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Pulsed Squawk The pulsed squawk is a loud call commonly heard from the ruffed lemurs. Primatologists studying the black-and-white ruffed lemurs have suggested this call serves to warn conspecifics about nearby mammalian predators (Periera et al. 1988: 12; Morland 1991: 382), rallies the ruffed lemurs of a particular troop at night and establishes the troop's territory (Turner and Harrenstien 1985: 7), and punctuates abrupt roars (Morland 1991: 382). Observations of the red ruffed lemurs suggests that the pulsed squawk is used to indicate annoyance or is given when other lemurs are nearby (Hudson 2013). Works Cited: Hudson, Daphne. 2013. The Recording and Analysis of a Behavioral Vocal Repertoire for the Red Ruffed Lemur, Varecia rubra. Unpublished undergraduate thesis. Morland, Hilary S. 1991 Social organization and ecology of the black-and-white ruffed lemurs (Varecia variegata variegata) in lowland rainforest, Nosy Mangambe, Madagascar. Ph.D. Dissertation, Yale University. Pereira, Michael E., Martha L. Seelingson and Joseph M. Macedonia. 1988 The Behavioral Repertoire of the Black-and-White Ruffed Lemur, Varecia variegata variegata (Primates: Lemuridae). Folia Primatologica 51: 1-32. Turner, Mary-Elizabeth and Lisa Harrenstien. 1985 Loud calls of the ruffed lemur, Varecia variegata. Journal of the Elisha Mitchell Scientific Society 101(1): 1-8.
Contributed by Matilda Magatha Hudson
The Roar-Shriek Chorus The roar-shriek chorus is the most well-known loud call for this species of lemur. This incredibly loud call carries well across the forest, and is heard mostly in the mornings and evenings (Hudson 2013), but its exact purpose is not known. There are many different opinions on what purpose this call serves, and primatologists today are at a loss to explain how there could be so much variation of purpose in one animals' calls, and cannot say for certain which explanation(s) is (are) correct. In 1985, Mary Elizabeth Turner and Lisa Harrenstien argued that the "mob roar" (roar-shriek chorus) was an intra-group spacing indicator in wild ruffed lemurs, but an alarm call and indicator of stress in captive lemurs. At the time they conducted their study, there was debate among the community over whether this loud call exhibited sexual components. Turner and Harrentstien found no evidence to support this claim in their study. Michael Periera, Michelle Seeligson, and Joseph Macedonia (1988) studied captive black-and-white ruffed lemurs at Duke University and asserted the roar-shriek chorus was a sexualized call where the males shrieked and the females and juvenile males roared. Their observations led them to define the purpose of this chorus an an inter-group spacing mechanism. Hilary Morland (1991) observed the roar-shriek choruses of wild black-and-white ruffed lemurs occurring mostly after a male's squeal approach to another female (or vice versa), after a female acted aggressively towards a male, or during and punctuating other loud calls. In 2006, Thomas Geissmann and Thomas Mutschler neatly summarized the most commonly used explanations of the roar-shriek chorus today: 1. As an intragroup spacing function, 2. As an alarm function, 3. As a way to establish or defend territories, and 4. For intergroup coordination. After conducting a four day study on wild black-and-white ruffed lemurs, they concluded that all explanations are possible, except for the third. They discounted the suggestion that the call establishes and defends the troop's territory based on their observation that the calls occurred throughout the day. As this was a four-day study, their results cannot be entirely trusted. When discussing this topic, it is important to recognize several limiting and confounding features. First, all of these studies were performed only on the black-and-white lemurs. Second, these studies were most likely performed on different groups of lemurs (in different locations on the island of Madagascar), and on lemurs in different living environments (some were captive and living semi-free range lifestyles in the Duke Lemur Center). The functions of this call could vary from species to species and could have changed as lemurs adapted to new lifestyles in captivity or in different parts of the island.
Contributed by Matilda Magatha Hudson