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Case Studies- Lemurs and Langurs. Note ecology of each species Male and Female social relationships. Ringtailed Lemurs Lemur catta. Best studied of the lemurs Inhabit dry forest of Madagascar. Social Behavior males. Live in large groups (for lemurs) 10-20.
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Case Studies- Lemurs and Langurs Note ecology of each species Male and Female social relationships
Ringtailed LemursLemur catta • Best studied of the lemurs • Inhabit dry forest of Madagascar
Social Behavior males • Live in large groups (for lemurs) 10-20. • Males migrate (in pairs often) • Lack consistent rank (rank reversals during mating) but high ranking males will mate often • No coalitions
Social Behavior females • More like anthropoids. Philopatric • Linear rank • Form matrilines • but don’t form coaltions • Rank can be stable but changes (hence labeled egalitarian!)
Omnivores (fruits and leaves mainly) Feeding behavior • Females when pregnant or lactating will eat (flowers, rare) or young leaves repectively (high in protein).
Ecology and Reproduction • VERY seasonal breeding (receptive 6-24 hours) • Early lactation = high fruit availability • Weaning coincides with a second fruit peak • Young leaves available throughout this reproductive time
Infant growth • Tied to season. Grow quickly in first 6-7 months of life, then slow down when food less available (drought potential)
Female dominance • Females dominant to males- Why?? • Physiologically stressed due to increased higher energetic costs compared to monkeys and apes. NOPE!!!! Ecologically stressed due to Madagascar habitat (smaller food sources, extreme environment). Possibly….
Within group Competition • Increased male-female aggressive behavior during Lacatation. Females have to be dominant to mediate competition from males. Sauther 1993
Hanuman Langurs Seminopithecus entellus • Legend of Hanuman
Research Koenig and Borries article in coursepak
Social Flexibility-males • Number of Males varies by group (uni-male. Multi-male. • Tenure about 27 months and males migrate when 2.5 years old (all-male bands). (But exceptions- Ramnagar site)
infanticide • Males can be highly aggressive with each other • Infanticide common in many populations
Not correlated with Predation (although in one population it did) Population density Habitat type Food : ( Social Grouping • Correlated with • # of females- how well males can monopolize them
Food • Used to be categorized as folivores (sacculated forestomach) • Truly seed eaters • New leaves, flowers, and fruit are eaten when available (phenology) • Mature leaves are a “fall-back” food • Insects (slow moving- caterpillars)
Ecology and Reproduction • Unprovisioned populations - breeding seasonal • During DRY season (not like the wet season for other primates) • Females at the poorest body condition when lactating!! • BUT high food availability occurs when conception occurs (cycle)
Provisioned populations • These have shorter inter-birth intervals, females breed earlier, faster growth. Provisioned n= 12 infants lifetime Unprovisioned N = 6 infants lifetime
Female relationships • Linear Dominance hierarchy • Philopatric, Matrilines • BUT…. • Not true of all populations • Matrilines important but not in all populations • Ranks not stable- so considered egalitarian • One population females disperse (Kanha)
Resident-egalitarian in some populations Dispersal- Egalitarian in others So category??? • Actually feed on monopolizable, defendable foods. • High ranking females are in better body condition than low ranking females • Competitive regime variable depending on season