Prey selection and food habits of three sympatric large carnivores in a tropical lowland forest of the Eastern Himalayan Biodiversity Hotspot

Prey selection and the feeding habits of tiger Panthera tigris, leopard Panthera pardus and Asiatic wild dog Cuon alpinus were investigated from June 2009 to December 2011 in Pakke Tiger Reserve, Arunachal Pradesh. A total of 422 scats were analyzed of which, 109 scats were of tigers, 150 were of leopard and 163 scats were of dholes. Multinomial Likelihood ratio test was used to estimate the prey selectivity of predators and Ivlev index, Pianka index were used to estimate prey preference and overlap respectively. Biomass consumption for three sympatric predators varied from 254.3 kg for dholes to 599.1 kg for tigers. Sambar, barking deer, wild pig were preyed more than their availability by all the predators. Ivlev index shows barking deer and sambar were preferred more than available prey for tiger where as leopard preferred sambar more than available and avoided barking deer. Dhole preferred more than available wild pig and barking deer. There was a high overlap between tiger–leopard (85.3%) and tiger–dhole (77.5%). To the best of our understanding, this study provides the first reliable information on prey selection and food habits of sympatric large carnivores in a protected area of Eastern Himalayan tropical rainforest.     

Liana diversity and host relationships in a tropical evergreen forest in the Indian Eastern Ghats

In tropical evergreen forest in the Kolli Hills of the Indian Eastern Ghats, four 2 ha (100 m × 200 m) replicate plots (two plots each in undisturbed and human-impacted sites), were inventoried for species diversity of lianas 5 cm girth at breast height (g.b.h.) and their relationships with 30 cm g.b.h. host trees. Liana diversity included 26 species from 18 families and 24 genera. The population density and basal area of lianas in the study plots were 48 individuals ha^–1 and 0.23 m² ha^–1, respectively, while those of the trees were 478 stems ha^–1 and 43.6 m² ha^–1, respectively. As the lianas and their hosts had often been cut in the disturbed sites, their diversity was less there than in the undisturbed sites. Five (19%) liana species were common to all four sites. Three lianas, Hiptage benghalensis (Malpighiaceae), Elaeagnus indica (Elaeagnaceae) and Gnetum ula (Gnetaceae) were dominant. The twining mechanism (54% of liana species and 71% of individuals) and zoochorous diaspores (73% of species and 77% of individuals) predominated. A total of 336 trees from 39 species, 34 genera and 22 families hosted 345 lianas. The ratio of liana : host for species was 1 : 1.5 and for individuals was 1 : 1. Liana preferences for certain host trees, host girth classes and trellis heights were evident.     

Population densities,group size and biomass of ungulates in a lowland tropical rainforest forest of the eastern Himalayas

Large ungulate population monitoring is a crucial wildlife management tool as ungulates help in structuring and maintaining the large carnivore populations. Reliable data on population status of major ungulate prey species are still non-existent for most of the protected areas in the Indian part of the eastern Himalayan biodiversity hotspot. Twenty transects were monitored over a period of three years (2009–2011) totaling 600 km with an average length of 2 km. The estimated mean density of ungulates was 17.5 km⁻² with overall density of 48.7 km⁻². The wild pig Sus scrofa had the highest density (6.7 ± 1.2 km⁻²) among all the prey species followed by barking deer Muntiacus muntjak (3.9 ± 0.6 km⁻²), sambar Rusa unicolor (3.8 ± 0.5) and gaur Bos gaurus (3.5 ± 0.9 km⁻²). The estimated total ungulate biomass density was 2182.56 kg km⁻². This prey biomass can support up to 7.2 tigers per 100 km⁻². However, with two other sympatric carnivores sharing the same resources, the actual tiger numbers that can be supported will be lower. The estimated minor prey species was 31 km⁻² significantly 30.6% crop damages were reported by wild pig (p = 0.01) and 35.4% was elephant (p = 0.004). This data on ungulate densities and biomass will be crucial for carnivore conservation in this understudied globally significant biodiversity hotspot.     

