Do cubs have high annual mortality?
Cub survival is influenced by food abundance and quality, physical condition of the mother, social factors, litter size, experience of the mother, cub birth weight, and estimation technique. Mothers who are nutritionally stressed, or first-time breeders, are more likely to lose cubs than are well-fed mothers. In Massachusetts, litter order was the principal factor in determining minimum first-year survival. Ten of 12 known first litters had 0% cub survival to 1 year, while 49% of second and later litters had 100% survival through the first year. Since most first litters were born to 3-year-old sows, it is likely that the mother failed to attain the minimum weight necessary to successfully raise cubs. Annual cub survival throughout North America has varied from 27% on Long Island, Washington, to 90% at Dry Creek, Arkansas. In one Massachusetts study, 65% of female cubs (but only 10% of males) survived until adulthood. A later study in the same area estimated 63% annual survival (sexes c
