The first "real" winter in several years has prompted questions from many Idahoans concerned about deer survival, but a continuing study of fawn mortality indicates relatively few winter losses to date.
With the help of dozens of volunteers, Idaho Fish and Game biologists caught and radio-collared 250 mule deer fawns last fall in 10 units across southern Idaho. This large-scale monitoring effort helps biologists predict deer population trends and is an important tool in answering questions about the causes of fawn mortality.
Fawns are the deer most vulnerable to the rigors of winter survival, but malnutrition has been identified as the cause of death in only three cases so far this winter. Of the 250 fawns collared last fall, lions took four and coyotes killed 12 while other causes — collisions with vehicles, falls from cliffs and other incidents — accounted for 11 mortalities. Coyotes typically take fawns in poor condition that likely would die anyway. Mortality from all causes to date amounts to 12 percent of the number in the study, actually a lower rate of loss than biologists usually expect during the winter.
Fawns in this study had the toughest time in the Centennial Flat area of hunt unit 36B in the Salmon Region, where the loss was 42 percent. Regional Supervisor Jim Lukens attributes fawn mortality in this region to the fact that fawns in the area have lower weight going into winter than in other parts of the state. No losses had been noted in the Hells Canyon study area as of the first week of February.
Extended winter conditions could create a higher loss rate in fawns as the young deer gradually lose more of the little body fat they carry into the cold months. An early, abundant greenup would strengthen the youngest segment of deer populations.
Copyright © 2004 J & D Outdoor Communications. All rights reserved.