Dietary patterns of Propithecus diadema in the Maromizaha Forest

The diademed sifaka (Propithecus diadema) is a diurnal lemur inhabiting the eastern rainforests of Madagascar. This species is included in the IUCN Red List as "critically endangered" because it faces several threats, including habitat loss and poaching. This work aims to analyze the diet of a population of P. diadema in the Maromizaha New Protected Area. Data were collected from 2018 to 2022 for 314 sampling days on five habituated groups of wild sifakas. Thanks to natural marks and with the help of trained research guides, we could recognize each individual, who was identified by sex, rank, and age class. Spatial, behavioural, and feeding data were collected simultaneously. Behavioural data collection was performed using the focal animal sampling method. For each feeding session (i.e. each time the focal animal began to eat a portion of a plant) it was recorded the duration and ecological information, i.e., plant species, part of the plant consumed, and feeding height. I conducted spatial analyses using QGis software to obtain maps of groups' home ranges, seasonal distribution across the area, and spatial feeding patterns. I assessed seasonal variation by considering the duration of each feeding session at each GPS point, both in dry and rainy seasons. Moreover, I identified the most consumed food types (foliage, fruit, flowers) in terms of feeding duration and the number of feeding occurrences. I also indicated the ten most frequently eaten plant genera to allow further comparisons with previous studies. I found that the home range decreased in size during the rainy season. Accordingly, feeding is concentrated in specific locations, in contrast to what happens in the dry season. This could be due to the greater availability of food and, consequently, the lower inter-specific competition during the rainy season. Dietary results are consistent with spatial results showing seasonality of feeding. Although sifakas started fewer feeding sessions during the rainy season, they spent more time feeding on fruit and flowers, which are abundant in that period, compared to leaves. In contrast, sifakas feed more often during the dry season, when they eat more leaves in shorter sessions. I also found evidence of differences in feeding between age classes. Specifically, adults take longer feeding sessions compared to juveniles, who instead eat more often for a shorter time. Overall, sifakas consumed more than 60% of the genera Mendoncia and Eugenia in terms of feeding time spent and the number of occurrences. Studying the ecology and diet of endangered species like Propithecus diadema is crucial for their conservation and maintaining their ecosystems' health.