SeedsFive seed types used in foraging experiment. Millet and sunflower (top) are non-native seeds.  Squash seeds (top center) are native seeds for which we did not expect strong natural selection to minimize odors.  Antelope bitterbrush and Jeffrey pine seeds (bottom) are native seeds scatter-hoarded by rodents and for which there should be strong natural selection to minimize odors.

Long-eared chipmunks and other rodents forage for the cached seeds.

Jennifer Hollander

Jennifer HollanderMy research in the Whittell Forest in Little Valley has focused on the role of olfaction in rodents locating cached seeds, and whether some seeds have evolved traits to avoid detection by foragers once they have been cached.  We conducted a study to examine the ability of rodents to detect caches made with native and non-native seeds under wet and dry conditions.  We established transects with artificial cache stations containing either one of two species of native seeds or one of three species of non-native seeds.  Under dry conditions, rodents found non-native seed caches much more rapidly than native seed caches.  Wet conditions resulted in a similar order of detectability, however, all species of seeds were located much faster than under dry conditions.  Natural selection has likely acted on the native seeds to reduce their detectability by olfaction, and potentially reduce predation upon those seeds.

My future areas of research in Little Valley will continue to focus on seed dispersal by seed caching rodents.  One area of interest I have is the potential for deer mice to transmit hantavirus through cached seeds.  Deer mice place seeds in their cheek pouches for transport to cache sites, and seeds come in contact with saliva.  Saliva is known to contain hantavirus particles in infected rodents.  Other rodents that are not infected may pilfer the seeds cached by an infected rodent and come in contact with the virus.

Results from the study below (Download PDF).  Native seeds were removed more slowly, especially under dry conditions.

Study Results

Hollander, J. L., S. B. Vander Wall, and W. S. Longland. 2012. A comparison of the detectability of wildland and cultivated seeds by foraging rodents.  Western North American Naturalist 73:339-347