Silky sifaka (Propithecus candidus) use sleep sites for thermoregulation, food access and predator avoidance

Primate sleeping site selection is influenced by multiple ecological factors including predation avoidance, thermoregulation, and food access. To test these hypotheses, we studied the sleeping trees used by a group of wild silky sifakas (Propithecus candidus) in Marojejy National Park, Madagascar. During this ten-month study, the group slept in 828 sleeping trees from approximately 35 genera. In support of thermoregulation, generalised linear models revealed that as temperature decreased, the number of individuals sleeping together significantly increased and they slept at further distances from the trunk. As rainfall increased, sleep site height significantly increased. Weinmannia was the most frequented tree genus, despite low abundance, accounting for 29% of all sleeping trees. In support of food access, 94.8% of sleeping trees were food trees. Weinmannia is among the most highly preferred food trees. The group slept at a mean height of 16.0 m near the top of tall trees which averaged 19.5 m. Sleep trees were significantly taller than trees in botanical plots within the sifaka’s home range. They never slept in the same trees on consecutive nights, and sleeping heights were significantly higher than daytime heights which is consistent with predation avoidance. Social sleeping in groups of two or three individuals (62.9%) was more common than solitary sleeping (37.1%). At such heights, huddling may increase vigilance and lessen the risk of predation by the fossa (Cryptoprocta ferox) while also reducing heat loss. These patterns suggest that silky sifaka sleep site choice is influenced by thermoregulation and food access in addition to predation avoidance. We suggest that understanding sleep site use can assist in conservation of species like silky sifakas by enabling researchers to find new groups, protect habitats with key tree species, and inform reforestation efforts.

Assessment of the threatened carnivore community in the recently expanded rainforest protected area Anjanaharibe-Sud Special Reserve, Madagascar

Madagascar is an island nation renowned for its biodiversity and species endemism, yet it is still largely understudied despite intense anthropogenic threats including forest loss and edge effects. Anjanaharibe-Sud Special Reserve is a recently expanded rainforest protected area that is lacking detailed surveys and assessments of the native carnivore community of the endemic family Eupleridae. To identify which terrestrial carnivores occupy the reserve and what anthropogenic disturbances and factors best explain their occurrence patterns, we deployed 35 motion-activated cameras to detect native and introduced carnivores. From November 2018 to February 2019, we collected 2918 unique capture events (all species) and confirmed the presence of 5 euplerids: Galidia elegans, Galidictis fasciata, Eupleres goudotii, Fossa fossana, and Cryptoprocta ferox. These results extend the known range of E. goudotii and G. fasciata. In the reserve, F. fossana and G. elegans were the most common and widespread native carnivores, while E. goudotii was the rarest. We highlight the negative impact of edge effects on G. fasciata and F. fossana and the threat posed by the free-ranging non-native carnivore C. familiaris. This study represents the first detailed survey and occurrence estimates of the carnivore community of this protected area, allowing comparison with other protected areas in Madagascar. Our empirical findings show that anthropogenic disturbance negatively impacts carnivore existence within the Anjanaharibe-Sud Special Reserve and provide important management recommendations for protecting the carnivore community and the co-occurring wildlife living within this area.

Temporal patterns of waterhole use as a predator avoidance strategy

Animals that depend on water sources in dry environments must balance their water demands with predation risk. In settings of water scarcity, predators may strategically exploit prey’s dependence on water; prey may adjust their use of water sources either spatially or temporally to avoid overlapping with predators. To examine the spatiotemporal dynamics of predators and prey at water sources, we studied the use of semipermanent waterholes in the dry season by red-fronted lemurs (Eulemur rufifrons), a primate species that exhibits flexible circadian activity patterns and inhabits a dry deciduous forest in western Madagascar. We hypothesized that lemurs avoid predators in their spatiotemporal use of waterholes. We analyzed the patterns of camera trap activations at waterholes by red-fronted lemurs and their two main predators: fossa (Cryptoprocta ferox) and Madagascar harrier hawks (Polyboroides radiatus). We found that red-fronted lemurs were unlikely to use waterholes at times of day when predators were commonly present, and that the distributions of times of waterhole use differed between red-fronted lemurs and each of their predator species. Red-fronted lemurs frequently used waterholes that were also used by predators within the same week in part because the predators used a variable set of water resources. In this system, predators did not appear to exploit waterholes for the high density of red-fronted lemurs attracted to them, but instead likely used waterholes primarily to meet their own water demands. Our findings suggest that when predators and prey share water sources, prey may adjust their behavior to reduce their risk of overlap with predators, including through avoidance of indirect cues of predation, such as waterholes at particular times of day.

