Minnesota moose calf study works through setbacks
Minnesota wildlife researchers will keep trying to collar and study newborn moose calves in 2015 even though things haven’t gone well during the first two years of the effort.
Last May and June, researchers put GPS collars on 25 moose calves just hours after they were born. But 19 of the 25 calves either were abandoned by their mothers and had to be rescued, or their collars fell off or stopped working, leaving only six calves to be studied.
By August, all six had been eaten by predators, mostly wolves.
“It’s frustrating. But we need to persevere,” said Glenn DelGiudice, lead moose researcher for the Minnesota Department of Natural Resources.
Moose experts say more information is needed on how many calves are dying, and how they are dying, to accompany ongoing research on adult moose as Northeastern Minnesota’s moose population continues to dwindle.
The results of an aerial survey in January showed lower overall moose numbers, with more than a 60 percent drop since 2006. Researchers say there appear to be problems both with adult and calf moose. Disease, parasites, climate, habitat and predators are factors, although specific causes of the decline still aren’t clear.
The disappointing 2014 calf study was even less successful than 2013, when 49 calves were collared and 15 either lost their collars or were abandoned by their mothers. Many of the 2013 abandoned calves perished.
Last summer most of the abandoned calves were rescued and given to the Minnesota Zoo. Both years saw public complaints that the research wasn’t worth the loss of calves.
“We were at a point last summer when we almost shut it down. We were just getting hammered by some of the public and some legislators” because of the high rate of abandonment, DelGiudice said.
But DelGiudice, who spoke last week at a wildlife research symposium specifically on the problem of “capture-related mortality” in calf moose, said he and other researchers began to “figure out what works” by the end of last summer’s collaring effort.
Plans for 2015 and 2016 The calf study has full funding for this year and DelGiudice said — while knocking on a wooden desk — that he expects it to continue into at least 2016. He said he expects to capture 50 calves each in 2015 and 2016 to get a larger sample size to determine what is naturally killing the young moose.
One major problem in the past was collars that didn’t fit well, fell off or stopped working. The researchers worked with the GPS manufacturers, including tests on cattle, to fix those problems for 2015.
“We think we have most of the bugs worked out,” DelGiudice said, noting that his is the first study anywhere in which newborn ungulates have been fitted with GPS collars that offer real-time data.
Researchers now can find a dead calf within hours of when it stops moving. (The researchers are able to find a newborn calf in the first place because the pregnant cow already has been fitted with a GPS collar. When she stops moving to give birth, researchers wait a day or so and swoop in.)
In the past, when VHF-radio collars were used, researchers never knew what happened to the cow-calf relationship. If they came back days later and found a wolf-killed calf, they listed it as a predator kill — when in fact it may have been caused by the cow leaving after the capture.
No previous research had ever noted the high level of abandonment the Minnesota researchers are seeing. Now, DelGiudice is using the sour results as a teaching moment .
Capture-related mortality “is ubiquitous and it’s underestimated” in this kind of wildlife study, he told the symposium. “We were the first ones to do this, ever, anywhere, and we knew there were going to be issues. … We just didn’t expect them to be like this. We didn’t see it coming.”
Instead of using a helicopter, as crews did in 2014 and as has been done successfully in Alaska, crews last year walked into calf birthing sites. But they still had a problem with cows abandoning calves until they limited their visits to just two people and spent less than 10 minutes with the animals.
The goal is to get in and out as fast as possible. The only data they record now is the sex of the calf.
“The problem has never been the calf. They have no issue with the capture. They aren’t tranquilized, and they don’t even try to run,” DelGiudice said. “The problem has always been the cow and whether she will come back and stay with the calf.”
Some cows came back and left repeated times, only to leave for good several days after the collaring. Researchers have no idea why some cows leave and some cows stay with their young. Few patterns have emerged.
DelGiudice said this year’s effort, which will start when the first calves are born in early May, will include two teams of two people, highly trained and experienced, to work fast with as little disturbance as possible.The goal is to get 50 collars on calves so they can be tracked past the first few days of life.
Then, it’s up to the calf.
So far, they haven’t been doing well.
Most calves dying young Of the calves that have survived being collared, 75 percent have died before their first birthday, said William Severud, a University of Minnesota researcher who is crunching the numbers for the calf study.
The sample size still is small, only 41 calves in two seasons, but patterns already are emerging, Severud said.
Wolves have killed 69 percent of the collared calves, with bears a distant 17 percent. Most of the calves died within 30 days of being born. Other causes — such as disease, starvation, vehicles or natural abandonment — each accounted for just a few deaths each, Severud noted.
Severud said the GPS collars allow researchers to get to a dead calf quickly to conduct their “crime scene investigation.”
‘“The difference between a bear kill and wolf kill is pretty clear,” Severud said. Bears usually only eat part of the carcass and leave some for later. “When there’s a wolf kill, there’s usually very little evidence left” except scat.
Severud noted that the research has found the average Minnesota moose calf is born on May 14 and weighs 35.5 pounds.
The researchers spoke at last week’s joint annual meeting of the Minnesota and Wisconsin chapters of the Wildlife Society, held in Duluth. More than 400 people attended the three-day event — mostly wildlife researchers for state, federal and tribal wildlife management agencies and university research centers. Many graduate and undergraduate wildlife biology students also attended the event.