Implications of desert rodent seed preferences for range remediation

Abstract

Many desert plants germinate and establish from seed caches made by granivorous rodents. As a preliminary test of the feasibility of using rodent seed-caching activities to enhance seedling emergence of native desert plants, we tested desert heteromyid rodents for preferential consumption and/or caching of native ("target") seeds versus a commercial ("decoy") seed. The target/decoy seed concept relies on rodents caching both seeds, and preferentially consuming an inexpensive decoy seed as a sacrifice to reduce consumption of less preferred target seeds. We used cafeteria-style, paired seed choice trials to test 2 potential target seeds known to germinate from rodent scatterhoard caches (Indian ricegrass, Achnatherum hymenoides [R. & S.] Barkworth, and four-wing saltbush, Atriplex canescens [Pursh] Nutt.) against a potential decoy seed (millet, Panicum miliaceum L.). Millet was highly preferred to saltbush, and may indeed be a useful decoy seed when saltbush is the target of range restoration. Also consistent with the target/decoy seed concept, more Indian ricegrass than millet seeds were cached in laboratory trials, and all seeds were cached in scatterhoards more than in larderhoards, where the probability of seedling emergence is negligible. However, millet seed may not always be a good candidate for a decoy seed, as it was not preferred to Indian ricegrass and was cached more frequently than saltbush. Overall, we find results of these choice tests to be encouraging for applying the target/decoy seed idea. We consider the relative merits of this idea versus traditional revegetation techniques.