Diet and prey profiles of three sympatric large carnivores in Bandipur Tiger Reserve, India

We conducted a field study of diets of three sympatric large carnivores, the tiger Panthera tigris , the leopard Panthera pardus and the dhole Cuon alpinus in Bandipur Tiger Reserve, India, based on analyses of 381, 111 and 181 scats, respectively. The frequency of occurrence of prey items in scats was converted to relative biomass and number of prey consumed using regression equations based on earlier feeding trials. The results showed that although these predators kill ∼11–15 species of vertebrate prey, relatively abundant ungulate species provide 88–97% of biomass consumed by them. Although the dietary niche overlap among the three species was high (Pianka's index of 0.75–0.93), some specialized predation was observed. The largest ungulates, gaur Bos gaurus and sambar Cervus unicolor , provided 73% of biomass consumed by tigers, whereas medium-sized chital Axis axis and wild pig Sus scrofa formed 65 and 83% of the biomass intake of leopards and dholes, respectively. In terms of the relative numbers of prey animals killed by the three predators, chital, which is the most abundant prey species, dominated their diets (tiger=33%, leopard=39% and dhole=73%). The results of the study, in conjunction with earlier work, support the prediction that abundance of ungulate prey species, as well as their availability in different size classes, are both critical factors that facilitate sympatry among the three predators.     

Tree diversity and population structure in undisturbed and human-impacted stands of tropical wet evergreen forest in Arunachal Pradesh, Eastern Himalayas, India

Tree species richness, tree density, basal area, population structure and distribution pattern were investigated in undisturbed, mildly disturbed, moderately disturbed and highly disturbed stands of tropical wet evergreen forests of Arunachal Pradesh. The forest stands were selected based on the disturbance index (the basal area of the cut trees measured at ground level expressed as a fraction of the total basal area of all trees including felled ones): (i) undisturbed stand (0% disturbance index), (ii) mildly disturbed (20% disturbance index), (iii) moderately disturbed (40% disturbance index), and (iv) highly disturbed stand (70% disturbance index). Tree species richness varied along the disturbance gradient in different stands. The mildly disturbed stand showed the highest species richness (54 of 51 genera). Species richness was lowest (16 of 16 genera) in the highly disturbed stand. In the undisturbed stand, 47 species of 42 genera were recorded while in the moderately disturbed stand 42 species of 36 genera were found. The Shannon–Wiener diversity index for tree species ranged from 0.7 to 2.02 in all the stands. The highest tree diversity was recorded in the undisturbed stand and the lowest in the highly disturbed stand. The stands differed with respect to the tree species composition at the family and generic level. Fagaceae, Dipterocarpaceae and Clusiaceae dominated over other families and contributed 53% in the undisturbed, 51% in the mildly disturbed, 42% in the moderately disturbed and 49% in the highly disturbed forest stands to the total density of the respective stand. Stand density was highest (5452 stems ha^–1) in the undisturbed stand, followed by the mildly disturbed stand (5014), intermediate (3656) in the moderately disturbed stand and lowest (338) in the highly disturbed stand. Dominance, calculated as the importance value index of different species, varied greatly across the stands. The highest stand density and species richness were represented in the medium girth class (51–110 cm) in all the stands. In the undisturbed stand, the highest density was found in the 111–140 cm girth class, while in the mildly disturbed stand the 51–80 cm girth range recorded the highest density. About 55, 68 and 52% species were found to be regenerating in the undisturbed, mildly disturbed and moderately disturbed stands, respectively. No regeneration was recorded in the highly disturbed stand. Variation in species richness, distribution pattern and regeneration potential is related to human interference and the need for forest conservation is emphasized.     

