Abstract

The invasion of spotted deer (Axis axis) in the Andaman Islands, India, is a serious concern for the native flora and fauna of this insular ecosystem. We assessed how invasive spotted deer herbivory is affecting the regeneration and vegetation composition in the mangrove forest of the South Andaman Islands by comparing sites with and without herbivory pressure. Vegetation data was collected across 18 sites (ten sites with herbivory in the Mahatma Gandhi Marine National Park, and eight sites without herbivory (control) in South Andaman). We used circular plots (7m radius) along linear transects for data collection (125 plots each for herbivory site and control site). The results highlighted a strong influence of herbivory on mangrove vegetation and the impacts varied across the three mangrove zones (landward, ecotone, and seaward). Control sites consistently exhibited higher species richness and abundance across all categories (tree, sapling, and seedling) except for seedling abundance. Herbivory disturbance varied significantly along the three zones, (p < 0.05) with the landward zone being the most affected, followed by ecotone to seaward zones. Invasive spotted deer herbivory altered the vegetation structure and recruitment, especially in landward mangroves, leading to shifts in mangrove distribution and the emergence of the least palatable Ceriops tagal as the dominant species. Management and policy-level interventions are an immediate requirement for the removal of invasive spotted deer in the Andaman Islands for conserving mangroves and marine natural resources unique to the island ecosystem.

Keywords: Ceriops tagal, Invasive Alien Species, Mahatma Gandhi Marine National Park, Vegetation composition, Mangrove Recovery

Introduction

Invasive species significantly threaten local biodiversity, disrupt ecological functions, and outcompete native species (Mooney & Hobbs, 2000; Courchamp et al., 2003; Beltran et al., 2014). This negative interplay could lead to cascading impacts such as habitat loss, soil erosion, nutrient loss, reduced recruitment opportunity, and degradation of the whole ecosystem (Simberloff, 2011; Beltran et al., 2014; Russell et al., 2017). Particularly, the introduction of invasive herbivores can lead to changes in vegetation composition and a decline in species richness in the long term (Coomes et al., 2003; Webster et al., 2005). For instance, the invasive ungulate (Sus scrofa Linnaeus, 1758) introduced in the Great Smoky Mountains National Park, USA, altered the native vegetation through predation, habitat damage, competition, and disease transmission (Webster et al., 2005; McClure et al., 2018). The impact of invasive herbivory species on the island ecosystem is especially detrimental as most of the island species have evolved without intense competition due to herbivory and predation (Courchamp et al., 2003; Reaser et al., 2007; Picker, 2013).

The spotted deer Axis axis (Erxleben, 1777) was introduced in the Andaman Islands from mainland India by the British Government between 1914 and 1930 as a game animal (Ali, 2010; Mohanty & Ravichandran, 2017; Sandilyan et al., 2018). The invasive spotted deer have adapted and survived in the Andaman Islands for over 80 years due to a lack of predators. Studies have shown that spotted deer have caused severe degradation to the terrestrial vegetation by altering forest structure, limiting the regeneration potential of tree species, and decline in the understorey dwelling reptiles (Ali, 2006; Ali & Pelkey, 2013; Mohanty et al., 2013; Mohanty et al., 2016; Anujan et al., 2022). The impacts of invasive species on native biodiversity can intensify if the ecosystems have already faced degradation due to other factors (eg. anthropogenic stress, climate change, and drought). Particularly, the ecosystem that has experienced a large-scale disturbance event would find it difficult to recover with additional pressure from herbivory.

