Malaysian Rain Forest Research Articles

Bat Species Diversity in the Merapoh Rich Limestone-rich Area within Lipis National Geopark, Malaysia.

Merapoh, Pahang, is an area rich with limestone karst located within the Lipis National Geopark and home to the Sungai Relau gate of Taman Negara Pahang, a totally protected rainforest in Malaysia. Much of the research conducted here is mainly inside the National Park, with few published faunal records for the Merapoh caves. This study compiled the data on the bat species diversity of eight Merapoh caves (March 2020 to March 2022) using mist nets and harp traps. Our results indicate that Chiroptera diversity at Merapoh caves is rich, with a total of 32 species recorded from 865 individuals and four new locality records for the State of Pahang, namely Rousettusleschenaultii, Lyrodermalyra, Rhinolophuscoelophyllus and Hipposiderospomona. Gua Gunting has the highest diversity of bats recorded in this study (19 species). Significant Merapoh caves with bat colony roosts in Merapoh include Gua Jinjang Pelamin (Eonycterisspelaea & Rousettusleschenaultii), Gua Tahi Bintang (Hipposideroslarvatus) and Gua Pasir Besar (Miniopterusmedius). Rhinolophusconvexus, previously recorded only in upper montane rainforests, was also recorded in Merapoh caves indicating that this species can also be found in lower elevations than previously thought. Based on the findings of the current study and additional records from two previous studies, the Merapoh bat species diversity checklist totalled up to 38 species. On the whole, the rich bat diversity in Merapoh is reflective of its immense limestone karst landscape, which highlights the reason Lipis National Geopark has been recently gazetted. Future bat research should continue here and in other karsts within Lipis Geopark to sustainably conserve biological diversity, manage geological structures and raise awareness amongst the locals to appreciate their national heritage.

Divorcing the dead, sharing with Others: negotiating alterity at the edges of a Malaysian rainforest

AbstractThis article explores how people formulate alterity as a responsive endeavour as they seek to live well in a context of profound marginality at the edges of a Malaysian rainforest. It argues that Batek people often narrate, encounter, and enact alterity – drawing distinctions between themselves and Others – through and in relation to acts of sharing. By exploring a diverse set of instances in which decisions about how and whether to share produces moments of tension, this article investigates the conditions of alterity that underlie sharing's very possibility. This involves asking not only how alterity is produced among Batek people, but also how it is extended outwards, both to those Batek term gɔp (outsiders), and to the dead people who continue to intrude in their lives. Through tracing these everyday moments where alterities are worked out between Batek and gɔp, and the living and the dead, it becomes apparent that as people encounter often‐unpredictable Others, an attitude of what Renato Rosaldo calls ‘social grace’ comes to the fore. Retheorizing alterity in the light of ‘social grace’ demonstrates it to be a responsive, indeterminate process of managing detachment and connection through the immediacy of the diverse encounters and ruptures of everyday life.

Attention-Based Semantic Segmentation Networks for Forest Applications

Deforestation remains one of the key concerning activities around the world due to commodity-driven extraction, agricultural land expansion, and urbanization. The effective and efficient monitoring of national forests using remote sensing technology is important for the early detection and mitigation of deforestation activities. Deep learning techniques have been vastly researched and applied to various remote sensing tasks, whereby fully convolutional neural networks have been commonly studied with various input band combinations for satellite imagery applications, but very little research has focused on deep networks with high-resolution representations, such as HRNet. In this study, an optimal semantic segmentation architecture based on high-resolution feature maps and an attention mechanism is proposed to label each pixel of the satellite imagery input for forest identification. The selected study areas are located in Malaysian rainforests, sampled from 2016, 2018, and 2020, downloaded using Google Earth Pro. Only a two-class problem is considered for this study, which is to classify each pixel either as forest or non-forest. HRNet is chosen as the baseline architecture, in which the hyperparameters are optimized before being embedded with an attention mechanism to help the model to focus on more critical features that are related to the forest. Several variants of the proposed methods are validated on 6120 sliced images, whereby the best performance reaches 85.58% for the mean intersection over union and 92.24% for accuracy. The benchmarking analysis also reveals that the attention-embedded high-resolution architecture outperforms U-Net, SegNet, and FC-DenseNet for both performance metrics. A qualitative analysis between the baseline and attention-based models also shows that fewer false classifications and cleaner prediction outputs can be observed in identifying the forest areas.

