DIET, NUTRITION, AND REPRODUCTIVE ... - NWIFC Access

Starkey 1996). This association of timber harvest and forage has been further
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complicated because the great quantities of forage generated after timber harvest can also
be of poor nutritional quality due to high levels of secondary plant compounds such as
tannins, especially in shrubs (Robbins et al. 1987, Happe et al. 1990). Increased sun
exposure after timber harvest has been shown to elevate tannin levels in shrubs (Robbins
et al. 1987), a concern for Roosevelt elk because shrubs make up the greatest proportion
of the diet (Jenkins and Starkey 1991). Therefore forage quality, not simply abundance,
may influence cow elk health and limit elk reproductive success in managed coastal
forests.
Elk diet and nutritional quality of elk forages have been investigated for Pacific
coast old-growth (Leslie et al. 1984, Jenkins and Starkey 1993), Pacific coast managed
forests (Jenkins and Starkey 1993), and the Rocky Mountain region (Hobbs et al. 1981,
Hobbs et al. 1982). Furthermore, recent studies on the effects of diet and nutrition on
reproductive success of captive elk have established a positive relationship between high
quality forage, pregnancy rates, and calf survival (Cook et al. 1996, Cook et al 2001,
Cook et al. 2004). However, effects of diet and nutrition on reproductive success of freeranging
elk have not been investigated. Some authors have argued that spring and
summer diet and nutrition has little affect on elk reproductive success due to the
abundance of forage during these times (Nelson and Leege 1982, Unsworth et al. 1998).
However, some recent studies found significant influences of nutrition during summer
and early autumn on ungulate reproductive success (Hudson and Adamczeweski 1990,
Cook et al. 1996, Post and Klein 1999, Cook et al. 2004). Furthermore, nutritional