Methodological challenges in avian nestbox temperature manipulation experiments: a review with recommendations

Devi Satarkar , David López-Idiáquez, Irem Sepil, Ben C. Sheldon

Experimental manipulation of nest temperature - particularly in nest boxes, given ease of access and control - has become increasingly used for understanding the ecological impacts of climate change on wild birds. While field experiments are crucial for establishing causal links between temperature variation and biological responses, they present numerous logistical challenges. Moreover, reproducibility between such studies remains a challenge, largely due to heterogeneity among methodologies. Here, we comprehensively review published nestbox temperature manipulation studies, and document widespread variation in heating protocols and temperature measurement approaches. We also present a case study of a pilot temperature manipulation experiment in blue tits (Cyanistes caeruleus), documenting the project from planning through field implementation. By outlining methodological constraints and logistical pitfalls, we demonstrate the value of transparently reporting setbacks to guide future research. Furthermore, we highlight how temperature logger placement and calibration can introduce substantial variation in recorded nest temperatures. Specifically, we show that small changes in logger position can shift apparent treatment effects by an order of magnitude, revealing a critical source of methodological inconsistency that is rarely discussed in the literature. Building on key lessons from our field experiment, we outline a practical framework for nestbox temperature manipulation experiments, emphasising pilot testing, adaptive field protocols, welfare safeguards, and standardised temperature measurement. By transparently reporting the logistical barriers encountered in our pilot study, we provide a practical roadmap to improve rigour, comparability, and welfare outcomes in avian climate change research.