Species richness and phytogeographic affinities of rattan genus Korthalsia in Malaysia

Abstract. Shahimi S, Jamaludin AA, Ahmad A. 2023. Species richness and phytogeographic affinities of rattan genus Korthalsia in Malaysia. Biodiversitas 24: 5764-5778. The clustering climbing palm genus Korthalsia Blume (Arecaceae: Calamoideae: Calameae) is widespread in the Malesian region with 28 documented species. However, as many as 18 species are available in Malaysian rainforests. An inquiry was carried out in 2019 throughout Malaysia that included species richness and phytogeographic affinities for Korthalsia. Currently, Korthalsia is highly diverse in Sabah and Sarawak, with 15 species documented in this region, whereas 9 species are present in the Malay Peninsula. Species of Korthalsia were dominated by Korthalsia echinometra Becc., Korthalsia flagellaris Miq., Korthalsia hispida Becc., Korthalsia rigida Blume, and Korthalsia rostrata Blume, which suggests their prevalence in richness compared to being diverse; only 5 species found in all regions. The species accumulation curve indicates that this region's rattan community is moderately rich. There is an east-west separation for the distribution of rattan species in Peninsular Malaysia. This work's novelty reflects a new record for the distribution of K. hispida in Penang that indicates reductions in occurrence for known distributions. Perhaps underscores on significance and inadequacies related to continuous monitoring were responsible for efforts to develop a comprehensive understanding of the diversity, distribution, and potential discoveries for Korthalsia. This indicates risks from development because accessibility is improved and allows researchers to reach further terrain that previously could not be explored. However, despite this weakness, a correct checklist should be constructed for existing rainforests so Korthalsia dispersal, diversity, and richness can be correctly archived.

Comparative Diversity of Bats in Two Contrasting Habitats in Terengganu

Differentiations in the habitat and resource utilisation lead to segregation and specialisation of niches for bats within the structurally complex tropical rainforest in Malaysia. This research aims to characterise chiropterans’ assemblages found in two different habitat types in Tasik Kenyir (dipterocarp forest) and Setiu (oil palm plantation). A total of 48 sampling nights were conducted within two years period from March 2017 to March 2019 which covered four sampling sites in Tasik Kenyir and four sites at Setiu. Two standard four-bank harp traps and 10 mist nets were deployed throughout the study at every site to capture bats at understory levels. This makes a total of 576 sampling efforts for both areas. Song Meter SM2bats and Echo Meter Touch from Wildlife Acoustic were used to record the echolocation of insectivorous bats. The total number of individuals and species observed were used to determine species diversity, richness, and evenness. Paleontological statistic software was used to generate the rank abundance and species accumulation curves. Bray-Curtis similarity index was used to generalise the index that represents the relative abundance of the sampling sites. A total of 835 individuals comprising 31 species from six families were captured at both study areas. Out of 835 individuals, 695 were captured within Tasik Kenyir comprising 27 species from six families (H = 2.381) while 140 individuals were captured in Setiu comprising 20 species from five families (H = 2.40). The diversity of bats in Tasik Kenyir was hypothesised to be higher than in Setiu as the habitat possess a larger undisturbed forest. However, the result showed the opposite in which no significant difference was detected from the diversity index calculated between these two areas. Detailed studies need to be conducted to determine if some areas are used as transient habitats for bats.

