The 2008 Joint Meeting of the Society for Range Management and the America Forage and Grassland Council.

Monday, January 28, 2008 - 1:40 PM

Effects of Plant Community Structure and Composition on Insect Abundance and Diversity: Implications for Sage-Grouse Brood Rearing

Erica A. Ersch1, Tamzen K. Stringham1, Jeffrey C. Miller1, Richard F. Miller2, and Michael Gregg3. (1) Department of Rangeland Ecology and Management, Oregon State University, 202 Strand Agricultural Hall, Corvallis, OR 97331, (2) Eastern Oregon Agricultural Research Center, Burns Experiement Station, 202 Strand Agricultural Hall, Corvallis, OR 97331, (3) Hanford Reach National Monument and Saddle Mountain National Wildlife Refuge, U.S. Fish and Wildlife Service, Richland, WA 99354

Greater sage-grouse (Centrocercus urophasianus) is a species of concern in central Oregon and many areas throughout the western United States and southwestern Canada. Habitat structure and diet are critical to chick survival.  Sage-grouse chicks need insects during the first few weeks after hatching to ensure proper nutrition and increase survival rates. To date, most studies have shown ants and beetles to be the most important insects in chick diets.  However, a recent study by Mike Gregg has provided compelling data that positively correlates caterpillar presence and abundance to sage-grouse chick survival.  There is little data on the Lepidoptera species present in central Oregon and their relationship to sagebrush and rabbitbrush dominated plant communities.  To further investigate the availability of Lepidoptera for chick consumption, I am conducting a two-year project at six study sites in central Oregon. The first year of study was initiated by sampling vegetation and insects in 2007.  One site is placed within a mesic and xeric rabbitbrush (Ericameria spp. and Chrysothamnus spp.) dominated community.  The other four sites are located within two ecological sites under two different seasons of grazing.  Plant community structure and composition were measured during June and July.  Pitfall traps were used to measure the abundance of ground crawling insects, especially those of importance for sage-grouse chicks during early brood rearing.  Insects of interest include caterpillars, grasshoppers, ants, and two families of beetles.  Pitfall traps were collected between April and July to determine insect availability.  Ultra-violet blacklight traps were used once per month between May and September to capture adult Lepidoptera (moths).  Capturing moths allows a better understanding of the Lepidoptera species present in the sagebrush (Artemisia spp.) steppe community, and therefore indicate species of caterpillars that may be available for chicks to eat.

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