Research Article |
Corresponding author: Thilina Surasinghe ( tsurasinghe@bridgew.edu ) Academic editor: Wieslaw Bogdanowicz
© 2018 Gayan Edirisinghe, Thilina Surasinghe, Dinesh Gabadage, Madhava Botejue, Kalika Perera, Majintha Madawala, Devaka Weerakoon, Suranjan Karunarathna.
This is an open access article distributed under the terms of the Creative Commons Attribution License (CC BY 4.0), which permits unrestricted use, distribution, and reproduction in any medium, provided the original author and source are credited.
Citation:
Edirisinghe G, Surasinghe T, Gabadage D, Botejue M, Perera K, Madawala M, Weerakoon D, Karunarathna S (2018) Chiropteran diversity in the peripheral areas of the Maduru-Oya National Park in Sri Lanka: insights for conservation and management. ZooKeys 784: 139-162. https://doi.org/10.3897/zookeys.784.25562
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In Sri Lanka, there are 31 species of bats distributed from lowlands to mountains. To document bat diversity and their habitat associations, 58 roosting sites in Maduru-Oya National Park periphery were surveyed. Fifteen bat species were recorded occupying 16 different roosting sites in this area. Among all the species recorded, Rhinolophus rouxii was the most abundant species per roosting site whereas Kerivoula picta was the least abundant. A road-kill specimen similar to genus Phoniscus was found during the survey, a genus so far only documented in Southeast Asia and Australasia. Although our study area provided habitats for a diverse chiropteran community, the colony size per roost was remarkably low. Although our study area is supposedly a part of the park’s buffer zone, many anthropogenic activities are threatening the bat community: felling large trees, slash-and-burn agriculture, excessive use of agrochemicals, vengeful killing, and subsidized predation. We strongly recommend adoption of wildlife-friendly sustainable land management practices in the buffer zone such as forest gardening, agroforestry (alley cropping, mixed-cropping), and integrated farming. Bat conservation in this region should take a landscape-scale conservation approach which includes Maduru-Oya National Park and other surrounding protected areas into a regional conservation network. Extents of undisturbed wilderness are dramatically declining in Sri Lanka; thus, future conservation efforts must be retrofitted into anthropocentric multiuse landscapes and novel ecosystems like areas surrounding Maduru-Oya National Park.
behavior, conservation, habitat associations, roosting sites, species richness, threats
Sri Lanka is a small (65,610 km2), Indian Oceanic tropical island providing habitats for a rich mammalian diversity containing 126 species including 23 (~18%) endemic species (
Availability and diversity of roosting sites are paramount elements of life history of bats. A number of critical biological functions, such as reproduction, postnatal care, predator avoidance, and thermoregulation are provisioned by roosting sites (
There is a pressing need for local inventories of bat diversity to map species distributions throughout the island, which is critical for conservation assessments. Amongst the remaining Sri Lankan forest cover, the dry-mixed evergreen forests are largely secondary in origin, the most extensive and embedded in rural-agricultural landscapes (covering 21% of the island’s land area) (
Our specific objectives in this study were to (1) document species richness of bats in the periphery of Maduru-Oya National Park; (2) investigate their roosting site selection and identity local and landscape-scale land-cover types that influence presence of bats in potential roosting sites. Surveying habitats outside conservation lands is of conservation importance for several reasons. First, species distribution ranges may not be restricted by conventional protected area boundaries, thus bat occupancy can extend into the peripheral habitats of Maduru-Oya National Park. Thus, field surveys are necessary to confirm species occupancy outside the park. Secondly, we attempted to identify suitable bat habitats outside the park and thereby help re-delineation and management of a park buffer zone. Third, although bat habitats inside the park are protected from human disturbances and habitat loss, the same cannot be said for habitats of the park periphery. Therefore, documenting bat diversity and threats outside the park can help develop wildlife-friendly habitat management practices.
