• Bite characteristics of wapiti (Cervus elaphus) in seasonal Bromus-Poa swards

      Jiang, Z. G.; Hudson, R. J. (Society for Range Management, 1994-03-01)
      We used a cubic sampling quadrat to study the 3-dimensional structure of volunteer Bromus-Poa swards, and explored the relationship of bite depth and sward height as a determinant of bite sizes of wapiti (Cervus elaphus) in the mixed-wood parklands of central Alberta, Canada. The vertical biomass distribution of the sward was pyramidal with leaves dominating the top stratum. Bite depths of yearling and adult wapiti were not significantly different but both were influenced by sward height and season. Wapiti selected bites in both vertical and horizontal dimensions. In spring, wapiti selected vertically, taking green leaves in the top layer of the sward. They selected forbs horizontally in summer and selected leaves vertically in mature autumn swards. Based on the relationships among bite depth and sward height, biomass and sward height, as well as vertical biomass distribution, we calculated expected bite sizes of wapiti on seasonal pasture. We also predicted changes of dietary protein and neutral detergent fiber with increasing bite depth. On spring swards, calculated dietary protein decreased and fiber increased as animals grazed deeper into the swards. In summer and autumn, dietary protein peaked as wapiti cropped about half of the height of the sward whereas dietary fiber was relatively constant. Wapiti adjusted their bite depth to select forage containing at least 14% protein in spring, summer, and autumn. The sacrifice of bite size in tall summer and autumn swards was compensated by diet quality.
    • Pre-laying nutrition of sage grouse hens in Oregon

      Barnett, J. K.; Crawford, J. A. (Society for Range Management, 1994-03-01)
      Diet, dietary selection, and nutritional composition of the food of sage grouse (Centrocercus urophasianus) hens were determined during the pre-laying period in southeastern Oregon in 1990 an 1991. We collected 42 female sage grouse during a 5-week period preceding incubation (4 March-8 April). Sagebrush (Artemisia spp.) was the most common among 21 foods consumed but forbs composed 18 to 50% of the diet by weight. Desert-parsley (Lomatium spp.), hawksbeard (Crepis spp.), long-leaf phlox (Phlox longifolia Nutt.), everlasting (Antennaria spp.), mountain-dandelion (Agoseris spp.), clover (Trifolium spp.), Pursh's milk-vetch (Astragalus purshii Dougl.), buckwheat (Eriogonum spp.), and obscure milk-vetch (A. obscurus) were the primary (greater than or equal to 1% of the diet by weight) forbs consumed. Forbs were used selectively over sagebrush in both low and big sagebrush cover types. All forbs were higher in crude protein and phosphorus and many were higher in calcium than sagebrush. Consumption of forbs increased nutrient content of the composite diet. Substantially fewer forbs were present in the diet in 1991 than in 1990, which coincided with reduced sage grouse productivity on the study area. These results suggest that consumption of forbs during the pre-laying period may effect reproductive success by improving nutritional status of hens.