Preference of Selected Grains by Geese

Abstract

The preference of 12 livetrapped adult geese for several grains was tested over a 49-day period. During this time the average daily consumption per goose was approximately 182 grams. Rice (Oryza sativa) was preferred 2 : I over barnyard grass or watergrass (Echinochloa crusgalli) but watergrass was preferred 5-6 : 1 over milo (Sorgum vulgare), alkali bulrush (Scirpus robustus) and safflower (Carthamus tinctorius), 9: 1 over barley (Hordeum vulgare) and 12: 1 over lana vetch (Vicia dasycarpa). Examination of the stomach contents of wild geese in the Sacramento Valley by personnel of the California Department of Fish and Game also indicated that the volume of rice consumed was from 1.5-7 times greater than that of watergrass. Marked increases in grain consumption were assoicated with sudden declines in minimum air temperature, increased air movement, or a sudden lessening of daily air temperature fluctuations. Blood chemistry tests verified that these geese maintained a healthy nutritional state. Each year agriculture, industry, and urban growth reduce the waterfowl habitat. This loss of available land has stimulated the conversion of remaining marshlands and marginal lands into good waterfowl habitats, but because of the limited areas available it is necessary to know which types of forage will be most beneficial to waterfowl. The types of plants preferred by waterfowl can be determined by studying their food habits. The usual method of determining the food habits and grain preferences of waterfowl is to examine stomach contents. Although this method indicates what has been eaten, it does not distinguish the actual preference of a food from its availability. The purpose of this study was to supply information about preferences of geese for various grains, independent of availability. Background information was provided by an earlier study of preferences of a mixed group of waterfowl for seven grains (McFarland et al. 1963). Based on that study barnyard grass or watergrass was selected as the standard reference grain for testing the preference of geese for other grains. MATERIALS AND METHODS A group of 12 livetrapped adult geese consisting of three western Canada geese (Branta canadensis moffitti), two cackling geese (Branta canadensis minima), five lesser snow geese (Chen hyperborea), and two white-fronted geese (Anser albifrons) were maintained in a partly enclosed screened outdoor pen from November 26, 1962 to January 14, 1963. Two grain-preference tests were conducted during this period in which the geese were given various grains ad libitum in identical stainless steel pans distributed randomly each day. The amount of grain eaten was determined by weight loss from each pan. No correction was made for spillage, which was minimal. In Test 1 the preference for watergrass was compared to that for whole barley. In Test 2 the preference for watergrass was compared to that for paddy rice, milo, alkali bulrush, safflower, and lana vetch. An average preference value for each grain was calculated by comparing the average amount of grain eaten to the average amount of watergrass eaten during the test period (McFarland et al. 1963:208). At the conclusion of Test 2 a 5-ml heparinized blood sample was obtained by wing 1This study was supported in part by U. S. Public Health Service research grant GM-08538 and by Federal Aid in Wildlife Restoration Project, California W-30-R.