Confirm the behavioural-retreat mechanism underlying the thermal plateau

Establish whether behavioural retreat into nests under progressive warming causes the observed plateau in ant thermal mortality hazard, using direct behavioural assays that measure retreat responses and realised thermal exposure.

Background

The study detects a sharp reduction in the temperature–mortality slope above an estimated breakpoint of 20°C daily maximum air temperature. The authors interpret this plateau as consistent with behavioural buffering, such as foragers retreating to nests when surface temperatures exceed their activity optimum.

The proposed mechanism remains unresolved because retreat behaviour was not observed directly. Direct behavioural assays under progressive warming are therefore needed to determine whether the plateau reflects behavioural thermoregulation rather than a physiological ceiling or guild-level heterogeneity.

References

The pattern is consistent with behavioural buffering --- foragers retreating to the nest once surface temperatures exceed the activity optimum, which would cap realised thermal exposure \citep{Andrew2013, Youngsteadt2023} --- but this remains a hypothesis inferred from the mortality pattern rather than a direct behavioural measurement (we develop the interpretation in \S\ref{sec:claim3}). External evidence for nest retreat under heat is well documented in genera present in this assemblage.

— Body size predicts how long ant workers live - but not how they age or how they die from heat  (2608.14245 - Moscardi et al., 14 Aug 2026) in Results, Section 3.3, “Claim 3 — Thermal risk is nonlinear and taxonomically patterned; body size offers no protection”