J. B. Davis
H.W. Essig
P.D. Gerard
K. J. Reinecke
R.M. Kaminski
2003
<p>Acorns<span> of bottomland red oaks (Quercus spp.) are an important </span>food<span> of North American </span>wood<span> </span>ducks<span> (Aix sponsa). Barras et al. (1996) demonstrated that female </span>wood<span> </span>ducks<span> selected willow oak (Q. phellos) </span>acorns<span> over </span>other<span> species. We measured </span>true<span> </span>metabolizable<span> </span>energy<span> (TME) derived by captive, wild-strain, adult female </span>wood<span> </span>ducks<span> from </span>acorns<span> of willow oak, water oak (Q. nigra), cherrybark oak (Q. pagoda), and pin oak (Q. palustris) to determine whether female </span>wood<span> </span>ducks<span>' preference for willow oak </span>acorns<span> was related to TME. Estimates of TME within </span>acorn<span> species were relatively precise, yet we did not detect variation in TME among </span>acorn<span> species (P=0.31); hence, we estimated TME across species (2.76±0.033 [SE] kcal/g dry mass; n=34). We concluded that TME apparently did not explain female </span>wood<span> </span>ducks<span>' preference for willow oak </span>acorns<span> and hypothesized that morphological characteristics of willow oak </span>acorns<span> may be proximate cues related to selection by </span>wood<span> </span>ducks<span>. We also summarized known TME estimates for </span>acorns<span> fed to </span>wood<span> </span>ducks<span> and mallards (Anas platyrhynchos), and natural and agricultural </span>foods<span> fed to mallards, northern pintails (A. acuta), blue-winged teal (A. discors), and Canada geese (Branta canadensis). We found that </span>acorns<span> and moist-soil plant seeds and tubers provided, on average, about 76% of the TME in agricultural seeds. Thus, bottomland-hardwood and moist-soil habitats have potential to provide significant amounts of dietary </span>energy<span>, as well as greater diversity of </span>foods<span> and nutrients than croplands. Researchers should continue to determine TME of common </span>foods<span> (plant and animal) of </span>waterfowl<span>, and use TME in estimating </span>waterfowl<span> habitat carrying capacity (e.g., Reinecke et al. 1989). Additionally, large-scale, reliable estimates of plant and animal </span>food<span> availability in bottomland-hardwood and moist-soil habitats are needed to evaluate carrying capacity of landscapes important to </span>waterfowl<span>, such as the Mississippi Alluvial Valley (MAV).</span></p>
application/pdf
10.2307/3802712
en
Wildlife Society
True metabolizable energy for wood ducks from acorns compared to other waterfowl foods
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