Browsing by Author "Naniwadekar, Rohit"

Now showing 1 - 2 of 2

Effects of Local- and Landscape-level Drivers in Influencing Bird Diversity and Persistence in Cashew Plantations of the Northern Western Ghats
(Wildlife Institute of India, Dehradun, 2024) Madhu, Nandita; Jayapal, Rajah; Page, Navendu V.; Naniwadekar, Rohit
Agricultural expansion is a significant driver of deforestation and biodiversity loss, particularly in the tropics. The Western Ghats-Sri Lanka biodiversity hotspot is no exception. Most forest patches in the northern Western Ghats are being cleared for cashew cultivation. However, here, cashew plantations host varying proportions of cashew and native trees and have varying extents of ambient forest cover. Investigating the effects of such local and landscape-level drivers across land use types on taxonomic, functional, and phylogenetic diversities, as well as species- and trait-specific responses of birds, as implemented in this study, can give comprehensive insights on the impacts of forest conversion. I conducted this study in the low-elevation forests and cashew plantation landscape of Tillari, Maharashtra. I compared tree species diversity and vegetation structural attributes across land use types using Hill-Shannon diversity and linear models (LMs). To assess how land use type affects bird species composition and taxonomic diversity, I used non-metric multidimensional sampling (NMDS) and Hill-Shannon diversity. To compare functional and phylogenetic impacts across land use types, I used SES (Standardised Effect Size) values of fMPD (functional Mean Pairwise Distance) and pMPD (phylogenetic Mean Pairwise Distance) for LMs and Tukey’s post-hoc analysis. Using Hierarchical Modelling of Species Communities (HMSC), I looked for 1) bird species responses, 2) trait responses, and 3) a phylogenetic signal in the residuals. I collected bird and vegetation data from 100 points distributed across forest, mixed cashew plantations, and pure cashew plantations. My field collaborator (Vishal Sadekar) and I sampled vegetation within a 10 m radius of circular plots around all points. We sampled birds, implementing 10-minute point counts at a point, replicated 5 times across 4 months between January to May 2024. Vegetation differed significantly across all three land use types in terms of tree species diversity and tree height, where the forest had the highest estimates followed by mixed cashew. NMDS showed that the community in mixed cashew plantations overlapped with that of pure cashew plantations. There was no significant effect of land use type on functional diversity. But taxonomic and phylogenetic diversities were lowest in pure cashew. The HMSC model revealed a low explained variation (Tjur R2 = 0.1372), but I found land use type, a site-level variable, to exhibit the highest explained variation of 58% compared to the landscape-level variables. Forest species like Malabar Trogon (Harpactes fasciatus) and Black-naped Monarch (Hypothymis azurea) responded negatively to mixed and pure cashew plantations. Species like Golden-fronted Leafbird (Chloropsis auriforns) and Tickell’s Blue Flycatcher (Cyornis tickelliae) benefitted from mixed cashew and open country species like Indian Peafowl (Pavo cristatus) and Plain Prinia (Prinia inornata) responded positively to pure cashew. Trait response analysis revealed that evergreen species responded positively to the forest and negatively to both cashew habitats. Sedentary species responded positively to forest cover in 800 m. No evidence of a phylogenetic signal was found in the residuals (⍴ = 0.23, 95% CI: 0 - 0.68). This study highlights the value of mixed cashew plantations which are more habitable than pure cashew plantations due to native tree prevalence. However, this study also emphasises that even mixed cashew plantations cannot replace forests as habitats for evergreen forest species. This message is now more crucial than ever in the light of ongoing forest clearance in the northern Western Ghats.
Intra-specific variation in seed dispersal effectiveness of Lion-tailed Macaques Macaca silenus
(Wildlife Institute of India, Dehradun, 2024) Bindu, K.; Kumar, H.N. Dr. H. N. Kumara Dr. Navendu Page Dr. Rohit Naniwadekar; Page, Navendu V.; Naniwadekar, Rohit
1. Tropical forests are one of the most biodiverse ecosystems on Earth. Seed dispersal is one of the important interactions that maintains species richness and ecosystem functions. Vertebrate frugivores, especially birds and mammals, play a crucial role in dispersing seeds. The dispersal effectiveness of these dispersers is influenced by factors such as size, age, sex, dominance hierarchy and behaviour types. Invasive species pose significant threats to tropical ecosystems, rapidly forming mutualistic relations with native dispersers. This study focuses on the lion-tailed macaques Macaca silenus in the Western Ghats to explore how age-sex categories influence seed dispersal of native and exotic species in terms of diversity and quantity of fruits consumed, quantity of seeds dispersed, daily distance travelled and seed deposition site. 2. I employed non-invasive behavioural sampling on four troops of the lion-tailed macaques for four months. Focal animal sampling of 375.9 hours was employed on individuals belonging to three age sex categories, including adult males, adult females and subadults. Faecal samples were collected to assess quantity of seeds dispersed, and the substrate at seed deposition site was recorded. The movement of focal individual was tracked for the entire duration of the observation. 3. Subadults consumed higher diversity of fruits than females and males. Subadults also consumed more native fruits, while females consumed more non-native fruits. The pairwise dietary overlap between all age-sex categories was high. The rate of consumption of nonnative fruits increased as day progressed. Subadults dispersed significantly less Ficus seeds than the other age-sex categories. Daily movements showed no significant differences across age-sex categories. However, I found weak evidence of males being more likely to disperse seeds on trees, which could be more suitable for Ficus germination. The differences in 7 feeding patterns also highlight the greater importance of subadults in the dispersal of a greater diversity of fruit plant species. 4. The invasives Coffea spp. and Lantana camara constituted up to 90% of the diet of the three age-sex categories. There was difference in the relative proportions of these two species. Males consumed more Coffea spp., whereas subadults and females consumed more Lantana fruits. The macaques dispersed Ficus seeds in clumps, increasing the risk of predation or microbial infection. 5. This study generates novel information on intra-specific variation in seed dispersal, a relatively understudied topic. It also highlights lion-tailed macaques' significant role in dispersing alien invasive species in degraded rainforests and provides valuable insights into their understudied role as seed dispersers.