Spatial dynamics and activity patterns of the fosa Cryptoprocta ferox in Ankarafantsika National Park, Madagascar: carnivores navigating a human-influenced landscape

The Vulnerable fosa Cryptoprocta ferox is the largest native carnivore in Madagascar, fulfilling a unique ecological niche in the island's remaining forests. Negative interactions with humans threaten the long-term viability of most remaining fosa populations across Madagascar. Threats to the fosa include habitat loss and persecution by humans resulting from perceived predation on domestic animals. We used GPS collars to record space use and activity patterns of five fosas in Ankarafantsika National Park, Madagascar, during the dry seasons of 2016 and 2017. The results, with up to 2,110 recorded locations per individual, indicated fosas’ home ranges and movements were not limited to the forest, and all collared individuals used networks of habitat patches and corridors to navigate deforested areas. The fosas studied in Ankarafantsika National Park had significantly larger home ranges than those reported in previous studies in other protected areas. They were rarely found within village boundaries and appeared to avoid areas of human habitation, suggesting that during the study period livestock was not a significant component of the fosas’ diet in this Park. Our results suggest that fosas have some flexibility that enables them to adapt to living near deforested and human-dominated areas by altering their space-use patterns, but they are compensating by increasing their home range size.

Effects of habitat alteration and disturbance by humans and exotic species on fosa Cryptoprocta ferox occupancy in Madagascar's deciduous forests

Anthropogenic habitat alteration and invasive species are threatening carnivores globally. Understanding the impact of these factors is critical for creating localized, effective conservation programmes. Madagascar's Eupleridae have been described as the least studied and most threatened group of carnivores. We investigated the effects of habitat degradation and the presence of people and exotic species on the modelled occupancy of the endemic fosa Cryptoprocta ferox, conducting camera-trap surveys in two western deciduous forests, Ankarafantsika National Park and Andranomena Special Reserve. Our results indicated no clear patterns between habitat degradation and fosa occupancy but a strong negative association between cats Felis sp. and fosas. Cat occupancy was negatively associated with birds and positively associated with contiguous forest and narrow trails. In contrast, dog Canis lupus familiaris occupancy was best predicted by wide trails, degraded forest and exotic civets. Our results suggest fosas are capable of traversing degraded landscapes and, in the short term, are resilient to contiguous forest disturbance. However, high occupancy of cats and dogs in the landscape leads to resource competition through prey exploitation and interference, increasing the risk of transmission of potentially fatal diseases. Management strategies for exotic carnivores should be considered, to reduce the widespread predation of endemic species and the transmission of disease.

A scale-dependent ‘functional’ assessment of the concept of endemism

Whether a species can be defined as ‘endemic’ or not is very controversial in theoretical terms, because the concepts of ‘endemism’ and ‘area of endemism’ remain much debated among scientists. We propose that it is necessary to consider the body size scale of an organism and the breadth of its distributional range if we want to define a given species as ‘endemic’ or not. Thus, for instance, Madagascar can be an appropriate area of endemism for animals as large and vagile as the fossa (Cryptoprocta ferox), but it is much too large to be considered an ecologically appropriate ‘area of endemism’ for small-sized frogs with limited dispersal abilities. Instead, for these small species it is ecologically more appropriate to consider given forest regions within Madagascar as ‘areas of endemism’. Therefore, we propose a five-step approach in order to define whether a given species can be considered endemic or not within a set of potential candidate species, and we offer a suite of practical examples (African squirrels, African Artiodactyla and a family of freshwater turtles from the Americas) to elucidate the designated concept. We define the new concept presented herein as ‘scale-dependent functional endemism’. The new concept has the benefits of including the ‘ecological characteristics’ of the target species in the concept of ‘endemism’ and being easily repeated, because it is based on rather objective criteria.