1 We investigated the spat io-temporal variation in the interactions betwee
n the juniper Juniperus communis and its vertebrate frugivores (avian dispe
rsers of Turdus spp. and predatory rodents Apodemus sylvaticus) in the Medi
terranean mountains of south-east Spain.
2 Frugivore activity was evaluated at six sites and for 3 years, in relatio
n to both plant reproductive traits (plant size, cone crop and cone size) a
nd characteristics of the immediate environment (distance to the nearest fe
male, abundance of perches, fruiting environment and habitat).
3 Plant characteristics and levels of frugivory varied strongly among the s
ix populations. Cone production, cone size and frugivory also differed sign
ificantly among years for the same population. Avian frugivory was only occ
asionally affected by density of cones per plant, abundance of perches or a
bundance of other fruiting species, or by habitat. Rodent predation was pos
itively related only to the density of cones per plant and then only in two
4 Levels of both avian frugivory and rodent predation significantly increas
ed in populations with higher cone production.
5 Both groups of vertebrate frugivores responded to the spatio-temporal var
iation in cone abundance at a regional scale, discriminating more between j
uniper populations than between individual plants within a population. The
outcome of interactions with frugivores at the individual plant level thus
proved more dependent on the whole-population characteristics than on indiv