Measured light/dark and activity/rest patterns in five species of lemurs Kenneth E. Glander1, Mariana G. Figueiro2, Geoffrey E. Jones2, Mark S. Rea2 1 Department of Evolutionary Anthropology, Duke University, Durham, NC 27708-0383 2 Lighting Research Center, Rensselaer Polytechnic Institute, Troy, NY 12180-3352 Introduction Results continued • Two kinds of light – visual and circadian Comparison of the two ruffed lemur species: black = activity; grey = circadian light stimulus • Human fovea peak spectral sensitivity is at 555 nm (CS); dotted lines demark astronomical sunrise and sunset. Note: the activity before sunrise • Human circadian peak spectral sensitivity is at 460 nm and after sunset; mid-day break in both activity and light intensity; different pattern of activity • Light is the primary synchronizer of all rhythms to the 24-hour solar day and light levels between ruffed lemur species; arrow-angles indicate Red ruffed lemurs had • Light/dark cycle’s role in shaping primate evolution is poorly understood more activity before light levels rose than did the Variegated black-and-white ruffed lemurs.a • Ancestral primate photic niche much debated • Nocturnal, cathemeral, diurnal • Light levels previously measured at observer’s location rather than animal’s location • New technology was used to measure proximal light exposure and the resulting activity pattern for individual animals Methods Study Site: Duke Lemur Center, Durham NC Technology: The Daysimeter-D measures proximate light/dark exposure patterns and associated activity/rest patterns and records data using on-board memory. The Comparison of outdoor (Left) and indoor (Right) housed male Ring-tailed lemurs’ light Daysimeter-Ds were mounted on exposure and activity patterns. Dotted lines demark astronomical sunrise and sunset. collars as pendants (See Subject Note: dramatically different light levels but similar activity patterns between outdoor and photos below). indoor individuals; both anticipated sunrise and continued activity after sunset; arrow- angles indicate that the outdoor individual (ID:250) had more activity after light levels dropped while the indoor individual (ID:248) had more activity before light levels rose.a Subjects: Four individuals of the following species wore the Daysimeter-D at the same time. Propithecus coquereli Eulemur mongoz Lemur catta Varecia variegata variegata Varecia rubra Coquerel’s Sifaka Mongoose lemur Ring-tailed lemur Variegated black-and-white Red ruffed lemur ruffed lemur Day/Night Activity Ratio for Five Species Procedure: Lower ratios indicate relatively more night-time activity • Individuals were hand-held while the 25 gram Daysimeter-D was attached to their collars. The individuals 2.8 were then returned to their normal social groups and housing. 2.4 2 • All four individuals of each species wore the Daysimeter-D for the same number of days, but test days for 1.6 any species did not overlap. 1.2 • Two of the four Ring-tailed lemurs were restricted to indoor rooms. 0.8 • The other two Ring-tailed lemurs and all others had access to indoor rooms, outdoor cages, or Natural 0.4 Habitat Enclosures (3-6 acres of Duke Forest). 0 Coquerel's Sifaka Mongoose Ring-tailed Variegated b-and- Red ruffed Results w ruffed • Lemurs have common and species specific light and behavior patterns • All are active sunrise to sunset Comments • All anticipated sunrise • There is no single “lemur” behavioral response or light exposure pattern. • All had a mid-day break • All five species are entrained to a diurnal niche, but there were distinct species • During this break the Red ruffed, Variegated black-and-white ruffed, and variations in light exposure levels and activity patterns. Mongoose lemurs experienced lower light levels than Ring-tailed lemurs and • This study is the first to measure individual behavior and proximal light exposure to Coquerel’s Sifaka. better understand primate photic niche adaptation. • Red ruffed lemurs were the only species not to reduce activity levels within an hour after sunrise • Indoor and outdoor Ring-tailed lemurs had similar activity profiles despite • Coquerel’s Sifaka were the only species not to be active after sunset dramatically different light level exposures. • They reduced activity 2 hours before sunset. • This technology will help improve lighting and thus management for captive • Ring-tailed lemurs had the highest average light level exposure primates. • Red ruffed lemurs had the lowest average light level exposure a Rea, M. S., Figueiro, M. G., Jones, G. E., & Glander, K. E. (2013). Daily activity and light exposure levels for five species of lemurs at the Duke Lemur Center. American Research funded by Journal of Physical Anthropology, 153(1), 68–77. doi:10.1002/ajpa.22409 .