Peripheral landscapes of Maduru-Oya National Park (~58,850 ha; 7.3833–7.5833N and 81.033–81.3333E) comprise diverse habitat mosaics including woodlands, teak plantations, scrublands, grasslands, home gardens, croplands, lakes and reservoirs, streams, marshlands, and a variety of build-up environments (Figure
We conducted this survey for 2.5 years (May 2014 to December 2016) and surveyed 58 roosting sites found within a 2 km-wide peripheral area around Maduru-Oya National Park. Surveying roosting sites is highly effective and time-efficient for assessing bat diversity in a given region (
To test for differences in species compositions among different roosting sites, we ran a Multiple Response Permutation Procedures (MRPP) treating species composition of bats as response variable and different types of roosting sites as predictor variables. Here, we ran 500 permutations and used Bray-Curtis Index to calculate the distance matrix. To study patterns of roosting site selection by different species of bats, we constructed an ordination based on NMDS (non-metric multidimensional scaling). We calculated the distance measures from Bray Curtis index for different bat species. We extracted two axes with the lowest final stress that best ordinated the roosting sites in species space through 500 iterations with random starting configurations. To select dimensionality with the lowest stress, we ran a Monte Carlo test (60 runs from real data, and 60 runs from randomized data). We constructed an ordination plot with optimal axes to visualize patterns of roosting site selection. We used R–Studio (vegan and mgcv packages) for all statistical analyses (
To investigate the influence of land-use and land-cover types around potential roosting sites on presence of bats (using ArcGIS Pro 2.2) we extracted land-use and land-cover data from a reclassified global land cover data (
We recorded a total of 15 species of bats including 10 yinpterochiropteran and five yangochiropteran species representing six chiropteran families (Table
Roosting sites used by different bat species in the peripheral areas of Maduru-Oya National Park, Sri Lanka and relative abundance of each bat species at each type of roosting site. The number of sightings indicates the number of different days on which each bats species was present at a given roosting site. Superscripts denote national conservation status LC: least concerned, NT: near threatened, VU: vulnerable, EN: endangered. The global conservation status for all species was “least concerned”. Two more species (Cynopterus sphinx and Phoniscus cf. jagorii) were only recorded as dead specimens.
Family | Species | Trophic guild | Rooting site | Total no. of sightings | Avg. no. of individuals (std. dev.) | Used for day or night roosting? |
---|---|---|---|---|---|---|
Pteropodidae | Pteropus giganteus LC | Frugivore | Large tree | 11 | 22.54 (4.39) | Both |
Rousettus leschenaulti LC | Frugivore | Abandoned building | 34 | 15.60 (1.30) | Both | |
Hipposideridae | Hipposideros ater LC | Insectivore | Abandoned building | 10 | 5.56 (2.45) | Night |
Hipposideros lankadiva VU | Insectivore | Underneath bridge | 11 | 4.09 (2.34) | Night | |
Hipposideros speoris LC | Insectivore | Cave | 18 | 16.90 (0.32) | Both | |
Cave | 18 | 29.08 (4.25) | Both | |||
Cave | 18 | 49.56 (4.12) | Both | |||
Vespertilionidae | Kerivoula picta NT | Insectivore | Banana shrub | 21 | 2.13 (0.99) | Day |
Pipistrellus tenuis LC | Insectivore | Hollow tree | 10 | 6.78 (4.18) | Both | |
Megadermatidae | Megaderma lyra VU | Carnivore | Underneath bridge | 26 | 28.62 (2.09) | Night |
Underneath bridge | 26 | 22.4 (2.35) | Night | |||
Megaderma spasma VU | Carnivore | Abandoned building | 34 | 66.33 (3.89) | Both | |
Rhinolophidae | Rhinolophus beddomei VU | Insectivore | Cave | 09 | 5.11 (1.69) | Both |
Rhinolophus rouxii LC | Insectivore | Abandoned building | 34 | 285.00 (5.50) | Both | |
Emballonuridae | Taphozous longimanus EN | Insectivore | Cave | 09 | 40.14 (3.02) | Both |
Cave | 34 | 9.73 (5.36) | Both | |||
Taphozous melanopogon VU | Insectivore | Cave | 15 | 17.10 (6.51) | Both |
Bat species recorded in the periphery of Maduru-Oya National Park. a Hipposideros ater b Hipposideros lankadiva c Hipposideros speoris d Kerivoula picta e Megaderma lyra f Megaderma spasma g Pipistrellus tenuis h Pteropus giganteus i Rhinolophus beddomei j Rhinolophus rouxii k Rousettus leschenaulti l Taphozous longimanus m Taphozous melanopogon.
Habitats of bats in the peripheral areas of Maduru-Oya National Park. a a cave in Dananjaya Gala b rocky outcrops surrounded by forests c scrublands with temporary pools d small canal inside the forest e a cave nearby the Maduru-Oya reservoir f a historical cave in Damminna g a cave nearby Henanigala h under a large bridge.
