Assessing the Influence of Interference Competition on Ecologically Similar Species Threatened by Habitat Loss

ABSTRACT Understanding the strength and direction of negative species interactions is essential for managing co‐occurring at‐risk species. The sympatric kangaroo rats Dipodomys stephensi and Dipodomys simulans are both threatened by habitat loss, but conservation efforts have focused on D. stephensi . A fine‐scale habitat partitioning study provided evidence for intense interference competition between the species. To determine whether one species dominates the other, we staged dyadic encounters between residents and intruders in the field. We found a consistent asymmetry: D. simulans avoided D. stephensi , and D. stephensi residents and intruders had a 92% and 76% chance of defeating D. simulans , respectively. These findings suggest that conservation translocations of D. stephensi are unlikely to be negatively affected by D. simulans but could exacerbate ongoing declines in D. simulans , highlighting the need to incorporate behavioral interference into conservation planning and management.