A Walk Though the Rain Forest by Martin Jenkins

Reviewed by: A Walk Though the Rain Forest by Martin Jenkins Elizabeth Bush Jenkins, Martin A Walk Though the Rain Forest; illus. by Vicky White. Candlewick, 2022 [48p] Trade ed. ISBN 9781536211207 $18.99 Reviewed from digital galleys R 5-8 yrs Considering the forest here is the Taman Negara tropical rainforest in Malaysia, the titular walk promises to be an intriguing one. Readers know a lot of animals [End Page 51] live here, and Jenkins can enumerate a great many of them: "Ten kinds of owls, nine kinds of hornbills, eighteen kinds of woodpeckers." Some, however, he can't: "Goodness knows how many kinds of beetles (I certainly don't)." Those animals, spread out and well hidden, aren't easy to spot, so observers have to listen rather than simply look when carefully studying the trees. Jenkins highlights a puzzle: "All the trees here are big and old. There are no small, young ones." So, how does the rainforest keep itself going? The focus turns now to gathering clues: a fig tree where lots of animals feast; fig seeds broken open on the ground; trees too dense to admit much sunlight; piles of animal poop in a clearing; seeds in the poop; nutrients in the poop: "This is how it works: … When the animals poop, with luck they'll poop out some seeds somewhere good to grow." Jenkins' easy, conversational tone, and White's stunningly photorealistic paint and pencil mise en scène transform the shadowy, unfamiliar rainforest into an inviting milieu—wondrous but not too mysterious for a primary schooler to begin to grasp. A map, supplemental information, thumbnails of animals lurking in the illustrations, an index, and a brief resource list are included. Copyright © 2022 The Board of Trustees of the University of Illinois

Exploring the predation of large land snails using preyed shell remains from rock anvil sites in a tropical limestone rainforest in Malaysia.

The study of prey-predator interactions between land snails and birds offers important insights into evolutionary and ecological relationships. Here, we report a case study of rock anvils presumably used by the birds Myophonuscaeruleus and Enicurusruficapillus in a cave cavity of a limestone hill in Malaysia. We did not detect any other species in the plots and, therefore, based on our short study duration, we cannot rule out the possibility that other species, such as mammals, preyed on the snails. The predated shell remains of four land snails namely, Hemiplecta sp., Cyclophorusperdixperdix, Amphidromusatricallosusperakensis and Cyclophorussemisulcatus, were found around rock anvils in the nine plots. Finally, we discussed the potential and the limitations of using shell remains of preyed land snails for behavioural, ecological and evolutionary studies between land snails and their predators.

Spatio‐temporal patterns in the abundance of active terrestrial leeches in a Malaysian rainforest

AbstractTerrestrial leeches can be useful tools for wildlife assessment. However, limited information is available on their fundamental ecology, such as temporal activity patterns and habitat preferences in tropical rainforests. Therefore, this study aimed to reveal the temporal (diel and seasonal) and spatial patterns of active leech abundance and identify abiotic and biotic factors (abundance of potential hosts) involved in shaping the abundance patterns at Endau Rompin National Park (ERNP) in southern peninsular Malaysia. We conducted surveys on the relative abundance of active brown leeches (Haemadipsa sp.) at 99 sampling points repeatedly over 18 months, and installed camera traps to quantify the relative abundance of wildlife and humans at 24 of the sampling points. Although no consistent diel and seasonal patterns were observed in leech relative abundance, the abundance showed a strong positive correlation with air humidity at the sampling time. Similarly, the spatial pattern of leech relative abundance was positively correlated with air humidity and proximity to the nearest river at the sampling sites. The mean relative abundance of active leeches was 2–3 times higher on trails than off trails. However, there was no significant correlation between relative abundance of leeches and that of wildlife and humans on trails. Therefore, leech abundance was largely determined by air humidity rather than host abundance, suggesting the difficulty of its use as an indicator of wildlife abundance at fine spatial scales. Instead, utilizing the sensitivity of leeches to drier environments, terrestrial leeches could be useful as an indicator of intact tropical rainforests.Abstract in Malay is available with online material.