The 2004 Sumatra-Andaman earthquake (9.3 Moment magnitude) and the subsequent Indian Ocean tsunami had a profound impact on the coastal ecology and biodiversity across the Andaman and Nicobar Islands (Porwal et al., 2012; Nehru & Balasubramanian, 2018; Thirumurugan et al. 2022). Notably, the mangroves in these islands faced substantial challenges due to high-intensity tsunami waves, and land drowning or uplift due to tectonic slip (Nehru & Balasubramanian, 2018; Shiva Shankar et al. 2020). The land drowning and tsunami led to permanent inundation of seawater, resulting in the death of mangrove trees and ~50% (11.34 sq. km) loss of mangrove cover in South Andaman (Saxena et al., 2012; Shiva Shankar et al. 2020). Meanwhile, the subsidence also created new intertidal zones on the former terrestrial zones, which subsequently supported mangrove colonization (Nehru & Balasubramanian, 2018; Thirumurugan et al., 2022; Prabakaran et al., 2021). However, the natural recovery of the mangroves in the subsided sites of Andaman Islands is challenged by several natural (eg. propagules availability, edaphic factors, etc.), and anthropogenic barriers (eg. human trampling, land reclamations, and herbivory pressure, etc.). Particularly, the colonization or recovery of mangroves in the tsunami and subsidence-affected sites are subjected to herbivory by invasive spotted deer.

Post-2004 tsunami, numerous studies have focused on the degradation and subsequent recovery of mangroves in the Andaman and Nicobar Islands (Nehru & Balasubramanian, 2018; Shiva Shankar et al., 2020). However, the influence of herbivory by the invasive spotted deer on the mangrove colonization and recovery remain unstudied. In addition, the spotted deer populations faced no threat in the protected areas of the Andaman Islands, which is further likely to cause higher impacts in the national parks and wildlife sanctuaries compared to human dominated landscapes. Given that mangroves play a critical role in the maintenance of coastal biodiversity, climate regulation, local livelihood, and coastal protection, it is essential to conserve and manage the mangrove ecosystem (Feka & Morrison, 2017; Chow, 2018). Therefore, it is crucial to examine the effect of invasive spotted deer herbivory on mangrove vegetation. Hence our study focused on the following objectives: i) to understand the impacts of herbivory by invasive spotted deer on the mangrove vegetation composition, structure, and recruitment in South Andaman; ii) to deduce the palatability preference of spotted deer on the mangrove species; and iii) to enumerate the intensity of spotted deer herbivory along the different tidally influenced zones in mangroves. We compared sites with spotted deer herbivory and without spotted deer herbivory (control sites) to understand the impacts they exert on the regeneration and recovery of mangroves.

Material and Methods

Study area:

The Andaman and Nicobar Islands (ANI hereafter) in the Bay of Bengal form a curved submarine chain of the Arakan Yoma mountain range between Myanmar (Burma) and Sumatra. It constitutes 8,249 km2 of landmass with a 1,962 km coastline, exhibiting hotspots for endemism and rich biodiversity due to geographic isolation and unique ecological conditions (Sivaperuman et al., 2018). About 82% of land in ANI is designated as forestland, of which, mangroves occupy 7.5% (616 km2) contributing to 13% of India’s total mangrove cover (ISFR 2021). The ANI with 39 species of mangroves (Ragavan et al., 2015; Singh et al., 2024), is among the species-rich mangrove zones in the world.

The mangrove area in South Andaman covers approximately 189 km2 and comprises 30 mangrove species (Ragavan et al., 2015). South Andaman experiences a tropical hot, humid climate with high humidity throughout the year. Temperatures range from 18°C to 35°C on average, with an annual rainfall of up to 3500 mm (Dinesh et al., 2004; Yuvaraj et al., 2017). The natural vegetation primarily consists of tropical rainforests, rich in biodiversity and home to various fauna, including endemic and endangered species (Parkinson, 1923; Karthikeyan, 2017; Sivaperuman et al., 2021).

