Acorn dispersal by the blue jay (Cyanocitta cristata)

Summary

Blue jays transported and cached 133,000 acorns from a stand of Quercus palustris trees in Blacksburg, Virginia, representing 54% of the total mast crop. A further 20% (49,000) of the mast crop was eaten by jays at the collecting site. A large proportion of the nuts remaining beneath the collecting trees was parasitized by curculionid larvae. The number of nuts transported per caching trip ranged from 1–5 with a mean of 2.2. Mean distance between seed trees and caches was 1.1 km (range: 100 m–1.9 km). Jays appeared to choose species with small- to medium-sized nuts (Quercus palustris, Q. phellos, Q. velutina, Fagus grandifolia) and avoided the larger nuts of Q. borealis and Q. alba.

Nuts were cached singly within a few meters of each other and were always covered with debris. Covering may improve germination and early growth by protecting the nut and radicle from desiccation. The vegetation structure of most suburban caching sites was analogous to open, disturbed environments in more natural landscapes. The presence of numerous Quercus seedlings in jay caching sites and the tendency for jays to cache nuts in environments conducive to germination and early growth indicate that blue jays facilitate colonization of members of the Fagaceae.