Ranchers have long said that wolves cause weight loss in cattle, and now a study confirms such loss in calves on western Montana ranches.

A recent study was completed by University of Montana professors and graduate students, examining the effect on herd weight after a wolf makes a kill in that herd.

The results, detailed in a UM news release, showed a decrease of 22 pounds in the average weight of calves in an average herd of 264 head of calves after the confirmed wolf kill. Ranchers are reimbursed about $900 for a single wolf kill. But the stress on the rest of herd can mean a loss of over $6,600 in later sales of the rest of the animals.

The study, "Crying Wolf? A Spatial Analysis of Wolf Location and Depredations on Calf Weight," was published in the January 10th American Journal of Agricultural Economics.

The research was authored by associate Economics professor Derek Kellenberg, Wildlife Biology associate professor Mark Hebblewhite and graduate students Joseph Ramler and Carolyn Syme.

The news release also mentioned that the Montana Department of Fish, Wildlife and Parks helped - analyzing about 15 years of data, including depredations on 18 ranches.

The study noted that other factors such as snowfall, precipitation and temperature are the main factors in variation of annual calf weights. However, Kellenberg said, "This study helps quantify some of the indirect costs that have not previously been accounted for."

There are more details at the UM Economics Department website.