MINNEAPOLIS (AP) - Moose researchers in Minnesota are set to try again to put tracking collars on newborn calves as they look to find out why the animals are in decline in the state.

Next month's attempt to put collars on about 50 newborn moose is the third such effort. But about one-fourth of the 75 calves collared so far have been abandoned by their mothers, a high rate that has perplexed scientists and raised ethical questions.

Governor Mark Dayton has told the state Department of Natural Resources that this would be the last collaring attempt. Researchers say they will halt the collaring if too many calves die.

Moose are no longer found in northwestern Minnesota, and its population has fallen by more than half in the last decade in the northeastern corner of the state.