Zebra Finch on a Rollercoaster: How Temperature Fluctuations Affect Physiology, Learning, and Memory

Climate variability and unpredictability present animals with challenging physiological and behavioural demands. However, empirical studies on endotherms involving manipulated environmental variability remain limited. This study investigated the impact of temperature variability during both development and adulthood and the effect of the mismatch between the conditions experienced at these two stages on physiological responses and learning performance. Initially, zebra finches ( Taeniopygia castanotis ) were subjected to two contrasting early life conditions: stable or variable ambient temperature conditions during early development and as juveniles. We assessed the colour-associative learning performance of juveniles (52–62 days old) and measured their accumulated feather corticosterone (fCORT) levels at approximately 80–95 days of age. Our results show that birds exposed to variable temperatures during development had higher fCORT levels and lower latency to choice in the learning test than those in stable conditions. However, we found no effect of temperature treatment or fCORT level on associative learning performance, as birds under all temperature conditions performed equally well in the tests. Furthermore, higher fCORT levels led to lower participation rates in those tests. We then randomly assigned half of each family's offspring to the opposite conditions after independence (95 days old) and evaluated whether developmental fCORT levels affected memory retention and adulthood learning. The activity levels of adult birds differed from those of juveniles and were affected by the mismatched temperature environment. The birds that moved from stable to variable conditions presented increased activity. Contrary to our prediction, memory retention was high across treatment groups. Based on our findings, temperature variability does not impact learning or memory. However, it directly influences activity levels and indirectly affects behaviours through changes in physiological response.