Isolation and Characterization of Werneria Chromene and Dihydroxyacidissimol from Burkillanthus malaccensis (Ridl.) Swingle

The secondary metabolites of endemic plants from the Rutaceae family, such as Burkillanthus malaccensis (Ridl.) Swingle from the rainforest of Malaysia, has not been studied. Burkillanthus malaccensis (Ridl.) Swingle may produce antibacterial and antibiotic-potentiating secondary metabolites. Hexane, chloroform, and methanol extracts of leaves, bark, wood, pericarps, and endocarps were tested against bacteria by broth microdilution assay and their antibiotic-potentiating activities. Chromatographic separations of hexane extracts of seeds were conducted to investigate effective phytochemicals and their antibacterial activities. Molecular docking studies of werneria chromene and dihydroxyacidissiminol against SARS-CoV-2 virus infection were conducted using AutoDock Vina. The methanol extract of bark inhibited the growth of Staphylococcus aureus, Escherichia coli, and Pseudomonas aeruginosa with the minimum inhibitory concentration of 250, 500, and 250 µg/mL, respectively. The chloroform extract of endocarps potentiated the activity of imipenem against imipenem-resistant Acinetobacter baumannii. The hexane extract of seeds increased the sensitivity of P. aeruginosa against ciprofloxacin and levofloxacin. The hexane extract of seeds and chloroform extract of endocarps were chromatographed, yielding werneria chromene and dihydroxyacidissiminol. Werneria chromene was bacteriostatic for P. aeruginosa and P. putida, with MIC/MBC values of 1000 > 1000 µg/mL. Dihydroxyacidissiminol showed the predicted binding energies of −8.1, −7.6, −7.0, and −7.5 kcal/mol with cathepsin L, nsp13 helicase, SARS-CoV-2 main protease, and SARS-CoV-2 spike protein receptor-binding domain S-RBD. Burkillanthus malaccensis (Ridl.) Swingle can be a potential source of natural products with antibiotic-potentiating activity and that are anti-SARS-CoV-2.

Study on the Effect of Different Crop Rotation Cycles on Forest Carbon Sequestration Capacity Based on Carbon Sequestration Model

Forests are extremely important ecological reservoirs and contribute significantly to the balance of global carbon cycling and carbon sequestration. In order to fully develop the carbon storage capacity of forests and consider the development of forest social efficiency, it is necessary to establish a reasonable model for the efficiency of forest carbon sequestration. The model should give effective management methods for different types of forests to replace the current widespread practice of over-logging or over-protection. We studied the carbon sequestration of forest vegetation and forest products separately and established a carbon sequestration model based on the effective area of forest. By simulating the effects of different rotation periods on forest carbon sequestration capacity, we conclude that a short rotation of about 10 years is most conducive to carbon sequestration in forests. On top of that, we extend the above evaluation model to the whole world, taking the Malaysian rainforest as an example to explore the best forest management model.

Aerobic Methanotrophy and Co-occurrence Networks of a Tropical Rainforest and Oil Palm Plantations in Malaysia

Oil palm (OP) plantations are gradually replacing tropical rainforest in Malaysia, one of the largest palm oil producers globally. Conversion of lands to OP plantations has been associated with compositional shifts of the microbial community, with consequences on the greenhouse gas (GHG) emissions. While the impact of the change in land use has recently been investigated for microorganisms involved in N2O emission, the response of the aerobic methanotrophs to OP agriculture remains to be determined. Here, we monitored the bacterial community composition, focusing on the aerobic methanotrophs, in OP agricultural soils since 2012, 2006, and 1993, as well as in a tropical rainforest, in 2019 and 2020. High-affinity methane uptake was confirmed, showing significantly lower rates in the OP plantations than in the tropical rainforest, but values increased with continuous OP agriculture. The bacterial, including the methanotrophic community composition, was modified with ongoing OP agriculture. The methanotrophic community composition was predominantly composed of unclassified methanotrophs, with the canonical (Methylocystis) and putative methanotrophs thought to catalyze high-affinity methane oxidation present at higher relative abundance in the oldest OP plantation. Results suggest that the methanotrophic community was relatively more stable within each site, exhibiting less temporal variations than the total bacterial community. Uncharacteristically, a 16S rRNA gene-based co-occurrence network analysis revealed a more complex and connected community in the OP agricultural soil, which may influence the resilience of the bacterial community to disturbances. Overall, we provide a first insight into the ecology and role of the aerobic methanotrophs as a methane sink in OP agricultural soils.

