
"The Prunus species have one seed" to a berry, Riley said.
Kroon said she has a May Day tree in her front yard, but it's obstructed by a large berm where her husband plows the snow from their driveway.
"I rarely see moose around that tree, although Rick (Sinnott) said it looked like something could have been eating on the branches that stick out," Kroon said.
Daily News reporter Peter Porco can be reached at firstname.lastname@example.org or 257-4582.