Zebra finches (Taeniopygia castanotis) display varying degrees of stress resilience and recovery in response to constant light.

Traits vary in their ability to recover from stressors and is dependent on the magnitude, duration, or type of stressor. One such stressor is circadian rhythm disruption stemming from artificial light at night (ALAN). Circadian rhythm disruption may lead to long-term physiological consequences; however, the capacity in which individuals respond to recovery and display stress resilience is not known. Here, we exposed zebra finches (Taeniopygia castanotis) to constant light (24L:0D) or a regular light/dark cycle (14L:10D) for 23 days and a recovery period for 12 days. We measured body mass, corticosterone, and glucose levels before, during, and after constant light exposure and relative protein abundance of glucocorticoid receptors at death. In light-exposed birds, body mass significantly increased over time compared to birds under a regular light/dark cycle, but a 12-day recovery period reversed this increase. Baseline levels of circulating glucose decreased in light-exposed birds compared to controls, but significantly increased after the 12-day recovery period. In contrast, the glucose stress response did not show a similar recovery trend as body mass or baseline glucose in light-exposed birds. We did not detect any changes in baseline corticosterone or stress reactivity in both groups throughout the experiment. Lastly, we found higher protein abundance of glucocorticoid receptors in light-exposed birds at death. Our results indicate that physiological and morphological traits vary in their ability to recover in response to constant light and warrants further investigation on the mechanisms driving stress resilience under a disrupted circadian rhythm.