Rodent consumption of fourwing saltbush seeds and seedlings. Clements, Charlie ^*,1, Young, James¹, Harmon, Dan¹, ¹ USDA-ARS 920 Valley Road, Reno, NV

ABSTRACT- Fourwing saltbush (Atriplex canescens) is one of the most valuable shrubs in arid and semi-arid rangelands. Due to its' value it is a widely used native shrub in efforts to rehabilitate western rangelands. Granivorous rodents play an important role in seed harvest and dispersal of many browse species, such as antelope bitterbrush (Purshia tridentata), yet little is known on just how granivorous rodents interact with fourwing saltbush. We monitored the interaction of granivorous rodents on fourwing saltbush seeds and seedlings in northwestern Nevada during the fall and spring of 2003 and 2004, respectively. Using portable livetrap cages, we recorded 95 observations in which the 2 main rodent species at the site, desert kangaroo rat (Dipodomys deserti) and the Merriam's kangaroo rat (Dipodomys meriiami) consumed 39% of the fourwing seeds available to them. The desert and Merriam's kangaroo rats consumed 29% and 45%, respectively. They did not clean and harvest the seed as we had hypothesized, but rather removed 1 or 2 wings and removed the embryo. We also recorded 61 observations in which these rodents consumed 96% of the fourwing saltbush seedlings available to them. Fourwing saltbush seedling predation is much higher than we have previously experienced with antelope bitterbrush. The absence of seed harvest, cleaning, and assumed subsequent caching that would follow is somewhat mysterious to us as these rodents would benefit from the sprouting caches the following spring.

KEY WORDS: seed predation, seedling predation, Atriplex canescens, salt desert