The influence of seasonality, anthropogenic disturbances, and cyclonic activity on the behavior of northern sportive lemurs (Lepilemur septentrionalis) at Montagne des Français, Madagascar

Abstract

Anthropogenic tropical deforestation and degradation imminently threaten primates today. Primates living in these disturbed habitats may also be subjected to increasingly severe tropical storms such as cyclones or hurricanes. These disturbances pose an immediate risk to their livelihood and can dramatically alter their habitats, in turn potentially shifting behavioral patterns. We had the unique opportunity to study the effects of seasonality, anthropogenic disturbances, and the immediate effects of a cyclone on the behavior of the critically endangered northern sportive lemur (NSL) in an anthropogenically disturbed forest in Madagascar. Cyclone Enawo made landfall on March 7, 2017 in northeast Madagascar with sustained wind speeds of 230 km/h. We collected behavioral data on nine individual NSLs during both wet and dry seasons, before and after Cyclone Enawo, and in areas of differing human activity, using scan sampling at 5-min intervals. We ran generalized linear mixed models to test the effects of seasonality and disturbances on behavior. We found that NSLs spent more time feeding in dry months compared with wet (Z = −4.21, p < 0.001). More specifically, they spent more time-consuming leaves and vine species in the dry season (Z = −2.26, p = 0.02; Z = −2.3; p = 0.02). We also found that NSLs were observed at lower heights in trees after the cyclone (Z = −2.45; p = 0.016) and spent more time in the interior portions of trees (Z = 3.44; p < 0.001), perhaps due to extensive limb damage of emergent trees documented after the cyclone. Our analyses show that seasonality affected most aspects of NSL behavior, followed by the effects of Cyclone Enawo, with anthropogenic disturbances having little effect.Our data suggest that the behavioral flexibility of NSLs in response to predictable seasonality may enable them to respond similarly to stochastic climatic disturbances.However, their generalist diet may allow them to persist in anthropogenically disturbed landscapes without the need to greatly alter their behavior.

Effects of forest fragmentation on the dietary ecology and activity of a nocturnal lemur community in North West Madagascar

“…As so many different habitat types are suitable for cheirogaleid lemur survival, it is therefore expected that these lemurs do not need to significantly alter most of their behaviors between them. In contrast, we had originally expected L. sahamalaza activity to vary between the two forests and between core and edge areas, as behavior for this species (Seiler, Holderied, et al, 2013b; Seiler et al, 2014) and other sportive lemur species (Dinsmore et al, 2016; Muir et al, 2019) often varies between habitat types and over habitat degradation gradients. Feeding activity of this species was significantly different among study areas, and time feeding appears to be significantly higher in the edge of Ankarafa forest (Figure 3) where less of this species' preferred food source of leaves may be available (Figure 2).…”

“…As we observed L. sahamalaza to eat food types other than leaves more frequently in Ankarafa, feeding niche breadth was higher in Ankarafa forest than in Anabohazo (Table 4, Supporting Information: File ). Sportive lemurs are primarily folivorous (Dröscher et al, 2016) but can adapt their diets to incorporate fruits when leaves of sufficient nutritional value are not available in times of environmental hardship (Dinsmore et al, 2016; Mandl et al, 2018; Seiler et al, 2014). Although our niche breadth indices therefore suggest that Ankarafa may have lower availability of good‐quality leaves, the diet of L. sahamalaza is flexible to enable its survival where its preferred food choice is not readily available.…”

“…sahamalaza activity to vary between the two forests and between core and edge areas, as behavior for this species (Seiler, Holderied, et al, 2013b;Seiler et al, 2014) and other sportive lemur species (Dinsmore et al, 2016;Muir et al, 2019) feeding appears to be significantly higher in the edge of Ankarafa forest (Figure 3) where less of this species' preferred food source of leaves may be available (Figure 2). However, the edge areas and degraded forest at Ankarafa have already been observed to provide sufficient food sources, sleeping sites, and shelter from predators for L. sahamalaza (Seiler, Holderied, et al, 2013a;Seiler, Schwitzer, et al, 2013;Seiler et al, 2014); the requirements of this species appear to be met within all of our study areas.…”

“…File 3). Sportive lemurs are primarily folivorous (Dröscher et al, 2016) but can adapt their diets to incorporate fruits when leaves of sufficient nutritional value are not available in times of environmental hardship (Dinsmore et al, 2016;Mandl et al, 2018;Seiler et al, 2014).…”

“…In addition to sharp population declines and geographic range contractions (Ganzhorn et al, 2000; Hending, Sgarlata, et al, 2020), forest fragmentation has been observed to cause changes in the behavioral ecology of many lemur species (Seiler, 2012). As with other primate groups, the responses of lemurs to fragmentation are species‐specific (Steffens & Lehman, 2018) and some species have had to increase foraging effort (Dinsmore et al, 2016; Gabriel, 2013), alter their activity patterns (Donati et al, 2016; Schwitzer, Kaumanns, et al, 2007) and stray from their regular diet (Donati et al, 2020; Seiler et al, 2014) to survive within fragmented landscapes. Conversely, some species have demonstrated high adaptability to forest fragmentation and degradation (Hending, 2021), and behavioral flexibility and plasticity of both diet (Donati et al, 2011; Eppley et al, 2017; Irwin, 2006) and activity (Cameron & Gould, 2013; Seiler et al, 2014) have been observed in multiple lemur species.…”