The impact of forest logging and fragmentation on carnivore species composition, density and occupancy in Madagascar's rainforests

Abstract

Forest carnivores are threatened globally by logging and forest fragmentation yet we know relatively little about how such change affects predator populations. This is especially true in Madagascar, where carnivores have not been extensively studied. To understand better the effects of logging and fragmentation on Malagasy carnivores we evaluated species composition, density of fossa Cryptoprocta ferox and Malagasy civet Fossa fossana, and carnivore occupancy in central-eastern Madagascar. We photographically-sampled carnivores in two contiguous (primary and selectively-logged) and two fragmented rainforests (fragments , 2.5 and . 15 km from intact forest). Species composition varied, with more native carnivores in the contiguous than fragmented rainforests. F. fossana was absent from fragmented rainforests and at a lower density in selectively-logged than in primary rainforest (mean 1.38 ± SE 0.22 and 3.19 ± SE 0.55 individuals km −2 , respectively). C. ferox was detected in fragments , 2.5 km from forest and had similar densities in primary and selectivelylogged forests (0.12 ± SE 0.05 and 0.09 ± SE 0.04 adults km −2 , respectively) but was absent in fragments . 15 km from forest. We identified only two protected areas in Madagascar that may maintain . 300 adult C. ferox. Occupancy of broad-striped mongoose Galidictis fasciata was positively related to fragment size whereas occupancy of ring-tailed mongoose Galidia elegans elegans was negatively associated with increasing exotic wild cat (Felis spp.) activity at a camera site. Degraded rainforest fragments are difficult environments for Malagasy carnivores to occupy; there is a need to prioritize the reconnection and maintenance of contiguous forest tracts.

Modeling co-occurrence between toxic prey and naïve predators in an incipient invasion

“…This study helps to predict the extent of an incipient invasion in a top biodiversity hotspot and suggests considerable niche overlap between naïve native predators and a non- forest and appear to be highly sensitive to forest degradation and fragmentation (Gerber et al 2012c;Goodman 2012;Farris et al 2015b). Therefore, our finding that D. melanostictus may converge with five of the carnivores on the vegetation cover niche axis (a non-climate variable) is also of major concern; this suggests that the toad is capable of expanding beyond its current distribution in Madagascar, which for the moment remains within the urban area of Toamasina and nearby disturbed forests (Moore et al 2015).…”

“…Similarly surprising was the lack of observed niche overlap between D. melanostictus and C. ferox along NDVI and elevation axes, since the latter is one of Madagascar's most wide-ranging carnivores and is known to move through primary, degraded, and non-forest habitats (Hawkins 2003;Gerber et al 2012c). It is unclear whether this result is an artefact of the modeling technique (i.e., background test) or due to exclusion of relevant climate and environmental variables (see below).…”

“…Given the high niche overlap with D. melanostictus, such species nonetheless may be more likely to encounter the toad and potentially consume it. These two rare carnivores consistently have the lowest probabilities of occurrence across eastern rainforest habitats (Farris et al 2015b;Gerber et al 2012c) and the potential for additive mortality resulting from the consumption of D.…”

“…Certain species, such as E. goudotii, F. fossana, G. fasciata and S. concolor appear to confine their foraging to intact, primary forests, marshes and other aquatic habitats, and as specialists-for our purposes, defined solely by their environmental niche-tend to be restrictive in their habitat selection. They occupy a smaller or narrower range, depending on whether available habitats are threatened or resources are scarce (Gerber et al 2012c;Farris et al 2015b). In the case of S. concolor and G. fasciata, they are estimated to have a smaller initial population density compared to carnivores with wider environmental niches that are not restricted to intact forests (e.g., C. ferox, G. elegans).…”

Barking up the right tree: Understanding local attitudes towards dogs in villages surrounding Ranomafana National Park, Madagascar can benefit applied conservation

“…Exotic carnivores, particularly feral and/or domestic dogs represent a serious threat to wildlife worldwide given their ability to act as predators, disease vectors, and to influence trophic dynamics (Barcala 2009, Vanak and Gompper 2009, Young et al 2011, Weston and Stankowich 2013, Ritchie et al 2014, Farris et al 2015a. Recent research in Madagascar has highlighted the ability of these exotic carnivores to negatively affect native wildlife, including altering temporal activity patterns (Gerber et al 2012a, Farris et al 2015b) and spatial distribution (Farris et al 2015c) and reducing the probability of occupancy and detection for native carnivores (Gerber et al 2012b, Farris et al 2015b). In addition, Farris et al (2014) highlighted the negative interactions between exotic carnivores and lemurs (Microcebus rufus) across contiguous and fragmented forests, and point to a striking decrease in lemur occupancy at sites where exotic carni-SHORT NOTE http://dx.doi.org/10.…”