Closely-related to the lemur star of Zaboomafoo fame, Verreaux’s sifaka (Propithecus verreauxi) are internationally recognized for their characteristic dance-like gait. Their powerful legs allow them to seemingly defeat the laws of physics as they leap from one spikey tree to the next. While visitors to Madagascar and nature documentary watchers around the world recognize this endangered sifaka mostly for its interesting locomotion patterns, Verreaux’s sifaka are also one of the best-understood lemur species for their social behavior.

Because sifaka often do not thrive well in captivity, almost everything we know about the social behavior of Verreaux’s sifaka comes from one of four long term study sites located in southern and western Madagascar. When studying long-lived animals like primates, having long-term study sites (such as Gombe where Jane Goodall studied chimpanzees) is crucial to understanding their behavior and how they interact with their environment. For Verreaux’s sifaka, some of the long-term study sites have been following the same population for over 40 years, which amounts to several sifaka generations. Although many early studies consisted only of monitoring group composition [number of adult males, females, and infants], it quickly became evident that Verreaux’s sifaka were not your typical primate. At that time, it was thought that primate groups of the same species generally resembled each other in composition (although this belief is slowly changing [1]). In some of the first survey studies, researchers found that Verreaux’s sifaka groups greatly vary in terms of their group composition [2]. Some groups have multiple adult males and females, some only have a single male, some might just be a pair of adults and their offspring, and there can even be bachelor groups and floater males. This trend has been consistently documented at each of the other long-term study sites of Verreaux’s sifaka [3], [4], [5]; however, understanding why groups are so variable has proved more challenging.

Beyond their flexible grouping structure, the social lives of Verreaux’s sifaka have been relatively well-described. These animals’ social repertoire is particularly well-known compared to the other 110+ lemur species endemic to Madagascar. Like many other lemur species [6], Verreaux’s sifaka show female-biased power structures, more simply referred to as female dominance [7]. While in most primates, males are socially dominant to females, and thus gain priority of access to resources, Verreaux’s sifaka females show the opposite trend. Intersexual relationships become more complicated with alternative male reproductive strategies. Male Verreaux’s sifaka display one of two morphs (or forms): clean-chested or stained [8]. While there can be multiple males in a social group, only one male has a stained chest (male sifaka have a scent gland on their throat, which likely creates this stained appearance). Females mate more frequently with stained males [9]; however, clean-chested males do occasionally get a chance to mate during the limited breeding season. While clean-chested males get the short end of the deal in mating, they are groomed more by females than stained males [10], which may help reduce ectoparasite counts. The exact cost/benefit balance in this alternative reproductive strategy for both the stained and clean-chested males still remains to be seen.

Meredith Lutz is a PhD candidate in the Animal Behavior Graduate Group. She’s interested in behavioral plasticity and social behavior. Her current research focuses on drivers of social plasticity in primates, including Verreaux’s sifaka.

References:

[1] Strier, K. B., Henzi, S. P., Barrett, L., Martin, R. D., & Strier, K. B. (2009). Seeing the forest through the seeds: mechanisms of primate behavioral diversity from individuals to populations and beyond. Current Anthropology, 50(2), 213-228.

[2] Richard, A. (1974). Intra-specific variation in the social organization and ecology of Propithecus verreauxi. Folia Primatologica, 22(2-3), 178-207.

[3] Richard, A. F., Rakotomanga, P., & Schwartz, M. (1991). Demography of Propithecus verreauxi at Beza Mahafaly, Madagascar: sex ratio, survival, and fertility, 1984–1988. American Journal of Physical Anthropology, 84(3), 307-322.

[4] Springer, A., Mellmann, A., Fichtel, C., & Kappeler, P. M. (2016). Social structure and Escherichia coli sharing in a group-living wild primate, Verreaux’s sifaka. BMC ecology, 16(1), 6.

[5] Veilleux, C. C., Scarry, C. J., Di Fiore, A., Kirk, E. C., Bolnick, D. A., & Lewis, R. J. (2016). Group benefit associated with polymorphic trichromacy in a Malagasy primate (Propithecus verreauxi). Scientific reports, 6, 38418.

[6] Lewis, R. J. (2018). Female Power in Primates and the Phenomenon of Female Dominance. Annual Review of Anthropology, 47, 533-551.

[7] Richard, A. F., & Nicoll, M. E. (1987). Female social dominance and basal metabolism in a Malagasy primate, Propithecus verreauxi. American Journal of Primatology, 12(3), 309-314.

[8] Lewis, R. J., & van Schaik, C. P. (2007). Bimorphism in male Verreaux’s sifaka in the Kirindy Forest of Madagascar. International Journal of Primatology, 28(1), 159-182.

[9] Dall’Olio, S., Norscia, I., Antonacci, D., & Palagi, E. (2012). Sexual signalling in Propithecus verreauxi: male “chest badge” and female mate choice. PloS one, 7(5), e37332.[10] Lewis, R. J. (2008). Social influences on group membership in Propithecus verreauxi verreauxi. International journal of primatology, 29(5), 1249-1270.