We recorded three bats as road-kills, and identified two of them as Cynopterus sphinx and Rhinolophus rouxii (Figure
Morphological characteristics and morphometric features (mm) of the road-killed specimen (Phoniscus cf. jagorii) from Peripheral areas of Maduru-Oya National Park,, Phoniscus jagorii, Kerivoula hardwickii, and Kerivoula picta from Asia (
Character | Unidentified road-kill specimen (Phoniscus cf. jagorii) | Phoniscus jagorii | Kerivoula hardwickii | Kerivoula picta |
---|---|---|---|---|
Muzzle | The facial structure is damaged beyond characterization | Extremity of the mussel is projecting; covered with hair | Covered with hair; moderately small. Short, and pointed | Moderately small; long and rather pointed; densely covered with long hair which overhangs the mouth |
Ears | Large, few short hair at the base of ears; Tip of the ear rounded with a few short hairs (ear length: 14.03; ear width: 11.20) | Funnel–shaped large ears with rounded tips; two slight concavities– one just below the apex and another at the center of the posterior margin | Ears naked and relatively large, funnel shaped, tip rounded, inner margins regularly convex from base to tip, outer margins deeply concave immediately below the tip, the lower portions regularly convex. a prominent notch on tip of the posterior edge. | Moderately long; separate and distinctly funnel–shaped, bluntly pointed at tips; inner and outer margins terminating close together and giving the impression of almost complete cups; partially covered with short hair on the outer side |
Tragus |
Long, narrowing gradually to a point and a deep notch present on the posterior edge (tragus length: 8.44; tragus width: 2.11) |
Tragus rather broad at base and tapers to an acute point; white with deep notch on posterior edge | Tragus very long, narrow, and attenuated, outer straight–sided and sharply pointed | Very long, slender, grey in color; terminating in fine points |
Dorsal area of the body | Fur golden brown, black, and hair banded with four colors; dark grey–brown bases, then a buff band, then dark brown, then golden tips | Overall, golden brown and black; fur with four bands of color including a pale tip: dark brown or blackish–brown at the base, followed by buff, then brown, and finally golden or whitish–yellow tips; the paler tips are more pronounced on the ventral surface | Hair very soft and of moderate length; confined to the body and ceasing abruptly, both on the upper and the lower sides. General color of the upper parts rufescent brown although a few hairs could be pale–tipped; the hairs of the head, shoulders and mantle unicolored, those of the lower back and hinder parts generally, with the basal portions dark grey | Fur rather long, dense, and woolly; Extending slightly onto the membranes near the body; dorsal fur orange or tawny–red |
Ventral area of the body | Fur paler grey to dark brown with golden tips | Under parts paler with slightly greyer tips | Lower parts, light rufescent–fawn, with the basal portions of the hairs dark brownish grey and paler grey hair tips; membranes and ears unicolored, semi–transparent blackish brown | Compared to dorsum; ventral hair is paler and yellowish |
Ante–brachial membrane | Naked | Naked | Semi–transparent, thin in texture | Sparingly but visibly covered with many minute hairs on both surfaces; bright orange to scarlet in color. |
Wing membrane | Naked and well developed. Attached to the ankle | Attached to the ankle | Arise from the base of the outer toes. Brown–colored but nearly transparent; upper surface almost naked, expect for a thin spread of small hair. | Moderately long and broad with the membrane attached to the base of the toes; orange to bright scarlet along the length of the forearms and fingers the rest is black |
Interfemoral membrane | Ventral side naked, dorsal side is partly covered with hair; membrane is well developed and semi–transparent | Hair very short and almost invisible; the margins are mostly naked; sometimes with sparse sprinkle of hair | Naked, well developed; thin in texture and semi– transparent. Long scattered hair present on femur and tibia, feet are almost naked; no prominent fringe on the posterior boarder but scattering hair may be present | Sparingly but visibly covered with many minute hairs on both surfaces; bright orange to scarlet in color |
Tail | Tip of the tail projects slightly (tail length: 40.54) | Tip of the tail projects slightly | Tail considerably shorter than the head and body | Long tail (as long as the head and the body) entirely contained within the interfemoral membrane |
Radio–metacarpal pouch | Absent | Absent | Absent | Absent |
Forearms and hand | The metacarpals and digits covered with short, golden hair (Forearm length: 37.64; thumb + claw length: 7.33; 2nd–5th metacarpal lengths: 37.37, 36.80, 34.32, 35.04) | Short shiny yellow hairs along forearm and fingers | Hair absent on forearms or hands | No hair on forearms; Hair on metacarpals and digits are sparse and scattered. Bright orange color on all fingers and metacarpals |
Feet | Few short golden hairs present (tibial length: 18.70; foot length: 09.58) | Short hair present on the hind feet | Feet small, equipped with relatively long, sharp claws, with a few short hairs on the toes | Feet small, densely–covered with short reddish–brown hairs and equipped with sharp small claws |
Calcar | Long; covered with a dense fringe of short golden hairs (calcar length: 11.22) | Calcar relatively long; No hair on the calcar | Calcar long, extending approximately two–thirds of the distance from the ankle to the tail | Well developed with no lobes; covered with a dense fringe of short reddish hairs |
Road killed specimen of Phoniscus cf. jagorii with key characters a wingspan with the dorsal body color b Interfemoral membrane is well developed and semi–transparent (parts of the interfemoral membrane was damaged) c Long, tapering, notched tragus d forearm and digits covered with short, golden hair e ventral aspect of the wing.
