Relationships between ambient temperature and diurnal variation in physiological responses to acute stress in the house sparrow, Passer domesticus

These data include plasma glucose, corticosterone, heat shock proteins Hsc70 and Hsp90, and additional measures taken from wild house sparrows (Passer domesticus) at three sites in Australia. The goal of this data collection was to test how these plasma measures varied across latitude, time, and temperature.

Climate change will alter the frequency and intensity of environmental extremes, as well as diurnal rates of environmental change. The daily reaction norms of wild animals show spatial and temporal plasticity to allow appropriate physiological responses to predictable environmental challenges, but these responses have rarely been quantified in wild birds. To address this, we determined whether physiological stress indices (corticosterone [CORT], glucose [GLU], and circulating heat shock proteins) vary across a latitudinal gradient, with ambient temperature (Ta) or time of day. We sampled wild house sparrows, Passer domesticus, across three locations with varying daily rates of Ta increases in 2015 and in 2019-2020 to determine whether physiological responses to capture and handling stress change diurnally. Consistent with predictions, plasma CORT and GLU increased in response to capture and handling stress. Baseline levels of CORT and GLU did not change during the day, but the amplitude of plasma CORT increase (delta CORT) in response to capture decreased as Ta increased, as was the case for GLU, in birds with initially high baseline CORT. Neither baseline nor stress-related plasma CORT or GLU differed consistently across sampling locations. Both heat-shock cognate 70 (Hsc70) and heat-shock protein 90α (Hsp90) showed clear temporal dynamics across the day. These results indicate temporal plasticity of reaction norms during the day (Hsp) and in response to daily Ta changes, as well as to acute stress (CORT and GLU), but they provide little evidence for such plasticity in reaction norms across our geographical range.