Data for: Cold adaptation does not handicap warm tolerance in the most abundant Arctic seabird

Arctic birds and mammals are physiologically adapted to survive in cold environments but live in the fastest-warming region on the planet. They should therefore be most threatened by climate change. Combining modelling and physiological measurements in dovekies (Alle alle) from East Greenland, we demonstrate that cold adaptation in this small Arctic seabird does not handicap acute tolerance to air temperatures more than 10 °C above their current maximum. We predict that climate warming will reduce the energetic costs of thermoregulation for dovekies, but their capacity to cope with rising temperatures will be constrained by water intake and salt balance. Dovekies evolved 15 million years ago, and their thermoregulatory physiology might reflect adaptation to paleoclimates that were substantially warmer than the present-day., Phylogenetic modelling
 
We fitted phylogenetic mixed models to existing data (Khaliq et al. 2017 Proc B 281: 20141097) for upper critical temperature (TUC) in 255 bird species. We also included information on potential sources of variation in TUC estimates due to differences in methodology among studies (McKechnie et al. 2017 J Biogeogr 44:10). Specifically, different studies estimated TUC from respirometric data obtained across different temperature ranges, which potentially influences the precision of estimates of TUC. To account for this potential source of error in TUC, we used the ‘data quality’ categories proposed by McKechnie et al. (2017) in their examination of the primary data from the Khaliq et al. (2014) dataset. Their categories were ‘Good’ (i.e., an increase in metabolic rate above thermoneutrality with a clear inflection point defining TUC), ‘Insufficient data’ (i.e., some evidence of an increase in metabolic rate above thermoneutrality, but based on measurements at too ..., , # Data for: Cold adaptation does not handicap warm tolerance in the most abundant Arctic seabird

## **Overview**

The data provided are described in three sections. We provide a brief overview of the type of data described in each section, followed by a more detailed description of the data below.

1. Field-based physiological measurements: respirometry data and associated metadata.
2. Comparative species data set: previously published data for upper critical temperature (*TUC*) measured in 255 bird species (Khaliq et al. 2014 *Proc. B* 281: 20141097) combined with published data quality categories pertaining to that data set (McKechnie et al. (2017). *J. Biogeogr.* **44**, 2424-2426).
3. Future climate scenarios: predicted land surface air temperatures under historical and future climate scenarios at the East Greenland study site, extracted from the HadGEM2-ES climate model.

## Field-based physiological measurements

#### Column headings in .csv file

*date*: date of measurement

*ch...