Fig 1.
Mean (± 95% confidence interval) seasonal a) moisture content and b) nitrogen (N) content of female desert bighorn sheep diet during pretreatment and treatment periods on Sierra Pinta (treatment; open symbols) and Cabeza Prieta (control; closed symbols), Cabeza Prieta National Wildlife Refuge, Arizona, USA, from 2002 to 2005. Seasons are early summer (circles), late summer (triangles), autumn (squares), and winter (diamonds).
Fig 2.
Mean (± 95% confidence interval) seasonal proportion in female desert bighorn sheep diet of a) shrubs, b) forbs, c) grasses, d) trees, and e) succulents during pretreatment and treatment periods on Sierra Pinta (treatment; open symbols) and Cabeza Prieta (control; closed symbols), Cabeza Prieta National Wildlife Refuge, Arizona, USA, from 2002 to 2005. Seasons are early summer (circles), late summer (triangles), autumn (squares), and winter (diamonds). Jacobs D index values (‘X’ symbols) indicate preference (> 0) and avoidance (< 0) of forage types.
Table 1.
Estimated seasonal daily water and nitrogen (N) balance of desert bighorn sheep non-reproductive females, reproductive females (early and late breeders), and males on Sierra Pinta (treatment range) during the treatment period in Cabeza Prieta National Wildlife Refuge, Arizona, USA, from 2002 to 2005.
Intakes are calculated from dry matter intakes reported in Mazaika et al. [76], and forage moisture and N content measured in this study.
Fig 3.
Seasonal water (ml; solid line) and nitrogen (N; g; dashed line) intake of desert bighorn sheep (DBS) under average precipitation for a) non-reproductive and early breeding females, b) late breeding females, and c) males, and under drought conditions for d) non-reproductive and reproductive females, e) males, f) early breeding females, g) non-reproductive and late breeding females, h) males, i) early breeding females, and j) late breeding females in response to shifts in diet in Cabeza Prieta National Wildlife Refuge, Arizona, USA. Panels f to j are calculated from forage moisture and N content in pretreatment under drought conditions, and DBS diet in treatment under above-average precipitation. The start of lines at the left represent observed diet proportions (i.e., without shifts). Horizontal lines represent DBS daily maintenance requirements for water (solid) and N (dashed), and thus intakes above these lines represent a positive balance.