The environment in which Propithecus verreauxi (common name: Verreaux’s sifaka) is found is highly seasonal, arid and frequently undergoes periods of drought. P. verreauxi compounds these challenges by giving birth during the dry season when resources are scarce. Considering lactation is the most energetically expensive reproductive stage, understanding how P. verreauxi females meet energetic requirements during periods of low resource availability is important. This study examines the behavior and diet of adult male and lactating female P. verreauxi to identify intersex differences. Continuous focal observations were completed at Berenty Private Reserve, Madagascar, over six weeks early in the birth season. The number of bites an individual consumed of an item was recorded along with the plant part and species. Intersex differences were largely nonexistent. Males and females did not differ significantly in regards to intake rate, the amount of total food consumed, and water intake. Females devoted a greater portion of time to feeding than did males but both sexes allocated similar amounts of time to resting. There were also no essential differences in amount of feeding time allocated to specific plant species and food types. Findings may suggest that P. verreauxi is a capital breeder, storing energy year-round. / Graduate / 0472 / 0329 / 0327

At least half of the world’s primate species are currently threatened with extinction. Slow life histories combined with rapid habitat loss and hunting in recent years has heightened the extinction risk for many species, including the two largest extant lemurs, the diademed sifaka (Propithecus diadema) and the indri (Indri indri). Both species belong to the taxonomic family Indriidae, have similar adult weights, and occur in sympatry in certain areas of the montane rainforests of eastern Madagascar. Both species are adapted for folivory however I. indri spend considerably more time feeding on leaves than do P. diadema resulting in several energy-saving adaptations in I.indri. In this dissertation, I explore infant development and maternal strategies of these critically endangered primates with the goal of increasing our knowledge of reproduction and ontogeny in both species. Although previous studies have elucidated key differences in adult behaviour, there is a dearth of information on infants and lactating females in either of these two species. Between June and December of 2011 and 2012, I collected continuous time focal animal data, in Maromizaha forest, to examine behavioural patterns of 12 infants and their mothers from 0 – 33 weeks. In addition, I developed a framework to define and quantify the weaning process and facilitate comparisons across different species and studies. P. diadema infants developed feeding competency and independent locomotion faster than did I. indri infants however both species were consistently feeding independently more than they were suckling by week 20. The process of feeding ontogeny in I. indri was likely accelerated by coprophagy, as all infants of this species consumed their mother’s feces regularly from 10 – 15 weeks old. Lactating females of both species spent more time feeding in mid-lactation when maternal investment was the highest. The prolonged inter-birth interval in I. indri is suggested as another adaptation that reduces energetic expenditures. In addition, the protracted period of close contact with their mother may offer infant I. indri more time for social learning of the mother’s diet and the group song and for developing competency in vertical clinging and leaping without a tail for balance and support. / Graduate

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