A record-breaking heatwave reduces breeding success and impairs growth in a wild bird population
- 1University of Oxford
Abstract
Most evidence of the consequences of climate change in natural systems has focussed on shifts in mean temperature (1,2), but the effects of extreme climatic events (ECEs) remain far less understood. This is particularly true for very severe ECEs that may occur only once every few decades. Understanding the consequences of these severe events for natural populations is nonetheless critical, since their frequency is predicted to rise under current climate change (3). Here we combine a unique long-term dataset spanning almost five decades of breeding (>20,000 events) and morphological data (>120,000 observations) in adult and nestling great tits (Parus major) and blue tits (Cyanistes caeruleus) with fine-scale temperature records to examine the effects of an unprecedented heatwave in May 2026 on breeding success and morphology. Average temperature during the heatwave (22-29 May 2026) was 7.85 C above the historical record, reaching +10.5 C (+4.32 SD) at its peak (25-26 May). These record-breaking temperatures significantly reduced adult breeding success and nestling bmass relative to expectation in the absence of a heat-wave. Given the heatwave was widespread (Fig. 1A), our findings from a single, exceptionally well-studied population are likely to generalise to other species exposed to the same event, providing key evidence that severe ECEs can substantially harm wild populations.
Related
- Simulated heatwave reduces resilience to subsequent combined high‐temperature and high‐carbon‐dioxide stress in a diatom
- Same-sex sexual behaviour reduces reproductive success but mitigates aggression in a subsocial insect
- Persistent effects of experimental heatwave duration on population dynamics.
- Individual variation in glucocorticoid plasticity to temperature is not associated with reproductive success in a wild songbird population
- Genotyping by Sequencing (GBS) uncovers genetic diversity and population structure for salicornia breeding programs in Iran
BibTeX
@misc{lopezidiaquez2026recordbreaking,
title = {{A record-breaking heatwave reduces breeding success and impairs growth in a wild bird population}},
author = {D. Lopez-Idiaquez and D. Satarkar and B. C. Sheldon},
howpublished = {bioRxiv},
year = {2026},
month = aug,
doi = {10.64898/2026.08.29.747719},
url = {https://www.biorxiv.org/content/10.64898/2026.08.29.747719v1},
note = {CC BY},
}
RIS
TY - UNPB
TI - A record-breaking heatwave reduces breeding success and impairs growth in a wild bird population
AU - D. Lopez-Idiaquez
AU - D. Satarkar
AU - B. C. Sheldon
PY - 2026
DA - 2026/08/29
PB - bioRxiv
DO - 10.64898/2026.08.29.747719
UR - https://www.biorxiv.org/content/10.64898/2026.08.29.747719v1
AB - Most evidence of the consequences of climate change in natural systems has focussed on shifts in mean temperature (1,2), but the effects of extreme climatic events (ECEs) remain far less understood. This is particularly true for very severe ECEs that may occur only once every few decades. Understanding the consequences of these severe events for natural populations is nonetheless critical, since their frequency is predicted to rise under current climate change (3). Here we combine a unique long-term dataset spanning almost five decades of breeding (>20,000 events) and morphological data (>120,000 observations) in adult and nestling great tits (Parus major) and blue tits (Cyanistes caeruleus) with fine-scale temperature records to examine the effects of an unprecedented heatwave in May 2026 on breeding success and morphology. Average temperature during the heatwave (22-29 May 2026) was 7.85 C above the historical record, reaching +10.5 C (+4.32 SD) at its peak (25-26 May). These record-breaking temperatures significantly reduced adult breeding success and nestling bmass relative to expectation in the absence of a heat-wave. Given the heatwave was widespread (Fig. 1A), our findings from a single, exceptionally well-studied population are likely to generalise to other species exposed to the same event, providing key evidence that severe ECEs can substantially harm wild populations.
ER -