The Mahatma Gandhi Marine National Park (MGMNP), which is also known as the “Labyrinth Group of Islands”, is located on the south-western coast of South Andaman Islands (Soundararajan et al., 1997). The MGMNP consists of 15 vegetated islands, namely Alexandra, Belle, Boat, Chester, Grub, Hobday, Jolly buoy, Malay, Pluto, Redskin, Rifleman, Snob, Tarmugli, Twins, and parts of Rutland Island. The MGMNP with an area of 281 km2 is known for its rich biodiversity and endemism in flora and fauna — marine fauna, coral reefs, seagrasses, sandy beach, tropical evergreen forests, and luxuriant mangrove forests (Karthikeyan, 2017).

Sampling strategy:

The study was conducted in the South Andaman Islands from February 2022 to May 2023. A total of 18 sites were surveyed, comprising eight control sites (125 plots) in South Andaman with no spotted deer herbivory and ten sites (125 plots) from the highly protected MGMNP representing herbivory by invasive spotted deer (Figure 1). We used a linear transect method (Kauffman & Donato, 2012) in a mangrove patch that is 300 m – 350 m wide for vegetation data collection. The mangrove patches were divided into three zones- landward mangrove, ecotone mangrove and seaward mangroves (Figure 2). Three transects per site (minimum 50 m apart) were laid to cover maximum heterogeneity, starting from the landward edge (two plots), followed by the ecotone (two plots), and ending at the seaward edge (two plots) of mangrove forests (Figure 3). The placement of transects in the study sites was decided before visiting the site by exploring satellite images using “All-In-One” online maps application on an Android device. The circular plots (7 m radius) were placed along transects conforming to the mangrove zones start, middle, and end points. Tree (≥10 cm girth at breast height 1.3 m – GBH), sapling (≥ 1 to < 10 cm GBH), and seedling (< 1 cm GBH) were enumerated along with their species ID. In addition to the plot-based survey, each site was also randomly searched.

Figure 1: Spatial distribution of mangrove sites affected by grazing (Mahatma Gandhi Marine National Park – 10 sites) and not affected by grazing – control sites (South Andaman – 8 sites) Islands

Figure 2: Graphical representation of mangrove zonation in Andaman Islands.

Figure 3: Line Transect method showing six plots in a transect (which covers the Landward-Ecotone-Seaward species)

for species that are not present in the plots but present in the site. Each of the vegetation plots was ranked on a scale of 1 – 10 (low – high) for the intensity of herbivory pressure by spotted deer based on direct sightings and indirect evidence (for example: bite marks on leaves and pneumatophore, pellets, hoof marks etc.).

Data Analysis:

Ecological parameters such as species abundance, density, frequency, and relative values (of abundance, density, frequency) were calculated following the established principles (Curtis, 1959; Mishra, 1968; Greig-Smith, 1983) to understand the differences between the control and herbivory sites. The sum of relative values was used to calculate the Importance Value Index (IVI). The Shannon diversity index (H`) was calculated following the standard protocols (Shannon & Weiner, 1963). Variations in overall community composition among the three zones (landward, ecotone, and seaward) between the control and herbivory sites were analyzed using the Multiple Response Permutation Procedure (MRPP) by comparing the abundance data of vegetation cohorts (tree, sapling, and seedling) across the landward, ecotone, and seaward zones in each of the study site. In MRPP, the A values range between 0 and 1, where higher values indicate a more homogenous species composition and lower values a more heterogeneous species assemblage. We used the Bray-Curtis dissimilarity index in the MRPP to calculate the variations. Further, we analyzed the herbivory disturbance score between the sites and across the mangrove zones using the Kruskal-Wallis test. Later, Dunn’s post hoc test was conducted to identify pairwise differences between groups. All the analyses were conducted in the R-program (ver.4.2.3; R Core Team 2020); the MRPP analysis under the ‘vegan’ package (Oksanen et al., 2013) and Kruskal-Wallis test under the ‘dplyr’ package (Wickham et al., 2019). Heat maps were prepared to visualize the intensity of herbivory pressure at the study sites using the disturbance scores in QGIS software (Version 3.28). The disturbance scores ranging from 1 (indicating low herbivory pressure) to 10 (representing high herbivory pressure) were used.

