Moose count coming in--slowly
Researchers have gathered the first results from the $1.2 million moose study that began this year in Lake and Cook counties. Six of the moose in the study have died and crews have responded quickly to determine the cause of death for these animals.
Minnesota wildlife researchers trapped 111 moose in January and February and placed GPS trackers and transmitters on the big animals. It's the most elaborate effort yet to find out what's causing the rapid decline of the state's moose population.
The goal is to get crews to dead moose quickly to retrieve key organs and tissue to find out what has killed the animals. Until now, by the time researchers found the dead moose, they were often too badly decomposed to be of much use, or had been partially eaten by wolves.
Of the six dead, four are listed as having perished from capture-related mortality, meaning the stress of being tranquilized and collared led to complications and death. That rate of about 3.6 percent is average for capture/collaring projects, said Erika Butler, Minnesota Department of Natural Resources veterinarian in charge of the moose mortality project.
Lower body fat
Of the two animals that died from other causes, both appear to be victims of wolf attacks. One had been mostly eaten, and the other had injuries from a wolf attack but had not been eaten. From a post-mortem investigation at the scene, it appears wolves got the big cow's calf and then left the area before the cow died, Butler said.
"She died from secondary issues after being wounded by wolves. ... It was pretty cool how (the crews) went in there and figured out what happened," Butler said.
While wolves were the ultimate cause of death for those moose, Butler said both of them, and even some of the moose that died from capture-related stress, had lower-than-usual body fat in what has been a fairly normal, if not mild, winter in moose country.
"When we are capturing them in January, that's early enough in winter that they should still have some good body fat, and three of these didn't. That's not normal," Butler said.
A reduction in nutrition, possibly from warm weather in the summer when moose are too hot to eat, or from habitat issues, is one theory why moose are having problems making it through winter.
Getting in fast
It's the quick-response team's job to get to the newly dead moose within about 24 hours, especially to retrieve the brain, eyes, liver, heart, kidneys and spleen. Moose are so big and retain heat so well that their organs begin to decompose after just 24 hours.
The expensive high-tech collar systems are sending satellite messages when a moose stops moving for six hours, about twice as long as the usual moose nap. Once located by ground crews, the 700-pound animals can be hauled into a lab or, if they are too remote, much of the work can be done in the field, with samples taken for complex lab analysis later.
The DNR has made saving the moose among its top wildlife management issues, and last year added moose to its list of troubled species as a "species of concern." Just last month the state's limited fall moose hunt, scaled back in recent years, was canceled altogether for 2013 and probably will never be held again.
According to aerial surveys, the Northeastern Minnesota moose population dropped 35 percent from last winter to this winter -- from an estimated 4,230 in 2012 to 2,760 this January. That one-year decline was more than double the average drop in recent years of 15 percent. The population was as high as 8,800 in 2006.