小相岭山系大中型兽类多样性的红外相机调查

区域的物种多样性监测和评估是制定保护和管理策略的重要基础。为评估小相岭山系大中型兽类多样性现状,于2018年1月至2020年11月,以区域内最具代表性的四川栗子坪国家级自然保护区和四川冶勒省级自然保护区为主要研究区域,采用红外相机公里网格陷阱法进行了调查 (n = 86台)。累计完成19 982个相机工作日,获得大中型兽类独立有效照片3 304张,共记录大中型野生兽类18种,隶属于4目12科。其中,国家一级重点保护野生动物有大熊猫 (Ailuropoda melanoleuca)、林麝 (Moschus berezovskii) 和金猫 (Catopuma temminckii);国家二级重点保护野生动物有亚洲黑熊 (Ursus thibetanus)、中华小熊猫 (Ailurus styani)、水鹿 (Rusa unicolor) 等10种,且水鹿为该区域的新分布记录。相对多度指数排名前五的种类分别是毛冠鹿 (Elaphodus cephalophus)、中华鬣羚 (Capricornis milneedwardsii)、野猪 (Sus scrofa)、黄喉貂 (Martes flavigula) 和猪獾 (Arctonyx collaris)。由于面积大小、海拔范围的不同,两个保护区在大中型兽类组成和相对多度方面存在一定的差异。放牧是小相岭山系两个自然保护区最主要的人为干扰。本调查为小相岭山系保护区大中型兽类及人为活动状况提供了基础数据,有助于保护区后续的保护和管理。     

Environment differentially affects the functional and phylogenetic structures of plant communities in a dry evergreen Afromontane tropical forest

Testing how local environmental conditions influence plant community assembly is important to understand the underlying mechanisms that promote and/or maintain biodiversity. Functional traits are used to find the broad spectrum of resource use strategies that plants use to respond to environmental variation. The patterns and drivers of plant community assembly through the lens of traits and phylogeny; however, remain to be studied in a uniquely biodiversity rich but poorly known fragmented dry Afromontane forest of Ethiopia. Here, we combined trait and community phylogenetic data from thirty sampling plots of 20 × 20 m size to determine the functional and phylogenetic structures and their drivers in a fragmented, human-dominated dry evergreen Afromontane forest. We found phylogenetic and functional clustering of plants in which the effect of environment was found to be trait specific. A weak phylogenetic signal for traits was detected suggesting that species resource use strategies may not be inferred using species phylogenetic distance. Additionally, we found functional traits to be weak in predicting species abundance distribution. Overall, while this study shows a non-random community assembly pattern, it also highlights the importance of deterministic processes being trait specific.     

Demographic aspects of sympatric Praomys jacksoni and P. stella in a tropical lowland forest in Kakamega, Kenya

Populations of coexisting tropical forest rodents Praomys jacksoni and P. (Hylomyscus) stella were investigated to test whether lower relative densities in regenerating forest compared with mature forest were because of poor health and/or reduced chances for females to breed. Relative frequencies, litter size, mass, length of embryos, presence or absence of ecto‐ and/ or endoparasites, and liver condition were recorded and analysed. Higher numbers of either species occurred in the mature compared with regenerating forest. Mottled livers and endoparasites were associated with heavier rodents; litter size related positively to mass of pregnant females in both species. Litter size, embryo size, sex ratios, liver condition, and infestation of ecto‐ and endoparasites were independent of forest and species. Apparently, reduced female density in regenerating forest had no breeding cost on individual females occurring there.     

Species number, species abundance and body length relationships of arboreal beetles in Bornean lowland rain forest trees

ABSTRACT.

• 1 The relationships between number of species, abundance per species, and body length are examined for 859 species of beetles in samples of arthropods collected from ten Bornean lowland forest trees by insecticide fogging. Similar relationships are examined for different feeding guilds of these beetles, and for those beetles from different species of trees.
• 2 The data are used to construct four interrelated graphs, namely species: abundance, species: body length, population abundance: body length and total number of individuals: body length distributions.
• 3 In contrast to a number of previous studies, no consistent linear relationship between population density and body length was found for the Bornean beetles and it is suggested that, as in birds, the added dispersal ability of flight reduces critical population densities necessary for persistence in small species. Previous relationships between body weight and population abundance may also be artefacts of the way in which data were gathered.
• 4 Despite large samples, we failed to locate the mode in plots of the number of species in each abundance category (species: abundance distribution).
• 5 Species: body length and total number of individuals: body length plots were similar to those found in previous studies, although using data for Coleoptera alone may have produced a steeper decline in the total number of individuals as body size increases than is apparent in samples of all arthropods.
• 6 We present the first three-dimensional graph relating numbers of species, body lengths and population abundances. The surface of this three-dimensional relationship is relatively simple.

