Seasonal differences in hair growth rates of captive aye‐aye, red ruffed, and black‐and‐white ruffed lemurs

Hair can be an important source of biological information, providing a record of such things as pollutant exposure, hormonal levels, and stable isotope ratios. Hair as a biological sample is easily accessible, easily stored, and resists degradation. Analysis of hair is particularly useful when studying rare and endangered species, such as lemurs, since it can be sampled noninvasively. However, to better interpret the results of stable isotope or other analyses, it is important to understand hair growth rates. We measured hair growth rates in captive aye‐ayes (Daubentonia madagascariensis), red ruffed lemurs (Varecia rubra), and black‐and‐white ruffed lemurs (Varecia variegata), both in winter (December 23, 2013, to January 13, 2014) and summer (July 10–31, 2013) at the Duke Lemur Center. Hair growth per week in all three species of lemurs differed significantly between the boreal summer and boreal winter. The aye‐aye, black‐and‐white ruffed lemur, red ruffed lemur had a mean weekly hair growth of 0.195, 0.209, and 0.232 cm, respectively, in the summer. While the aye‐aye, black‐and‐white ruffed lemur, and red ruffed lemur had a mean weekly hair growth of 0.239, 0.464, and 0.479 cm, respectively, in winter. We found no effect of age on hair growth rates, neither in the boreal summer, nor in the boreal winter for black‐and‐white ruffed lemurs and red ruffed lemurs. A pregnant black‐and‐white ruffed female displayed negligible hair growth during the northern winter, suggesting that pregnancy may affect the partitioning of resources away from such things as hair growth. Winter hair growth rates were significantly greater than summer hair growth rates for all three species studied. Black‐and‐white ruffed lemur and red ruffed lemur hair growth rates did not differ but were greater than the hair growth rates of aye‐ayes. Research Highlights Black‐and‐white ruffed lemur and red ruffed lemur hair growth rates did not differ but were greater than the hair growth rates of aye‐ayes. Season significantly affects hair growth rate for all three species. Age does not affect hair growth rates of black‐and‐white ruffed lemurs. Pregnancy may decrease hair growth rate.