FAIRBANKS -- When Tina Buxbaum saw a cow moose walk through her yard with three moose calves in tow earlier this summer, just a few miles north of Fairbanks, she didn't give it much thought.

"Two years ago she raised one calf, last year she raised two, and this year she has three," Buxbaum said.

Whether they are all hers is a question that has stirred debate among local moose experts.

Twins are rare in most moose populations, and triplets are almost unheard of. In addition, Game Management Unit 20B, which includes Fairbanks, has one of the lowest twinning rates in the state.

On top of that, moose have been known to "adopt" abandoned calves and raise them as their own, even if they already have one, or maybe two, calves.

Twice in recent years cow moose in Delta Junction have been photographed with four calves, but in both cases, biologists said it was almost certain that the cow had adopted a pair of twins somewhere along the line because quadruplets have never been documented in moose and the calves appeared to be two different sizes.

"Cows get killed all the time on the (Fairbanks) road system and there are newborn calves looking around for mothers," said moose research biologist Rod Boertje with the Alaska Department of Fish and Game in Fairbanks. "It might just have to bawl a little bit and a cow comes over and adopts it.

"Moose are a species that are more apt to adopt, not like caribou," Boertje said. "If it was a caribou, it'd probably stomp the little critter to death."

Boertje has seen only one set of triplets in the almost 30 years he has studied moose and caribou. That was back in 1985 on the Salchaket Slough, southwest of Fairbanks. It would be "incredibly unusual" for a cow moose in Fairbanks to have triplets, he said.

Even when he saw a picture Buxbaum took of the four moose in her yard, Boertje wasn't convinced.

"If it did have triplets it's getting some supplemental feed somewhere, I'll guarantee it," he said.

As is the case with wildlife in general, reproduction in moose is directly related to body condition. The better physical condition a cow is in, the better chance it will produce a calf or calves. A cow that is not in good health won't get pregnant, much less produce twins.

Physical condition is based mainly on food availability. While plenty of food is to be had around Fairbanks, a lot of moose are also competing for it. The moose population around Fairbanks is already showing signs of nutritional stress, based on the low twinning rate, said Tom Seaton, assistant area biologist at Fish and Game in Fairbanks.

That helps explain why Seaton was immediately skeptical about the possibility of a cow moose in Fairbanks giving birth to triplets.

Looking at Buxbaum's photo only reinforced that opinion. Two of the young moose look smaller than the third, Seaton said. The cow might have found the bigger calf abandoned or it could have found a pair of abandoned twins, he speculated.

Though the odds are stacked against it, Seaton said there's always a chance they are true triplets.

"Freak things can happen," he said. "It's possible, but it's highly improbable."

A countering opinion was offered by Fairbanks area biologist Don Young. After looking at the same picture Boertje saw, Young said the calves could be triplets. To his eye, they are all about the same size, and they all have light brown legs, a sign they are the same age.

"My take on it is that it's a cow with triplets," Young said. "It's certainly possible."

That being said, if the cow did have triplets it probably had some help in the form of someone feeding it during the winter. It's not out of the realm of possibility. Lots of people around Fairbanks feed moose in the winter, even though it's illegal and can be harmful to the moose or the feeder, Young said.

"Without some kind of supplemental feed the likelihood of having triplets is very low," he said. "I think it's more likely in (Fairbanks) that a cow moose could get supplemental feed."

Buxbaum thinks it's the same cow moose that has been hanging around the neighborhood for the past few years. Unlike other moose that wander into the neighborhood, the mother moose ignores her neighbor's barking dog as if she's become conditioned to it.

If the same cow had twins last year, the chances of it having triplets, or even twins, this year is almost impossible to comprehend, Boertje said.

"Generally moose don't produce twins and then triplets," he said. "It's too much of an energy budget demand. The energy demands are really high for lactating and giving birth."

Even in Togiak National Wildlife Refuge in Southwest Alaska, which has the highest twinning rates in the state at more than 60 percent, refuge biologist Andy Aderman said triplets are rare.

Since he began putting radio collars on cow moose to track twinning rates in 1998, Aderman said, he has documented the births to 249 radio-collared cows and only three had triplets.

"They're fairly uncommon, even out here," said Aderman.

All sightings were in the spring, increasing the chances they were actual triplets and not the result of adoption, he said.

Whether the calves are actually triplets or stepsiblings doesn't matter to Buxbaum, but a cow with three calves was a rare sight.