Testing the environmental prediction hypothesis for community‐wide mass flowering in South‐East Asia

AbstractGeneral flowering, in which hundreds of species synchronize their flowering at multi‐year intervals, is a puzzle to ecologists. It is hypothesized that species taking part in general flowering time their reproduction to meet favorable environmental conditions for seedling establishment. We tested this environmental prediction hypothesis using 14‐year weekly flower records of five Shorea species (Dipterocarpaceae) and daily meteorological data in a lowland rain forest in Malaysia. We first investigated causal inference between three potential flowering triggers (cooling, drought, and the synergistic signal of cooling and drought) and flowering. We then explored the causality between flowering triggers and moisture condition during seedling establishment. Our results demonstrated that the synergistic signal of cooling and drought causally influences flowering phenology with the highest predictability for the timing of flowering. Both drought and the synergistic signal of cooling and drought are causally linked to favorable wet conditions during seedling establishment, but the predictability of future rainfall by the synergistic signal was higher than the drought alone. These results support the environmental prediction hypothesis and raise the question as to whether climate change allows the prediction to hold for plant regeneration in the future.

Trade‐off between standing biomass and productivity in species‐rich tropical forest: Evidence, explanations and implications

Abstract Despite its broad implications for community structure and dynamics, we lack a clear understanding of how forest productivity is partitioned among tree species. As leaf mass per unit of standing biomass declines with tree size, species achieving larger stature should show lower relative productivity as compared to smaller stature species. However, many observations indicate large‐stature species grow faster than small‐stature species. In this study, we address this apparent paradox, and clarify interspecific trade‐offs between turnover rates and maximum size in terms of forest‐level productivity and biomass storage. We examined data from the 1990 and 2000 surveys of the Pasoh 50‐ha plot of Malaysian rain forest. In these data, individual stems ≥1 cm stem diameter (dbh) have been identified, marked, measured and mapped. We applied site‐specific equations to estimate tree biomass from dbh. We estimated species‐level productivity and loss rates that are less influenced by census interval‐related effects and biases. Among 390 abundant tree species, species with high stand‐level biomass were predominantly those large‐stature species where individuals could achieve large sizes. We found that relative (= per‐species‐biomass) productivity and loss rate, per‐capita recruitment and mortality of species were all negatively correlated to species biomass and maximum size, but not to species abundance. Large‐stature species grew faster than small‐stature species at the same tree sizes up to 36 cm dbh. However, the relative growth of large species at their maximum size markedly declined. As a result, tree‐level relative growth at maximum size and species‐level relative productivity decreased with species‐level biomass. Performing further analyses using smaller plots in four old‐growth forests in Indonesia and Japan, we observed a similar interspecific negative relationship between relative productivity and biomass. We expect this phenomenon is widespread across species‐rich forests. Synthesis. How productivity is partitioned among species determines and reflects forest ecosystem functioning and species coexistence. Many species with low biomass and small maximum stem sizes disproportionally contribute to forest primary productivity, rapid recovery and resilience. In contrast, long‐lived, high‐biomass species contribute disproportionally to ecosystem stability and carbon storage. This complementarity reflects differentiation by adult stature among species.