Results

The species richness and abundance in the control sites were consistently higher across the cohorts (tree, sapling, seedling) than herbivory sites except for seedling (Table 1). Shannon diversity index varied across the cohorts, with control sites showing higher diversity in the recruitment layer (sapling and seedling) and herbivory sites showing higher diversity in the tree layer. The herbivory sites showed higer basal area than the control sites (Table 1).

The composition of mangrove species across the different zones showed varying results (Table 2). The species composition was not significantly different in the ecotone vs seaward zone across all the vegetation categories (p>0.05), except for seedlings in herbivory sites. The landward vs ecotone and landward vs seaward zones showed significant variation in species composition for trees and seedlings across the herbivory and control sites (p<0.05).

However, the sapling category showed a variation to this pattern, where it significantly varied in the control sites, while showed no significant variation in the herbivory sites (Table 2)

The top four dominant species were Rhizophora apiculata Blume, Bruguiera gymnorhiza (L.) Lam. ex. Savingy, Ceriops tagal (Perr.) C.B.Rob., and Avicennia marina (Forssk.) Vierh. the IVI values for the dominant species were nearly similar between the herbivory sites and

Table 1: Sampling effort and comparative species richness parameters of control & herbivory sites in Andaman Islands, India

Table 2: Details of Multiple Response Permutation Procedure (MRPP) conducted to understand the species compositional variation across the mangrove zones. Bray-Curtis dissimilarity index was used on the plot-wise abundance data collected from herbivory and control sites. Values of A range between 0 and 1, where higher values indicate a more homogenous species composition and lower values indicating a more heterogeneous species assemblage. P values represents the significance level of the observed dissimilarity between the groups.

control sites (Annexure 1 & 2). However, there were remarkable variations in the IVI values across the three cohorts of these species (Figure 4A & 4B). Particularly, Ceriops tagal was the most dominant species in the recruitment cohorts of the herbivory sites (Annexure 1.2 & 1.3). Most of the dominant species showed a reverse J-shaped trend in their demography with more individuals in the youngest size class (Figure: 4C, 4D, 4E) across the sites. Tree demography differed significantly between control and herbivory sites, particularly in the 10–30 cm and 31–60 cm size classes, where herbivory sites showed a decline in small trees and an increase in larger trees (91–120 cm, 120 cm, and above).

Of the 125 plots surveyed in the herbivory site, 67 % (n=84) of plots were impacted by herbivory, with 14% trees, 46% saplings, and 41% seedlings experiencing the herbivory. It is noteworthy that 33 % (n=41) of plots that were not affected by herbivory in the herbivory sites were mostly found in the ecotone zone (32 %) or seaward zone (51%). The landward zone exhibited the highest susceptibility to herbivory, with significant impacts observed on tree, sapling, and seedling populations. Specifically, herbivory has affected approximately 7% of mature trees, 99% of saplings, and 48% of seedlings within this zone (Figure 5A). The Kruskal Wallis test for the herbivory disturbance score (i.e. landward, ecotone, and seaward) revealed significant differences (p < 0.05), across the three zones (Figure 5B), indicating that all three zones have different medians.

Herbivory was observed in all the surveyed islands in MGMNP. Alexandra Island and Boat Island were severely impacted by the herbivory (Figure 6). All the plant parts including the leaf, apical shoots, branches, lenticels, pneumatophores, saplings, and seedlings (Figure 7 A-H) of the 25 true mangrove species (51 trees, 422 saplings, and 1009 seedlings) in the herbivory sites were grazed by the spotted deer. The exeocaeria agallocha L. and Avicennia marina trees were most disturbed and frequently grazed by the spotted deer. It was often observed that the entire area beneath these tree species was unvegetated without any recruitment, and even the pneumatophores (pencil roots) were grazed by the deer (Figure 7 A-H).

