WOLF AND BEAR PREDATION ON WHITE-TAILED DEER FAWNS IN NORTHEASTERN MINNESOTA

White-tailed deer (Odocoileus virginianus) fawn mortality was studied during the summers of 1989 and 1990 in northeastern Minnesota. Estimat ed 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 inte rvals. Predation accounted for all mortalities, with wolves (Canis lup us) responsible for 51% of them and black bears (Ui sus americanus) fo r 49%. Fawns from mothers >4 years old weighed more and survived bette r than fawns from young mothers, which weighed less. Of various relate d factors (doe age, doe mass, fawn mass, fawn birth date, and fawn blo od serum urea nitrogen (SUN)), only SUN was significant between surviv ing and perishing fawns; fawns with low SUN survived significantly les s. Fawn SUN may have been only an indirect indicator of a doe physical or behavioral factor that was more important to fawn survival.