Shifts in foraging behaviour of heterospecific flocking birds in a lowland Malaysian rainforest

Mixed-species flocks (MSFs) serve important roles in bird communities, especially in tropical forests. Although structure of mixed-species bird flocks and its benefits has been intensively studied globally, the foraging plasticity of a species when joining MSFs has rarely been evaluated. The present study examines foraging strategies of the Rufous-crowned Babbler (Malacopteron magnum), Chestnut-winged Babbler (Cyanoderma erythropterum) and Black-naped Monarch (Hypothymis azurea) when participating in MSFs in the Krau Wildlife Reserve, central Peninsular Malaysia. These species exhibit active foraging shifts in utilisation of vertical strata, foraging substrate, attack manoeuvres and foliage density, when foraging in MSFs, compared to when foraging outside MSFs. While the Rufous-crowned Babbler and Chestnut-winged Babbler commonly used gleaning and stretching (to completely extend the legs or neck to reach the food items) manoeuvres when foraging outside MSFs, respectively, they adopted probing manoeuvre and frequently used higher strata upon joining MSFs. The Chestnut-winged Babbler tended to forage on the underside of leaves and the Black-naped Monarch frequently utilised branches when joining MSFs, while they exclusively used aerial leaf litter and live green leaves, respectively, when foraging with conspecifics. The monarch also adopted the hovering manoeuvre and frequently foraged within denser foliage cover when joining MSFs. This study demonstrated that flock members exhibits foraging plasticity either through an expansion or active shift in foraging niches when participating in MSFs, thus suggesting the occurrence of possible foraging improvement and/or reductions in predation risk.

Sensitivity of stomatal conductance to vapor pressure deficit and its dependence on leaf water relations and wood anatomy in nine canopy tree species in a Malaysian wet tropical rainforest

Canopy tree species with a large mean xylem vessel diameter has a high sensitivity of stomatal conductance to vapor pressure deficit in a wet tropical rainforest in Malaysia. We investigated the diurnal variation of stomatal conductance to water vapor (gs) and leaf water relations in nine tropical rainforest canopy tree species in Malaysia to investigate the sensitivity of stomatal conductance to VPD and its dependence on leaf water relations. We focused on the effect of wood anatomical properties on the stomatal sensitivity to VPD. Negative correlations were obtained between leaf-to-air VPD (VPDleaf) and gs for all species, in which interspecific variation was obtained for the sensitivity of gs to VPDleaf with the range of VPDleaf being 1.2–5.9 kPa. The species with large mean xylem vessel diameter had high sensitivity of gs to VPDleaf. Although significant variations were obtained among the species for leaf water relations, such as relative water content at the turgor loss point (RWCtlp) and water potential at the turgor loss point (Ψtlp), these water relations were not related to the stomatal sensitivity to VPDleaf. In the wet tropical forest in the present study, VPDleaf was the main regulator of gs in the nine tree species. The high sensitivity of gs to VPDleaf in the trees with a large vessel area may contribute to the maintenance of an adequate leaf water status, e.g., high levels of Ψleaf, throughout the day, across a period of varying air temperature.

How important is aerial leaf litter for insectivorous birds foraging in a Malaysian tropical forest?

Aerial leaf litter is a vital resource for insectivorous birds in tropical forests, particularly those that rely on dietary litter-dependent arthropods. The present study quantified and determined aerial-leaf litter selection patterns of specialist and regular dead-leaf users. In total, 486 observation sessions were conducted in a lowland tropical forest from February 2014 to September 2015. At least two ‘specialist’ species (over 75% of the observations) and seven ‘regular users’ species (25–74% of the observations) were found foraging for arthropods among aerial curled dead leaves within the aboveground vertical vegetation layers. These species belonged to four genera of the family Timaliidae and Pellorneidae: Cyanoderma, Stachyris, Pellorneum, and Malacopteron. The chestnut-winged babbler (Cyanoderma erythropterum) and the black-throated babbler (Stachyris nigricollis) were two species that heavily exploited the aerial leaf litter, accounting for 89% and 76% of the observations, respectively. The present study indicates that aerial leaf litter could serve as a vital foraging resource for most gleaning forest babblers in Malaysian rainforests. Moreover, niche separation among these dead-leaf foragers occurred due to their differing vertical strata preferences. The variations in body and bill sizes among the studied species suggest that they consume various arthropod sizes and taxonomic groups. A morphological analysis identified Hymenoptera, Coleoptera, and Arachnida as the dominant litter-dependent arthropods, and a molecular analysis revealed the presence of additional insect groups in the aerial leaf litter (e.g. Diptera and Lepidoptera). This study highlights the importance of maintaining undergrowth vegetation that can intercept aerial leaf litter to provide important foraging opportunities for forest bird species.

