Enemies with benefits: Integrating positive and negative interactions among terrestrial carnivores

Interactions among terrestrial carnivores involve a complex interplay of
competition, predation, and facilitation via carrion provisioning, and
these negative and positive pathways may be closely linked. Here, we
developed an integrative framework and synthesized data from 256 studies
of intraguild predation, scavenging, kleptoparisitism, and resource
availability to examine global patterns of suppression and facilitation.
Large carnivores were responsible for one third of mesocarnivore mortality
(n = 1,581 individuals), and intraguild mortality rates were
superadditive, increasing from 10.6% to 25.5% in systems with two versus
three large carnivores. Scavenged ungulates comprised 30% of mesocarnivore
diets, with larger mesocarnivores relying most heavily on carrion. Large
carnivores provided 1,351 kg of carrion per individual per year to
scavengers, and this subsidy decreased at higher latitudes. However,
reliance on carrion by mesocarnivores remained high, and abundance
correlations among sympatric carnivores were more negative in these
stressful, high-latitude systems. Carrion provisioning by large carnivores
may therefore enhance suppression rather than benefiting mesocarnivores.
These findings highlight the synergistic effects of scavenging and
predation risk in structuring carnivore communities, suggesting the
ecosystem service of mesocarnivore suppression provided by large
carnivores is strong and not easily replaced by humans.