• Effect of Jointworms on the Growth and Reproduction of Four Native Range Grasses of Idaho

      Spears, B. M.; Barr, W. F. (Society for Range Management, 1985-01-01)
      A study of jointworm larvae (Tetramesa Walk.) feeding in 4 native range grasses of Idaho was conducted to determine effects on their hosts. These insects were responsible for a decrease in the length of reproductive culms of red threeawn (Aristida longiseta Steud.), bottlebrush squirreltail (Sitanion hystrix (Nutt.) J.G. Smith), sand dropseed (Sporobolus cryptandrus (Torr.) A. Gray), and needleandthread (Stipa comata Trin. and Rupr.) Jointworms caused a decrease in the number of spikelets produced per inflorescence in bottlebush squirreltail and needleandthread, and a decrease in the inflorescence length of sand dropseed. They caused a decrease in seed weight, percentage germination, and germination rate of all 4 grasses. By adversely affecting native grasses, these insects contribute significantly to the degradation of valuable rangelands, and their control may be desirable.
    • Effect of Forage Depletion on the Feeding Rate of Wapiti

      Hudson, R. J.; Nietfeld, M. T. (Society for Range Management, 1985-01-01)
      We evaluated forage intake rates of wapiti (Cervus elaphus nelsoni) during the depletion of a grass sward over a 7-day period. Bite sizes increased linearly with forage biomass and plant height within the range of our data. Maximum foraging rates of 45 cropping bites per minute declined exponentially at bite sizes greater than 0.2 g. Consumption rates increased asymptotically with forage biomass to a predicted asymptote of 17.6 g/min although the highest value observed was 12.6 g/min at a biomass of 2367 kg/ha. Average daily forage removals through grazing and trampling (not distinguished) were 9.5 kg per animal and did not decline as biomass was reduced from approximately 2,400 kg/ha to 800 kg/ha.
    • Changes in Diets of Wapiti during a Hunting Season

      Morgantini, L. E.; Hudson, R. J. (Society for Range Management, 1985-01-01)
      This study was conducted to assess the impact of hunting on diets of a wapiti (Cervus elaphus) population in west-central Alberta, Canada. During special winter hunts, consumption of rough fescue (Festuca scabrella) decreased from 86.9% to 34.3%, while browsing increased. The contribution of wild rye (Elymus innovatus) and wheatgrass (Agropyron subsecundum), mostly growing in forested areas, increased 15-18%. After the hunting seasons, animals returned to the same diet they had selected previously. Browse had significantly higher crude protein contents, but lower dry matter digestibility than grasses. In spite of submaintenance crude protein contents of grasses, undisturbed wapiti appeared to prefer grazing to browsing.
    • A Modified Procedure for Esophageal Fistulation of Sheep

      Stevens, E. J.; Thomson, G. G.; O'Connor, K. F. (Society for Range Management, 1985-01-01)
      Esophageal fistulation provides a well-documented standard for herbivore dietary composition studies against which other methods may be calibrated. Modified surgical procedures and animal husbandry practices are described which enabled esophageal fistulas to be fitted and maintained in free ranging sheep grazing improved mountain land pastures in New Zealand.