Stable isotope analysis reveals the importance of plant‐based diets for tropical ant‐mimicking spiders

AbstractAnt‐mimicking spiders are a well‐known example of Batesian mimicry. Earlier studies have proposed that plant‐based diets (e.g. extrafloral nectar) are an important food source for ant‐mimicking spiders. However, it is still unclear whether the plant‐based diets are a main food source or supplementary energy source to the spiders. To examine the feeding habits, we measured stable nitrogen and carbon isotope ratios (δ15N and δ13C) of ant‐mimicking spiders (six species of Myrmarachne; one species of Agorius, Salticidae; and two species of Corinnidae) collected from a tropical rain forest in Malaysia and a dry evergreen forest in Thailand. We also investigated the isotopic signatures of several ant species sampled from the two forests for comparison. In general, the ant‐mimicking spiders had relatively low δ15N values, which were comparable to those of the nectar‐feeding and omnivorous ants. The δ15N values of the ant‐mimicking spiders differed significantly among the species: some species (e.g. Myrmarachne sp. H and Myrmarachne sp. 2) showed δ15N values similar to those of the nectar‐feeding ants, whereas the δ15N values of others (e.g. Myrmarachne maxillosa and Myrmarachne malayana) were close to those of the omnivorous ants. The δ13C values of the ant‐mimicking spiders did not differ significantly among the species, but tended to be similar to those of the nectar‐ and honeydew‐feeding ants rather than the predatory ants. These results indicate that plant‐based diets are important for the nutrition of ant‐mimicking spiders and suggest that the importance would differ among the ant‐mimicking spider species.

Diet of tropical insectivorous birds in lowland Malaysian rainforest

ABSTRACTDespite the importance of diet in avian ecology, knowledge of bird diet in tropical regions, particularly South-East Asia, is limited. Assessing predator–prey relationships of how energy flows across ecosystems provides insight into niche segregation of sympatric species. We examined induced-regurgitation samples from 15 species of insectivorous birds – 12 babblers and three flycatcher-like species – from the Krau Wildlife Reserve, central Peninsular Malaysia. The main objective of this study was to compare and characterise the diet of similar trophically insectivorous birds so as to examine the occurrence of dietary overlap or segregation. The majority of identified prey items belong to the following arthropod taxa: Coleoptera (53%), Hymenoptera (19%), Blattodea (11%), and Araneae (11%). The diet of all bird species slightly overlapped (p = 0.070) but network analysis yielded a relatively low value (Ro = 0.53), indicating dietary divergence may have occurred among the studied bird species, possibly reflected by the variation in proportion of arthropod groups. A high proportion of Coleoptera and three other arthropod groups (i.e. Hymenoptera, Blattodea and Araneae) in the diet of studied birds could be related to their richness and abundance in aerial leaf-litter, the substrate preferred by most babblers. Dietary differences may further be explained by variations in bill shapes and sizes, likely corresponding to prey size. Unique foraging strategies (utilising different vertical strata, microhabitats, and attack manoeuvres) could also lead to dietary separation among sympatric species. Flycatcher-like species were expected to flycatch different prey items (families or lower taxa) versus the gleaning birds (most babblers). This study successfully discerned more details on the diets of insectivorous birds inhabiting Malaysian forests, providing a foundation for future studies on the ecology and biology of understorey birds.

