One of the plants that we study is Jeffrey pine, which shed its relatively large, winged seeds on the ground during mid September.

Rodents, like this yellow pine chipmunk, gather the seeds and eat many, but also make many caches in the soil

A chipmunk cache that has been emptied by a rodent (not seed husks).

Jeffrey pine seedlings that have recently germinated from an animal cache.

Surveying the landscape for radioactive seed caches. We label seeds with scadium-46 or iron-59 (gamma emitters) so that we can determine where chipmunks and other rodents have hidden them.

Stephen Vander Wall

Stephen Vander Wall
Plant-animal interactions involving seeds

My research examines how animals influence the dispersal and establishment of plants. Animals can serve as both predators of seeds and as dispersers of propagules. My students and I focus primarily on how scatter-hoarding rodents and jays disperse the seeds of plants and how these activities affect the evolution of fruit and seed traits. We have worked on several tree and shrub species in Little Valley as well as plants restricted to the arid mountain ranges and deserts to the east.


A map showing the complex history of 10 seeds from one artificial cache site (lower right corner of large square) after rodents had pilfered the cache and reburied the seeds elsewhere. Circles and squares represent cache sites, arrows represent seed movement, and an * indicated seeds that have germinated the following spring. This diagram indicates how dynamic cached seeds can be (from Vander Wall 2002).

Cache Map