A smaller part of a much larger study into what is killing Minnesota’s moose involves the capture and collaring of moose calves when they are at least 36 hours old. Last year 11 of 49 captured and GPScollared calves died soon after the study began because of the trauma of being collared. It was the first year the Minnesota Department of Natural Resources (DNR) conducted a calf morbidity study, and things went wrong from the beginning.
This year, however, the DNR changed the way they have gone about their business and the results are dramatically different.
A new, scaled down two-tiered approach to collaring moose calves has worked very well, with only one calf dying after being abandoned by its mother after capture, said Glenn DelGiudice, moose project leader for the DNR.
By February 2014 last year there were only eight calves left to study. The DNR realized that the collars were too tight and caught and released the remainder, ending the study several months short of its intended goal.
“This year we began ground capture operations on May 8, the same as last year,” DelGiudice said, but no helicopters were used this time.
“Without the helicopter, the captures required much greater physical effort, but they’ve been going smoothly,” said DelGiudice.
And DelGiudice said, researchers had dramatically modified the capture approach to significantly reduce the risk of abandonment. “We limited our capture teams to two people and the only field objective was to fit the GPS collar, which requires less than 10 seconds rather than the previous four minutes.
GPS collars were modified to better fit the calves. After one year the collars will drop off.
While the calves were being collared their mothers’ behavior ranged from “mildly to modestly aggressive (best from a calf-protection perspective),” DelGiudice said.
As of May 15, 12 calves of nine dams were captured, collared, and released. Of those, five dams abandoned seven calves. Contingency plan sends moose calves to zoos
Last year those calves would have died, but this year the DNR made an abandonment contingency plan (ACP) and used it to save all but one calf.
“Operating off a 2014 ACP we developed with our consulting veterinarian and the Minnesota Zoo, we retrieved all but one abandoned calf in good, viable condition and delivered them to the Minnesota Zoo. The Minnesota Zoo was in need of additional moose as they were down to one animal. They plan to keep five (two males and three females) of the six calves and have identified other zoos to accept additional calves,” said DelGiudice.
Natural abandonment of newborn calves for a variety of reasons is not uncommon and has been well documented. “It is possible that unobserved factors (e.g., poor condition of the dam, proximity of predators) may have contributed to some of the abandonment behavior we observed,” said DelGiudice. Collaring provides important data
“From May 21 to June 2, we captured 10 additional calves from eight dams with no capture-related abandonments. The new, much scaled down approach is working very well and we may be able to GPScollar a few more calves before the season is complete.
“So overall, 22 calves (nine females, 13 males) have been captured from 17 dams. These included five sets of twins (29 percent of twins) and 12 single calves.
“Of the 22, two slipped their collars off, six were abandoned by their dams and brought to the Minnesota Zoo, and one died from not being nursed by its dam though she was close by,” he said.
Thirteen of 22 collared calves are being studied for survival and natural causes for mortality, but wolves have killed two, leaving researchers 11 in the study.
“The GPS collars provide the most important data, including frequent location fixes, movement, continuous proximity to their dams, habitat use, and the ability to monitor survival and rapidly investigate specific causes of mortality,” said DelGiudice.
The calf study dovetails with an adult study of more than 100 moose also fitted with GPS tracking devices. When the moose stops moving for a period of six hours it is assumed dead, and researchers try to get to the animal within 24 hours to determine what has killed it. Any longer and the fallen moose will likely have been eaten.
The moose population in northeastern Minnesota has fallen from an estimated 8,840 in 2006 to a little over 4,200 today.
Theories abound into what is causing the calamity—everything from global warming, a lack of browse, winter ticks, deer ticks, disease and predators—and maybe a combination of those things—but scientists want to figure out why moose are dying to see if there is anything they can do to help before the moose disappear from northeastern Minnesota.
DelGiudice said, “Studying calf production, survival, and causes of mortality is critical to understanding the decline of Minnesota’s moose population.”
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