HAMILTON, Mont. (AP) — Wildlife biologists engaged in the second year of a three-year elk study in the Bitterroot Valley plan to use a different style of electronic ear tag after more than half of them attached to newborn calves fell off prematurely.

Kelly Proffit of Montana Fish, Wildlife and Parks tells the Ravalli Republic that calves captured this spring will be fitted with an older design that has been used successfully in other research projects.

The study so far has 42 documented mortalities of calves previously captured in the spring and winter.

The study found 16 killed by cougars, four by wolves, four by bears, five were natural mortalities and one was related to the capture.

The cause of death for 12 couldn't be determined.