Different cambial activities in response to climatic factors of three Malaysian rainforest Shorea species with different stem diameters

This study demonstrated that the cambial activities of three selected Shorea species with different stem diameters growing in a tropical rainforest in Malaysia responded differently to climatic factors. We investigated the cambial activities in Shorea leprosula, Shorea acuminata, and Shorea parvifolia trees with different stem diameters at breast height growing in a natural lowland dipterocarp rainforest in Malaysia. We collected and analyzed samples from the main trunks of selected trees in monthly intervals from March 2013 to April 2014. The cambium of the three Shorea species showed periods of active and less active growth in the humid forest. Selected trees with different stem diameters of the same and different species showed variation in rhythms of cambial activity (changes in the numbers of cambial and enlarging cell layers) at site with similar growing conditions. Monthly mean relative humidity and monthly mean vapour pressure deficit were important factors influencing the number of cambial cells of S. acuminata with larger stem diameter, and those of S. parvifolia with different stem diameters. Active cambium were detected in months with high relative humidity and low vapour pressure deficit in those trees. Total monthly precipitation had significant positive correlation with the cambial cells activities of S. parvifolia with different stem diameters, but no correlation with those of the other two species. The cambium of S. leprosula with smaller and larger stem diameters were found active throughout the year. We concluded that the three Shorea species examined with different stem diameters have different growth strategies and thus react differently to climatic factors.

Ancylostoma ceylanicum, novel etiological agent for traveler\u2019s diarrhea\u2014report of four Japanese patients who returned from Southeast Asia and Papua New Guinea

BackgroundCountries in the Southeast Asia region have a high prevalence of soil-transmitted helminth, such as roundworm, whipworm, and hookworms [Ancylostoma duodenale, Necator americanus, Ancylostoma ceylanicum]. Recent molecular-based surveys have revealed that A. ceylanicum, a zoonotic hookworm, is likely the second most prevalent hookworm species infecting humans in that part of the world, while others have noted that this infection is an emerging public health risk not only for indigenous people but also for visitors from other countries.Case presentationWe recently encountered four cases of A. ceylanicum infection in Japanese individuals who returned from Southeast Asia and Papua New Guinea. Case 1 was a 25-year-old male who stayed in a rainforest in Malaysia for 4 weeks, where he developed abdominal pain and diarrhea in the third week. Eleven adult worms (five males, six females) were expelled after treatment with pyrantel pamoate and identified as A. ceylanicum based on morphological characteristics and DNA sequences of the mitochondrial cytochrome c oxidase subunit 1 (cox1) gene. Case 2 was a 26-year-old male who spent 2 years as an overseas cooperation volunteer for agriculture in Papua New Guinea. He did not note any symptoms at that time, though eggs were detected in feces samples at a medical check-up examination after returning. Although collection of adult worms was unsuccessful, DNA analysis of the eggs for cox1 and the ribosomal internal transcribed spacer (ITS)-1 and ITS-2 genes demonstrated that they were A. ceylanicum. Case 3 was a 47-year-old male who spent 1 month in a rural village in Lao People’s Democratic Republic and began suffering from watery diarrhea from the third week. A total of nine adult worms (three males, six females) were collected by endoscopic procedures and following treatment with pyrantel pamoate. Morphological examination and molecular analyses of the cox1 gene showed that they were A. ceylanicum. Case 4 was a 27-year-old male who participated in group travel to India for 5 days. Three weeks after returning, he developed abdominal pain and diarrhea. Hookworm eggs were found in feces samples and developed into larvae in culture, which were identified as A. ceylanicum based on molecular analysis of the cox1 gene. Eosinophilia was observed in all of the cases prior to treatment.ConclusionsA. ceylanicum should be recognized as an important etiologic pathogen of hookworm diseases in travelers to countries in the Southeast Asia and West Pacific Ocean regions.