ADF&G biologists first to establish daily, seasonal variation of moose body temperature

Moose are well-adapted to handle Alaskan winters, but warming temperatures have lead biologists to research how a warmer climate will impact animals.

Biologist with the Alaska Department of Fish & Game have now laid the groundwork for how future studies will measure the impact of warming conditions on moose.

Researchers at the Kenai Moose Research Center used a new method of tracking temperature in moose to document the daily and season fluctuation in moose body temperature.

A device called a vaginal implant transmitter is commonly used to detect when and where a cow gives birth. The ADF&G researchers adapted the tool to include a thermometer that transmitted the animal's core body temperature every five minutes for up to a year.

"We basically started this body temperature stuff to look at how a moose responds to warm ambient conditions," said Dan Thompson, a wildlife biologist at the Kenai Moose Research Center. "There's been some research done in the 80s that suggested that they are very heat-sensitive. However, some of our observations here on site suggest otherwise, so we wanted to actually measure a physiological metric that would actually see if they are becoming warm during warm conditions."

The researchers implanted the transmitters in both wild animals that were chemically immobilized and in captive research animals.

"We know what's going on when an animal - when we have it immobilized by taking their temperature, but once we release it and let it go, we don't know what's going on. So these devices allow us to continually record their body temperature after they've been released," Thompson said.

The agencies was the first to both use vaginal implant transmitters in wild ungulates and establish the daily and seasonal variation of body temperature, Thompson said.

In addition to the core body temperature data on wild moose, animals that live in one-square-mile pens at the Kenai Moose Research Center allowed the biologists to closely monitor how they respond to warm ambient conditions.

"We could put a Polar heart rate belt on. Just like you'd put one on to go to the gym, they make some for horses that we put on our animals. So we can get heart rate, respiration rates, and also use forward-looking infrared camera to get skin temperature on them," Thompson said. "As well as a very fine wire thermistor that would actually stick on the end of a tent pole, and when these guys are laying down I could stick it up in their nostril and that will give the temperature of the air being exhaled out of their lungs."

Researchers looked at those metrics in conjunction with core body temperature to see how the animals respond to various conditions.

"We can look at all these other mechanism that they're using to moderate their body temperature, whether that's increased breathing, increased heart rate, increased skin temperature - so they're pushing more blood to the extremities, or more energy comes out of every time they exhale a breath," Thompson said. "So we've been able to document that in tandem with these temperature loggers in the animals."

In their study published in the Journal of Mammalogy, the researchers write that by understanding the daily fluctuation of body temperature in moose, future studies will be able to more accurately discern when a moose is responding to warm environmental temperatures.