A comparison of nocturnal primate behavior in exhibits illuminated with red and blue light

• Published in: Applied animal behaviour science 2016-11, Vol.184, p.126-134
• Main Authors: Fuller, Grace, Raghanti, Mary Ann, Dennis, Patricia M., Kuhar, Christopher W., Willis, Mark A., Schook, Mandi Wilder, Lukas, Kristen E.
• Format: Article
• Language: English
• Subjects: Activity levels; Circadian disruption; Loris; Salivary melatonin; Zoo lighting design
• ISSN: 0168-1591; 1872-9045
• DOI: 10.1016/j.applanim.2016.08.011

•We experimentally changed the light color used to exhibit nocturnal primates at two zoos.•All study animals performed fewer active behaviors in exhibits with blue light compared to red.•Under blue light, concentrations of salivary melatonin decreased significantly in an aye-aye. Over evolutionary time, light from the sun, moon, and stars has provided organisms with reliable information about the passage of time; but modern artificial lighting has drastically altered these cues. Evidence is accumulating that exposure to light at night—particularly blue wavelengths—from computer screens, urban light pollution, or as an occupational hazard of night-shift work has major implications for human health. Nocturnal animals in zoos are generally housed on reversed light cycles and are illuminated by blue or red artificial light so that daytime visitors can observe their active behaviors. However, previous research suggests that exposure to light all 24h of the day and exposure to blue light during the dark phase can be harmful to human and animal health. Information about the consequences of lighting design for animal health and behavior is needed to formulate evidence-based guidelines for the exhibition of nocturnal animals in zoos. This study was conducted with nocturnal strepsirrhines at two facilities, one where the standard practice was to house nocturnal primates under blue light, and the other red. We experimentally changed the color of light illuminating habitats during the dark phase using an ABA study design and recorded continuous behavior data. We hypothesized that activity levels and time allocated to specific active behaviors would be lower under blue light compared to red. The overall percent of time spent performing active behaviors was lower when subjects were housed under blue light compared to red (generalized linear mixed models: pottos (N=4), F1,1169=54.0, p