     

Effect of prey availability on the abundance of White‐breasted Wood‐Wrens,insectivorous birds of tropical lowland forests

Some understory insectivorous birds manage to persist in tropical forest fragments despite significant habitat loss and forest fragmentation. Their persistence has been related to arthropod biomass. In addition, forest structure has been used as a proxy to estimate prey availability for understory birds and for calculating prey abundance. We used arthropod biomass and forest structural variables (leaf area index [LAI] and aerial leaf litter biomass) to explain the abundance of White‐breasted Wood‐Wrens (Henicorhina leucosticta), tropical understory insectivorous birds, in six forests in the Caribbean lowlands of Costa Rica. To estimate bird abundance, we performed point counts (100‐m radius) in two old‐growth forests, two second‐growth forests, and two selectively logged forests. Arthropod abundance was the best predictor of wood‐wren abundance (wi = 0.75). Wood‐wren abundance increased as the number of arthropods increased, and the estimated range of bird abundance obtained from the model varied from 0.51 (0.28 – 0.93 [95%CI]) to 3.70 (1.68 – 5.20 [95%CI]) within sites. LAI was positively correlated to prey abundance (P = 0.01), and explained part of the variation in wood‐wren abundance. In forests with high LAI, arthropods have more aerial leaf litter as potential habitat so more potential prey are available for wood‐wrens. Forests with a greater abundance of aerial leaf litter arthropods were more likely to sustain higher densities of wood‐wrens in a fragmented tropical landscape.     

Population density of primates in a large fragment of the Brazilian Atlantic rainforest

We performed a line transect survey (352.4 km) of primates in the Serra de Paranapiacaba, at one of the largest relatively undisturbed fragments of the Atlantic rainforest of Southeastern Brazil (ca. 1400 km²), in August 1998. The brown capuchin, Cebus apella nigritus, was the most common species found in the area (20 groups, density estimate: 5.31 ± 2.05 individuals per km², mean ± SE). Nine groups of the brown howler monkey, Alouatta guariba clamitans, and eight of the woolly spider monkey, Brachyteles arachnoides arachnoides, were also recorded, with preliminary density estimates of 0.79 ± 0.40 and 2.33 ± 1.37 individuals per km², respectively. Density estimates for these species in other fragments of Atlantic rainforest are reviewed, showing that densities in Paranapiacaba are among the lowest reported. It is suggested that the higher densities reported for isolated populations in small forest patches (<50 km²) is related to the absence of main primate predators, the density compensation phenomenon and the ecological plasticity of some primate species. In contrast, local extinction in many small patches is probably related to hunting pressure. Given the important primate populations found in the Paranapiacaba fragment, conservation strategies for the studied species should give priority to effective protection of the largest remnant fragments from illegal hunting and deforestation, rather than translocation of individuals or captive breeding programs to introduce monkeys in small forest fragments vulnerable to hunting and of uncertain future.     

Tree diversity and distribution in undisturbed and human-impacted sites of tropical wet evergreen forest in southern Western Ghats, India

