Wolves attack moose calf

[Lee Borgersen]

Wolf attack still the leading cause of moose calf mortality.

REGIONAL— The results of the second year of the Department of Natural Resources’ moose calf study have further confirmed that wolf attack is the predominant cause of death for young moose in northeastern Minnesota. Of the six moose calves for which a natural cause of death is known, four died in wolf attacks, one was killed by a bear, and another died of an infection.

Researchers note that the sample size is particularly small this year, due to an early problem with abandonment, and a later problem with slipped GPS collars, and that the results need to be interpreted cautiously.

In total, 25 moose calves were captured and collared this year, according to Glenn DelGiudice, who heads up the study for the DNR.

Of those 25, moose cows abandoned eight calves after capture (six were recaptured and sent to zoos), five were killed by predators, one died of infection, and ten slipped their collars, so researchers don’t know how many remain alive.

While the research was plagued with problems this year, the team did make some important discoveries, particularly on capture methods. The initial capture method, which included a small team of researchers, who maintained control of the calves for several minutes, led to seven abandonments out of the 12 calves captured. At that point, researchers regrouped and developed a new method using a team of two researchers who would capture a calf, quickly attach a collar, and leave immediately, usually in under one minute.

The new method sharply reduced the abandonment problem, according to DelGiudice. Under the new protocol, only a single cow abandoned calves, a set of twins born late in the season. One of the two was recaptured and sent to a captive facility, while the other died. DelGiudice said the abandonment may have been natural given the late birth of the pair.

Given the relatively high degree of success, DelGiudice expects to have much greater success in 2015. “With our new capture approach, we hope to be able to capture 50-60 calves next season,” said DelGiudice. Combined with the past two years, that would provide the study with a usable sample size of as many as 100 calves, he added.   

Meanwhile, DelGiudice said his team has been in touch with the German manufacturer of the radio collars asking for modifications to prevent the collars from falling off prematurely. Of the 25 collars attached to moose calves this year, ten had fallen off within 90 days. While the collars are designed to break away at some point, the premature loss of collars limited the researchers’ ability to further study those calves. By the end of the summer, all of the ten surviving moose calves had slipped their collars and could no longer be tracked by researchers.

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