Ground warming boosts cooperative transport in a temperate ant species.

Understanding how global warming affects collective behaviours is crucial, as these behaviours are widespread among social animals with key ecological roles. One direct yet underexplored consequence of global warming is rising ground temperatures, which can affect animals' collective behaviour by altering coordination, physiology and communication. As eusocial ectotherms, ants provide an ideal model for studying the impacts of ground warming on collective behaviours such as cooperative transport-the coordinated movement of large objects by multiple individuals. To test cooperative transport performance under warming conditions, we experimentally increased ground temperature and offered artificial baits to Dorymyrmex tener, a temperate ant species native to the Patagonian steppe (Argentina). Warming enhanced all cooperative transport metrics: bait removal success, transport accuracy and velocity. Notably, cooperative transport metrics remained at peak levels even under extreme ground temperatures (40-50°C), deviating from typical unimodal thermal performance curves and suggesting that cooperative behaviours may be highly tolerant to warming. These improvements were primarily driven by increased velocities, indicating a physiological mechanism for the effects of warming on cooperative transport behaviour. Our findings provide new insights into how social animals may respond to climate change and highlight the need to consider collective behaviours within ecological predictions under future warming scenarios.