Repeated Experimental Cold Exposure During Early Life Affects Several Metrics of Success but not Telomeres in a Common Songbird.

Climate change is increasing temperature variability and exposure to extreme temperature events, including cold snaps. Although there is evidence that exposure to cooler developmental temperature can have widespread phenotypic consequences, the degree to which temperature exposures might interact across developmental stages to affect offspring is poorly understood. Here we experimentally exposed free-living house sparrows to repeated bouts of parental absence, which cooled embryos and both cooled and deprived nestlings in a crossed design and examined the effects on growth, body mass, telomeres, and survival. We found that exposure to cooler temperatures during embryonic development had several negative consequences including extending incubation and reducing hatching success and body mass of recent hatchlings. However, there were no significant effects on telomeres. There were also no main effects of cooling and short-term food deprivation during post-hatching development or interactions across developmental stages on any developmental outcomes including telomeres. Taken together, these results suggest that some developmental stages and traits are more sensitive to repeated cooling than others. In songbirds, offspring may be more sensitive to repeated cooling at earlier life stages and telomeres may be largely resilient to these developmental insults.