Wolf and bear predation on white-tailed deer fawns in northeastern Minnesota

Whitetailed deer (Odocoileus virginianus) fawn mortality was studied during the summers of 1989 and 1990 in northeastern Minnesota. Estimated pooled mortality rates for 21 radio-tagged fawns were 0.44 for the May-June, 0.13 for the July-October, and 0.51 for the May-October intervals. Predation accounted for all mortalities, with wolves (Canis lupus) responsible for 51% of them and black bears (Ursus americanus) for 49%. Fawns from mothers gt 4 years old weighed more and survived better than fawns from young mothers, which weighed less. Of various related factors (doe age, doe mass, fawn mass, fawn birth date, and fawn blood serum urea nitrogen (SUN)), only SUN was significant between surviving and perishing fawns, fawns with low SUN survived significantly less. Fawn SUN may have been only an indirect indicator of a doe physical, or behavioral factor that was more important to fawn survival.