We examined the relationship of variable mast production to American black bear (Ursus americanus) reproductive parameters in 2 areas of New Mexico during 1993-2000. Mast production differed across years for each of 10 species surveyed (P < 0.001). Black bear reproductive characteristics were documented during 266 den investigations of 80 females ≥4 years old. On both study areas, acorn production by the 2 dominant oak (Quercus spp.) species appeared to have the greatest influence on natality and recruitment (P < 0.001). Neither natality nor recruitment varied following oak production indexed as 'poor' to 'good'. However, natality among eligible parous females decreased by more than 60% following years categorized as oak 'failure', and recruitment decreased by more than 70% 2 years after oak failure (P = 0.05). This suggested that only a minimum threshold of high quality food was needed for successful reproduction. Cub survival was positively associated with juniper (Juniperus spp.) production during the previous fall and combined production of juniper during the previous fall and oak production during the birth year (P ≤ 0.009). During 1999-2000, New Mexico Department of Game and Fish officers subjectively assessed mast production in our study areas. These assessments were highly correlated with our survey results (rs ≥ 0.73, P < 0.001, n = 12), indicating subjective criteria were adequate to distinguish variation in mast production. Documenting annual mast production in New Mexico, especially occurrence and frequency of mast failures, may be an effective index to subsequent black bear reproductive output during the following 2 years.
- Volume 14
- Issue 1
- Pages 1-16
- Publication Date 1 January 2003
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