This study investigates the physiological and behavioral effects of an annual after-hour lighting event, IllumiNights, on two captive Blue-throated Macaws (Ara glaucogularis) housed at Zoo Atlanta. As after-hour zoo events have been shown to affect animal welfare, this research aimed to assess whether such disturbances constitute a significant stressor for this critically endangered parrot species. Behavioral observations alongside fecal and feather corticosterone assays were conducted from September 2023 to March 2024 across three time periods, Pre, During, and Post IllumiNights. Results revealed individual differences in activity levels, with Miguel exhibiting significantly more active behaviors than Tulio. All-occurrence behaviors, such as vocalizations, allopreening, and social aggression, varied significantly with time, showing patterns consistent with transient stress and subsequent recovery. Fecal corticosterone concentrations significantly increased During and Post, suggesting an endocrine response possibly influenced by the event, seasonal environmental cues, or a combination of both. Feather corticosterone levels, however, did not significantly vary. These findings highlight the complex interplay between anthropogenic stimuli and biological rhythms in captive avian species. While IllumiNights elicited short-term behavioral and physiological changes, the event is unlikely to act as a major chronic stressor. The study contributes novel insights into avian welfare assessment in zoo settings and establishes baseline hormone data, with implications for ex-situ conservation and management practices.