Discussion

Our study showed significant differences in species richness, composition, and diversity between control and herbivory sites in the mangrove vegetation across South Andaman Island, providing strong evidence of herbivory impact on the mangrove regeneration. The species richness (25–28 species), density (982–1349 individuals/ ha.), and diversity indices of the South Andaman Islands were similar to the earlier studies (Goutham-Bharathi et al., 2014; Ragavan et al., 2015; Shiva Shankar et al., 2020). In the control sites — characterized by no herbivory pressure — we observed higher species richness per plot across vegetation cohorts (tree, sapling, and seedling) compared to sites impacted by herbivory pressure. Minchinton et al. (2019) also observed similar patterns in vegetation structure and composition between areas with and without herbivores, particularly in tree density, girth class distribution, and sapling density. Further, the control sites were dominated by Rhizophora apiculata in all three categories, followed by the Bruguiera gymnorhiza and Ceriops tagal, which is similar to the previous studies from the Andaman Islands by Goutham-Bharathi et al. (2014), Ragavan et al. (2015), Shiva Shankar et al. (2020). Further, the herbivory sites having relatively lesser species richness in recruitment categories indicated negative influences of the herbivory pressure. Moreover, the control sites exhibited a higher abundance of trees and saplings than herbivory sites, signifying grazing, uprooting, and trampling by the spotted deer may have potentially caused the reduction in the tree/sapling abundance. Interestingly, herbivory sites showed higher cumulative basal area compared to control sites due to the presence of more large girth class trees. The high abundance of large trees in the herbivory sites could be due to the legal protection, and remoteness of these islands. The control sites in the South Andaman showed relatively lesser basal area and less number of large trees. This may be due to the history of

Figure 4: A&B. The dominant species in the Control site and Herbivory site; C&D. Demography of high abundance trees in control site and herbivory site; E. The demography of trees size class in both the sites F. Relative abundance of various size class of mangrove species most frequently preferred by the spotted deer

timber extraction and prolonged human influence on the mangroves of South Andaman Island. Meanwhile, the less diverse vegetation community structure in MGMNP suggests that the herbiivory reduce overall species diversity and structural complexity of the ecosystem (Robertson, 1991; Cannicci et al., 2008; Yessoufou et al., 2013).

The dominant species Rhizophora apiculata, Bruguiera gymnorhiza, Excoecaria agallocha, and Avicennia marina in the successional vegetation across the new intertidal areas were highly preferred by spotted deer in all the three mangrove zones. While they have shown least preference for Ceriops tagal. The IVI score of the Ceriops tagal in the control sites (tree – 8%, sapling – 20%, seedling – 18%) have significantly increased (more than two folds) in the herbivory sites (tree – 21%, sapling – 45%, seedling – 44%) indicating that this species is less palatable than most of the other mangrove species. Further, the palatability preference by the herbivores may cause a decrease in the relative densities of preferred plant species, and increase the non-preferred species (Barrett 2006). Hence, the selective herbivory of certain species would diminish overall diversity and structural integrity in the long run in mangrove ecosystems. The dominance of a single species promoted by

Figure 5: A. Intensity of herbivory by spotted deer across the three mangrove zones in the studied sites; B. Variations in the intensity of spotted deer herbivory among the three mangrove zones in the herbivory sites (Kruskal Wallis test and post hoc Dunn test).

Figure 6: Heat map indicating various intensities of spotted deer herbivory across various sites within the Mahatma Gandhi Marine National Park, Andaman Islands.

herbivory can lead to a drastic decline in the ecosystem services of mangrove forests such as carbon stock storage potential, and breeding and nursery ground for certain associated faunal species (Sarker et al., 2019).Mangroves store about 937 tons C ha-1 (Alongi, 2012) in general with the presence of species like Rhizophora spp., Bruguiera spp., and Avicennia marina; while Ceriops tagal dominant forests store less carbon stock (Komiyama et al., 2000; Raghbor et al., 2022). Therefore, the potential loss of carbon stocks may underachieve the potential for carbon sequestration in the mangroves of South Andaman (Hamilton & Friess, 2018; Alongi, 2020).

