Factors affecting seasonal habitat use, and predicted range of two tropical deer in Indonesian rainforest

Overwhelming presence of non-food vegetation undermines the reliability of NDVI as a surrogate of forage abundance for a large herbivore in a tropical forest habitat

“…Moreover, simultaneous use of multiple remotely-sensed indices that are known to be correlated in deciduous forests (see Madugundu et al 2008) and arbitrary justification regarding what they represent (for example, leaf area index as a proxy of shade and NDVI as a proxy for food in Srinivasaiah et al 2012) makes it difficult to tease apart various effects such as food, human disturbance, and shade on habitat use. NDVI has been used as a proxy for resource availability or habitat quality in forest habitats in the case of other mammalian taxa such as primates (Papio hamadryas and Papio h. anubis from north-eastern Africa, Zinner et al 2001), ungulates (Axis kuhlii and Muntiacus muntjak from Indonesia, Rahman et al 2017), and arboreal marsupials (Petauroides volans, Petaurus breviceps, Pseudocheirus peregrinus, Trichosurus vulpecula, T. cunninghami from eastern Australia, Youngentob et al 2015) also, and field-based sampling of relevant vegetation in these habitats can validate how useful NDVI is in mapping of forage abundance.…”

“…We could find only a single such study in temperate forest (Borowik et al 2013) and one from a tropical forest habitat (Willems et al . 2009), despite the use of NDVI in studies of animal ecology in such habitats (Zinner et al 2001, Rood et al 2010, Srinivasaiah et al 2012, Marasinghe et al 2015, Lakshminarayan et al 2015, Rahman et al 2017). If remotely sensed indices do not actually reflect forage abundance, their use in studies of foraging and habitat use would lead to artefactual results.…”

NDVI is not reliable as a surrogate of forage abundance for a large herbivore in tropical forest habitat

“…However, while NDVI has been found to be a good surrogate of total vegetation biomass/primary productivity in various habitats (examples: savannahs: Sjöström et al., ; Wu, De Pauw & Helldén, ; savannah–steppe mixed landscapes: Sannier, Taylor & du Plessis, ; shrublands: Wilson, Silander, Gelfand & Glenn, ; tropical forests: Roy & Ravan, ; Madugundu, Nizalapur & Jha, ; Das & Singh, ), tests of whether NDVI or other similar indices actually reflect the abundance or quality of vegetation relevant to the focal animal are unfortunately rare and largely restricted to open habitats such as grasslands and savannahs (e.g., Kawamura et al., ; Ryan et al., ; Zengeya, Mutanga & Murwira, ). We could find only one such study in temperate forest (Borowik, Pettorelli, Sönnichsen & Jędrzejewska, ) and one from a tropical forest habitat (Willems et al., ), despite the use of NDVI in studies of animal ecology in those habitats (Lakshminarayanan, Karanth, Goswami, Vaidyanathan & Karanth, ; Marasinghe, Dayawansa & de Silva, ; Pokharel, Singh, Seshagiri & Sukumar, ; Rahman et al., ; Rood et al., ; Srinivasaiah, Anand, Vaidyanathan & Sinha, ; Zinner et al., ). If remotely sensed indices do not reflect forage abundance, their use in studies of foraging and habitat use would lead to artifactual results.…”

Large mammals and wetland utilisation: A case study in Yankari Game Reserve, Nigeria

“…Although wetlands are important habitats for sustaining animal populations, there is a widespread trend of increasing degradation of these habitats (Fynn, Chase, & Rӧder, ) and dearth of information pertaining to wetland utilisation in most PAs. While this is integral for effective conservation practice, few studies focus on this area in Africa (Arzamendia, Cassini, & Vila, ; Kumar, Mudappa, & Raman, ; Rahman et al, ). Here, we investigated the wetland utilisation dynamics of large mammals in Yankari Game Reserve (YGR).…”