Energy Content and Retention by Ragweed and Sunflower Seeds during Fall and Winter

Abstract

Since winter and early spring are nutritionally the most critical periods of the year for wild avian species in temperate regions, the availability of basic energy sources during these periods is vitally important. Many have studied food habits of game birds like bobwhite quail (Colinus virginianus) but relatively few researchers have been concerned with energy content of the more common food items. Even more neglected are studies designed to determine basic energy retention by seeds when exposed to weathering. Baumgartner et al. (1952 p. 345) and Korschgen (1948) found bobwhite quail fed heavily on seeds of ragweed (Ambrosia sp.) and sunflower (Helianthus sp.) when available. Robel (1963 p. 781) reported sunflower and ragweed seeds to be a major constituent in the diet of Kansas bobwhite quail during fall and early winter. However, use of these two seed sources decreased as winter progressed, presumably due to decreased availability (Robel and Slade, 1965 p. 205). Because these two seed sources are commonly preferred by bobwhite quail, one might expect theit energy content to be high, otherwise natural selection would favor that portion of the population that preferred a seed source higher in energy value. If energy content of these seeds decreased as winter progressed, it would be of survival value for the population to exhibit a change in seed preference during late winter and early spring. Decreases of ragweed and sunflower seeds in the diet of quail could logically be due to a change in food preference by quail as well as a decrease in availability. This study was initiated to determine basic energy content of annual sunflower (Helianthus annuus)2 and giant ragweed (Ambrosia trifida) and their energy retention during the fall and winter.