Following the 2004 large-scale natural disturbance, new intertidal zones were formed towards the landward zone in herbivory can lead to a drastic decline in the ecosystem services of mangrove forests such as carbon stock the subsided coastal areas of ANI, which provided the potential for mangrove transgression towards the landward zone (Nehru & Balasubramanian, 2018). Our study demonstrated aclear pattern where the herbivory pressure was significantly high in landward zone mangroves, compared to the ecotone and seaward zone (median value of herbivory score: 9>6>3).

We suspect that the high inundation resulting in less period of exposure, more loose soil substratum, and the complex root system of the Rhizophora spp. that dominate the seaward and ecotone zones are potentially limiting the spotted deer movement in the mangrove patches. Hence, the herbivory pressure has lower effect on the seaward zone and ecotone zones compared to the landward zone. Earlier studies from global mangroves have also reported the highest susceptibility

Figure 7: Impact of spotted deer herbivory on mangrove species. A. Bruguiera gymnorhiza propagule; B. Acrostichum aureum, a mangrove fern; C. exeocaeria agallocha, landward species; D. Phoenix paludosa, vulnerable species; E. Lumnitzera racemose; F. Pemphis acidula; G. Avicennia marina trees; H. Browsed pneumatophores of Avicennia marina and the denuded recruitment layer in the landward zone

of landward zone mangroves to herbivory pressure (Dahdouh-Guebas et al., 2006; Muhammad & Ahmed, 2008; Minchinton et al., 2019). Therefore, our study further confirms that the landward mangroves are highly susceptible to biotic pressure because they can be accessed immediately from the terrestrial zone and relatively provide favourable condition (eg. low water inundation providing longer period of accessibility, compact soil, and less complex root systems) to the herbivores compared to the seaward zones.

Woody plants usually form dense bush canopy as an adaptive strategy to increase their survival chances against herbivory pressure (Bee et al., 2007; Hoppe-Speer, 2012; Hoppe-Speer and Adams, 2015; Thirumurugan et al., 2022). Such a characteristic was especially observed among Lumnitzera racemosa, which is one among the dominant species in the landward zone. Additionally, it is observed that the leaves of Ceriops tagal were least preferred by spotted deer (only tender shoots). In Tarmugli and Hodbay Islands of MGMNP, the mud lobster (Thalasiana spp.) and crab mounds play a vital role in creating microhabitats for the establishment of saplings and seedlings of Avicennia marina species. It is likely that the complex mound structure is limiting the free movement of spotted deer and eventually reducing the herbivory on Avicennia marina (Minchinton, 2001).

Policy Intervention and Recommendation

Eradicating invasive species would improve the economic well-being of the local communities, including their cultural, health, and ecological values (Glen et al., 2013). In island ecosystems, eliminating invasive herbivore pressure can significantly recover floral communities within a few decades without any restoration interventions. For example, Beltran et al. (2014) reported that post herbivory eradication, 30% of barren land reversed to native woody vegetation in three decades. As indicated by Beltran et al. (2014), the herbivore removal would speed up regaining the ecosystem services lost and enhance soil stability due to increased mangrove cover and carbon storage. Further, the conservation of the mangrove ecosystem would ensure the conservation of other ecosystems like seagrass and corals that often benefits from the mangroves (Venkataraman, 2006; Gibson et al., 2007; Thangardjou & Bhatt, 2018; Gole, 2023).