The composition, abundance, population structure and distribution patterns of all woody species ( 30 cm gbh) were investigated in an undisturbed and two adjacent human-impacted sites of a tropical wet evergreen forest in Kalakad National Park, Western Ghats, south India. Three 1-ha plots were established, one each in (i) an undisturbed site (named site UD), (ii) in a site selectively felled 35 years ago (site SF – small stems felled leaving the large trees (as shade) for developing it into a cardamom estate, on the failure of which the site was abandoned) and (iii) a frequently disturbed site (site FD – round woods logged for use in ovens for curing cardamom). These sites are 1 to 3 km apart in the same wet evergreen forest. In the three study plots a total of 2150 stems (mean density 716 ha^–1) covering 122 species in 89 genera and 41 families were enumerated. Species richness was greatest (85 species ha^–1) in the undisturbed site UD, intermediate (83) in SF and lowest (80) in FD. Tree density was greatest (855 stems ha^–1) in site SF, intermediate (720) in UD and lowest (575) in FD. The forest stand was exceptionally voluminous in site UD (basal area 94.64 m² ha^–1), intermediate (66.9 m²) in SF and least (61.7 m²) in FD, due to tree removal for fuel in the latter sites. Species composition and abundance patterns markedly varied between the three sites. In UD and SF, primary forest species (Cryptocarya bourdillonii , Cullenia exarillata Myristica dactyloides etc.) occurred in greater density. In FD heliophilic secondary forest species (Elaeocarpus venustus, Litsea wightiana, Viburnum punctatum and Vitex altissima) were abundant, while these were absent in UD and SF. The species–area curve did not reach an asymptote in any of the sites on the 1-ha scale. The stand population structure was clearly reverse J shaped in UD and SF, while small stems were 2- to 3-fold fewer in FD. Most trees exhibited clumped distribution of individuals on the 1-ha scale. Variation in the kind and richness of species and their abundance is related to human interference and the need for forest conservation is emphasized.     

Plant biodiversity and conservation of tropical semi-evergreen forest in the Shervarayan hills of Eastern Ghats, India

Species diversity, density, population structure and dispersion patterns of all trees and lianas (30cm gbh) were inventoried in a tropical semi-evergreen forest in the Shervarayan hills of Eastern Ghats, south India. Such data are necessary for ecosystem conservation of the under-studied Eastern Ghats, as extensive forests here have already been converted to coffee and orange plantations and the landscape changed due to aluminium ore mining and quarrying. Four 1-ha plots were established in Sanyasimalai (SM) reserve forest of the Shervarayan hills, one plot (SM1) located close to mining and quarrying area, two other contiguous plots (SM2 and SM3) located in selective felling area and the fourth (SM4) in a relatively undisturbed forest. These are 1 to 4km apart in the same semi-evergreen forest tract. In the four study plots a total of 3260 stems (mean density 815ha–1) covering 80 species in 71 genera and 44 plant families were recorded. Species richness was greatest in the undisturbed plot SM4 (50), while lowest (33) in the selectively felled site SM2. The forest stand (SM4) was also denser (986 stemsha–1) and more voluminous (basal area 44.3m2ha–1 as compared with the site mean of 35m2ha–1) than the other plots. Four trees, Chionanthus paniculata, Syzygium cumini, Canthium dicoccum and Ligustrum perrottetii dominated the stand, collectively contributing to >50% of the total density. Species richness and stand density decreased with increasing tree girths. The forest stand contained a growing population, but there was considerable variation in basal area distribution between the plots. Trends in species population structure varied, particularly for selective-felled species. Most species exhibited clumped dispersion of individuals both at 0.25ha and 1-ha scales. Variation in plant diversity and abundance are related to site attributes and human impacts.     

Population size and density of Colobus vellerosus at the Boabeng-Fiema Monkey Sanctuary and surrounding forest fragments in Ghana

The Boabeng-Fiema Monkey Sanctuary (BFMS) is inhabited by a growing population of Ursine colobus (Colobus vellerosus), a species that is listed as vulnerable. Smaller, degraded forest fragments that surround the BFMS also contain C. vellerosus and may provide an important habitat for the monkeys. Our objectives were to 1) determine the current population size and density of C. vellerosus at BFMS and in five surrounding fragments, 2) examine the differences in demographics between the fragments and BFMS, and 3) determine whether a relationship exists between population density and fragment size and isolation distance from BFMS. The census was a complete count and was conducted for 1 month (July 2003) by S.W. and trained research assistants. Seven census routes were walked simultaneously on 13 days. The 2003 population estimate of C. vellerosus at BFMS was 217-241 individuals (15 groups), a slight increase from the 2000 census. Numbers in the fragments (58-62, six groups) have remained stable since 1997, when the only other census of these fragments was conducted. Mean group size did not differ between the fragments and BFMS. Larger fragments had larger numbers of colobus, but there was no relationship between fragment size and colobus density. Isolation distance had no effect on population density. Our data suggest that colobus probably travel between fragments. Conservation efforts should focus on treating the small forests and their connecting areas as a single conservation unit.     

