Squealing rate indicates dominance rank in the male ring‐tailed lemur (Lemur catta)

Abstract

Squeals are sharp and forceful short-range vocalizations used as aggressive and submissive agonistic signals by many mammalian species. The ring-tailed lemur (Lemur catta), a female-dominant strepsirhine primate, has a male-specific squeal call with proposed male-male agonistic functions and male-female courtship functions that have never been empirically tested. The goal of my study is to clarify why ring-tailed lemur males squeal at other males and females by applying the handicap hypothesis to this male-specific vocalization. This hypothesis has rarely been tested in primates, and this study elucidates how the rate of a male-specific call relates to male-male and male-female behavior in a Malagasy strepsirhine. To test whether males squeal towards other males to assert dominance, I predict that male squealing rate is positively correlated with dominance rank. I further predict that male ring-tailed lemurs squeal at other males while engaged in agonistic interactions, and that squealing during an interaction is positively correlated with winning that encounter. To test whether males squeal towards females as a mate attraction signal, I predict that male squealing rate is higher on estrus days, and that estrous females indicate attraction by approaching squealing males. From March to July 2010, 480 hr of focal data were collected on 25 males aged three and older at Beza Mahafaly Special Reserve, Madagascar. I continuously observed each male for 30 min at a time and recorded all agonistic interactions and squeal vocalizations using 1-0 sampling at 2.5-min intervals. Squealing rate was higher during times of male-male agonism when compared to times without male-male agonism, and males with higher dominance ranks had higher squealing rates. In contrast, the mate attraction hypothesis was not supported. My results suggest that the male squeal is an agonistic signal when used in male-male interaction in ring-tailed lemurs, but does not specifically indicate aggression or submission.

Antipredator Vocalization Usage in the Male Ring-Tailed Lemur (Lemur catta)

“…Previous support for this hypothesis had been found in vervet monkeys (Chlorocebus pygerythrus) and tufted capuchin monkeys (Cebus apella) [Cheney and Seyfarth, 1985;van Schaik and van Noordwijk, 1989]. For some L. catta vocalizations, the vocalization rate is known to be correlated with individual male dominance rank [Bolt, 2013c[Bolt, , 2014, but alarm calls do not fit this trend. In contrast to primate species such as C. pygerythrus and C. apella , in which dominant males are thought to derive fitness benefits from calling at increased rates [Cheney and Seyfarth, 1985;van Schaik and van Noordwijk, 1989], dominant male L. catta may not alarm-call at higher rates because they may not receive any benefits from doing so.…”

Male-Specific Use of the Purr in the Ring-Tailed Lemur <b><i>(Lemur catta)</i></b>

“…One possible explanation involves consideration that in the ring-tailed lemur, male dominance ranks do not always remain stable throughout the annual breeding season [Koyama, 1988;Sauther, 1991;Gould 1994Gould , 1997Gould and Ziegler, 2007;Parga, 2009], which comprised part of my data collection period. In my study, high-ranking males who won agonistic interactions before and after the mating season did not win consistently throughout [Bolt, 2013c]. Purring could therefore be linked to dominance rank in general, rather than having a specific role as an assertive or submissive signal within agonistic interactions.…”

“…Rather, purring may have more to do with intrinsic qualities in individual males, which could make them more frequent vocalizers in all social contexts, ranging from agonism to affiliation [Bradbury and Vehrencamp, 1998]. Dominant ring-tailed lemur males do not have higher overall vocalization rates, but do have higher calling rates for some vocalizations used in agonistic contexts, such as the squeal [Bolt, 2013c] and purr. That the same purr vocalization is used in such widely ranging social contexts would seem to argue against it having distinct, informational functions in each situation.…”

Hunting and Nesting Phenology Influence Gobbling of Wild Turkeys

“…We offer that hunting potentially removes a segment of vocal males from the landscape while also prompting remaining males to reduce gobbling (Lehman et al , Chamberlain et al ), and in our study, cease gobbling well before the end of the reproductive season. Vocal males are theoretically more dominant individuals (Neumann et al , Bolt ), and removing them from the breeding population prior to peaks in onset of nest incubation could negatively influence fitness potential within the population (Ginsberg and Milner‐Gulland , Milner et al ). Likewise, our observation that remaining males in the population cease gobbling early in the reproductive season suggests that remaining males may adapt alternative reproductive strategies to secure breeding opportunities (Burk , Zuk and Kolluru , Hedrick ).…”