Adaptations for animal dispersal of one-seed juniper seeds.

Distributional patterns of one-seed juniper seeds and seedlings show that most seeds are found directly beneath source trees but most seedlings are found away from the source trees. Thus, seeds dispersed away from source trees seem to have a better chance of germination and growth than seeds beneath source trees. Seed distribution patterns indicate haphazard animal dispersal rather than directional dispersal by water runoff or gravity. One-seed juniper appears to have adaptations favoring zoochory over other types of dispersal methods. Seeds are not well protected from animals but are presented in an attractive, abundant, easily accessible and nutritious fruit. Fruit ripening occurs just before the arrival of avian winter residents in the piñon-juniper woodlands. Several of these species are potential dispersal agents. Seeds passed through the intestines of Townsend's Solitaires showed lowered germination compared to untreated seeds but these birds are probably good dispersers.