Data from: Environmental variables influence patterns of mammal co-occurrence following introduced predator control

Co-occurring species often overlap in resource use and can interact in
complex ways. However, shifts in environmental conditions or resource
availability can lead to changes in patterns of species co-occurrence,
which may be exacerbated by global escalation of human disturbances to
ecosystems, including conservation directed alterations. We investigated
the relative abundance and co-occurrence of two naturally sympatric mammal
species following two forms of environmental disturbance: wildfire and
introduced predator control. Using 14 years of abundance data from repeat
surveys at long-term monitoring sites in south-eastern Australia, we
examined the association between a marsupial, the common brushtail possum
Trichosurus vulpecula, and a co-occurring native rodent, the bush rat
Rattus fuscipes. We asked: Is the increase in abundance of common
brushtail possums following control of an introduced predator associated
with a decline in abundance of the bush rats? Using Bayesian regression
models, we tested hypotheses that the abundance of each species would vary
with changes in environmental and disturbance variables, and that the
negative association between bush rats and common brushtail possums was
stronger than the association between bush rats and disturbance. Our
analyses revealed that bush rat abundance varied greatly in relation to
environmental and disturbance variables, whereas common brushtail possums
showed relatively limited variation in response to the same variables.
There was a negative association between common brushtail possums and bush
rats, but this association was weaker than the initial decline and
subsequent recovery of bush rats in response to wildfires. Using
co-occurrence analysis, we can readily infer negative relationships in
abundance between co-occurring species, but to understand the impacts of
such associations, and plan appropriate conservation measures, we require
more information on interactions between the species and environmental
variables. Co-occurrence can be a powerful and novel method to diagnose
threats to communities and understand changes in ecosystem dynamics.