The recent report by the Intergovernmental Science-Policy Platform on Biodiversity and Ecosystem Services (IPBES) highlighted concerns about invasive species in India that underlie the need for effective management strategies (Watson et al. 2019). India is a signatory of the global conservation initiatives like ‘Convention on Biological Diversity’ whose AICHI Target-9 (www.cbd.in) aims to identify and prioritize invasive alien species and pathways for their control or eradication and adapt measures to manage pathways to prevent their introduction and establishment. Therefore, eliminating spotted deer from the islands would be a crucial contribution to this target and allow both mangrove and terrestrial vegetation to regenerate quickly (Holmes et al., 2019). Spotted deer of the Andaman Islands is an efficient swimmer and spread from one island to another in search of suitable habitats and food resources. Therefore, efficient strategies needs to be devised for controlling the spread and increase of spotted deer population in the Andaman Islands.

Spotted deer are protected as Schedule-1 species under the Wildlife (Protected) Act, 1972 across India including ANI. However, island-specific alternative measures to control spotted deer population is need of the hour to minimize their impact on mangrove and terrestrial ecosystems (Ali, 2010). Several exemplary measures have been taken globally to effectively manage the invasive herbivore species. For example, invasive feral horses in Kosciuszko National Park, Australia, were removed through culling to mitigate the negative impacts of invasive species on the ecosystems (The Guardian, December, 2023). The recent 2022 Wildlife (Protection) Act Amendment, Section 62 A, and 62 B, epowers the managers to regulate the possession or proliferation of Invasive Alien species when they threaten wildlife or habitats in India. In line with this legislation, urgent measures (species removal) are required to address the proliferation of invasive spotted deer in the Andaman Islands, ensuring the preservation of native ecosystems and rich biodiversity in the Andaman Islands. Therefore, a policy-level change for a site-level intervention is crucial to eradicate the spotted deer population in the Andaman Islands.

Conclusion

The impact of herbivory on mangrove ecosystems is complex, particularly in the Andaman Islands, where the 2004 tsunami and subsidence have degraded mangroves and created new intertidal zones for re-establishment. Our study suggests that the invasive spotted deer herbivory has invariably affected the vegetation structure, particularly in landward mangroves, leading to a shift in mangrove composition. The impact of spotted deer herbivory on the mangrove ecosystem of Mahatma Gandhi Marine National Park (MGMNP) may drive diverse mangrove forests toward monodominant patches of Ceriops tagal, potentially altering habitat structure, ecosystem functionality, and increasing susceptibility to various consequences, including disease, pest infestations, and impacts on native fauna communities. Mangroves are the critical ecosystem that provide high economic benefits by regulating and conserving the coastal and marine biodiversity. It is noteworthy that the local economy and livelihood in the Andaman Islands is highly dependent on marine resources (eg. fish, crabs, prawns etc.). Therefore, immediate policy-level intervention is required for the eradication and management of invasive spotted deer in the Andaman Islands. Further, a baseline scientific information should be created on the intensity of spotted deer impacts on the ecosystem, and population density and distribution of spotted deer across the entire scale of Andaman Islands to guide the management intervention.

Acknowledgement

We thank the Department of Environment and Forest, Andaman and Nicobar Islands for the necessary permission and for facilitating the fieldwork. We are thankful to the Dean, Director, Faculties, and researchers of Wildlife Institute of India for the encouragement and constant support. We are acknowledge the support provided by Mr. Mayur Fulmali and our field assistants for their support during the fieldwork. We are thankful to the Head of the Department of Botany and the Principal of Madras Christian College (Autonomous) for providing facilities.

CONFLICT OF INTEREST
The authors have no competing interests to declare that are relevant to the content of this article.

DATA AVAILABILITY
The datasets generated during and/or analysed during the current study are available from the corresponding author on reasonable request.

AUTHOR CONTRIBUTIONS
V.T : Conceptualization; Methodology; Formal analysis; Investigation; Data Curation; Writing – Original Draft; Writing – Review & Editing.
A.R.S : Conceptualization; Writing – Review & Editing.
S.K : Methodology; Data Curation; Writing – Review & Editing.
G.G : Writing – Review & Editing.
N.P : Conceptualization; Methodology; Formal analysis; Resources; Writing – Original Draft; Writing – Review & Editing; Supervision; Project administration; Funding acquisition.