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

Remotely sensed vegetation indices are increasingly being used in wildlife studies but field‐based support for their utility as a measure of forage availability comes largely from open‐canopy habitats. We assessed whether normalized difference vegetation index (NDVI) represents forage availability for Asian elephants in a southern Indian tropical forest. We found that the number of food species was a small percentage of all plant species. NDVI was not a good measure of food abundance in any vegetation category partly because of (a) small to moderate proportional abundances of food species relative to the total abundance of all species in that category (herbs and shrubs), (b) abundant overstory vegetation resulting in low correlations between NDVI and food abundance, despite a high proportional abundance of food species and a concordance between total abundance and food species abundance (graminoids), and (c) the relevant variables measured and important as food at the ground level (count and GBH) not being related to primary productivity (trees and recruits). NDVI had a negative relationship with the total abundance of graminoids, which represent a bulk of elephant and other herbivore diet, because of negative interaction with other vegetation and canopy cover that positively explained NDVI. Spatially interpolated total graminoid abundance modeled from field data outperformed NDVI in predicting total graminoid abundance, although interpolation models of food graminoid abundance were not satisfactory. Our results reject the utility of NDVI in mapping elephant forage abundance in tropical forests, a finding that has implications for studies of other herbivores also. Abstract in Kannada is available with online material.     

天童常绿阔叶林中常绿与落叶物种的物种多度分布格局

物种多度分布是对群落内不同物种多度情况的数量描述, 作为理解群落性质的基石, 其形成机制受到广泛关注。常绿与落叶物种是两类有着不同物候性状与生长策略的物种集合, 它们普遍共存于常绿阔叶林中。在天童20 ha常绿阔叶林动态监测样地内, 虽然常绿物种在物种多度和胸高断面积等指标上占有绝对优势, 但其在物种丰富度上却不及落叶物种。分析两者在常绿阔叶林中的物种多度分布特征, 能够为理解常绿阔叶林内物种多样性的维持机制提供一个全新的视角。为此, 我们基于天童样地的植被调查数据, 一方面利用累积经验分布函数对两类生活型植物的物种多度分布进行描述, 使用Kolmogorov-Smirnov检验(K-S检验)判断其差异性; 另一方面, 采用纯统计模型、生态位模型和中性理论模型对二者的物种多度分布曲线进行拟合, 并基于K-S检验的结果以及AIC值进行最优模型的筛选。结果显示: (1)常绿与落叶物种的物种多度分布曲线间并无显著差异。(2)在选用的3类模型中, 中性理论模型对于两类物种多度分布曲线的拟合效果都最好, 而生态位模型的拟合效果则一般。从上述结果可以看出, 尽管常绿与落叶物种在物种数量和多度等方面均存在差异, 但它们却有着近似的物种多度分布格局以及相近的多样性维持机制。然而, 鉴于模型拟合的结果只能作为理解群落多样性构建机制的必要非充分条件, 故而只能初步判定中性过程对于常绿与落叶物种的物种多样性格局影响更大, 却不能排除或衡量诸如生态位分化等其他过程在两类生活型多样性格局形成中的贡献。     

High abundance of Myriochele fragilis Nilsen & Holthe, 1985 (Polychaeta: Oweniidae) in the deep sea of the Eastern Mediterranean

An exceptionally high abundance of Myriochele fragilis Nilsen & Holthe, 1985 (Polychaeta: Oweniidae) is reported for the Ierapetra Basin in the Eastern Mediterranean Sea from depths of 4159 and 4260 m, representing the first record outside the Norwegian and Arctic Sea and extending the depth range by more than 1600 m. Specimens are described and compared to closely related species.