We noted four different types of roosting sites frequently occupied by bats in our study area. These included caves of different sizes, different locations of large mature trees and banana trees, abandoned buildings, and underneath of bridges (Table
The MRPP analyses showed significant differences in species composition of bats across different roosting sites (Chance corrected within group agreement = 0.14, expected δ = 0.73, observed δ = 0.62, p = 0.001). The NMDS ordination reached a stable solution (mean stress = 0.08) after 500 iterations and produced two axes. The Monte Carlo randomization also suggested that the two axis solution was optimal (stress in randomized data = 0.26, p < 0.05). The stress level we reached (closer to 0.05 and less than 0.1) in our stable solution with two dimensions suggests a good fit of our dissimilarity object. The ordination plots (axes 1 and 2) indicated substantial segregation of the different species based on the roosting sites selected (Figure
NMDS Ordination of Bat association with different roosting sites in Maduru-Oya National Park periphery. The ellipses represent 95% confident intervals around the centroids. Cynopterus sphinx and Phoniscus cf. jagorii, which were only recorded as dead specimens, were not included in the ordination.
The GAM we constructed indicated that both the percent cover of crop-mixed natural vegetation and percent forest cover at 500 m radius are of significantly important predictors of bat presence in potential roosting sites (Table
Local (500 m radius around the roosting site) and landscape-scale (5 km radius around the roosting site) predictors of bat presence at potential roosting sites derived from a binomial generalized additive model (no large wetlands or aquatic land cover types were found within a 500 m radius).
Land-use variable | Coefficient estimate | z | p | |||
---|---|---|---|---|---|---|
500 m | 5 km | 500 m | 5 km | 500 m | 5 km | |
Agricultural lands | 0.52 | -3.10 | 0.97 | -1.30 | 0.33 | 0.19 |
Scrublands | -0.32 | 0.47 | -0.96 | 0.49 | 0.34 | 0.62 |
Crop-mixed scrublands & woodlands | 0.60 | -0.84 | 2.10 | -0.90 | 0.04* | 0.37 |
Other vegetation mosaics | 0.75 | -0.71 | 1.54 | -0.87 | 0.12 | 0.39 |
Forests (woody vegetation) | 1.38 | -0.67 | 2.81 | -0.76 | 0.005 ** | 0.44 |
Wetlands and other open water bodies | n/a | 0.13 | n/a | 0.22 | n/a | 0.82 |
The bat species richness in the peripheral areas of Maduru-Oya National Park is remarkable as this bat community represents six of the seven Sri Lankan chiropteran families and ~50% of the island’s total bat species (
Our discovery of Phoniscus cf. jagorii in our survey is noteworthy. The genus Phoniscus is currently known from four species, three of which are from Southeast Asia, New Guinea, and Eastern coast of Australia (
Nearly all the active roosting sites we documented were located within or in proximity to dense forests. These observations suggested that most bats of Maduru-Oya area are forest dependent. Our GAM for species presence also indicated forest dependency of these bats in terms of roost selection. Forest habitats provide a diverse array of high-caloric and nutrient-rich food resources for foraging bats. Our inferences about forest-dependency of bats are consistent with surveys conducted elsewhere in Sri Lanka and other humid tropical regions (
Although we visited >50 potential roosting sites, only a quarter of those had bats at least once during our surveys. Also, a number of caves we visited had indirect evidence (guano) for bat presence. These observations may indicate lower site fidelity of bats at our study area where bats may shift between different roosting sites. Such high roost lability can be attributed to lower cost in commuting to foraging grounds, high familiarity with multiple roosts that vary in microclimatic conditions, greater availability of high-quality roosts; nest lability also ensures increased cross breeding potential, reduced predation risk, and lowered parasitic loads (
Access to suitable roosting sites is a critical element for bats’ life-history functions. Human-occupied landscapes usually contains forest preserves, mature woody vegetation, and buildings, therefore, may provide shelters for bat roosting compared to agricultural landscapes under intensive commercial farming which may lack a diverse array of roosting sites (
Although our survey covered potential roosts in agricultural habitats, none of those were occupied by bats, except for Kerivoula picta we documented from a banana plantation. Reduced overall bat activities (foraging and roosting) have been reported from agricultural landscapes in tropical Southeast Asia as well as the northern template of American Midwest (
Caves appeared to be the preferred roosting sites for most bats in our study area; similar habitat preferences have also been reported elsewhere in Sri Lanka (
Members of the family Pteropodidae (Old World Fruit bats) mostly roost on large, mature trees and deserted buildings as confirmed by our study (
Presence of bats in potential roosting sites was only significantly influenced by forest cover and crop-mixed natural vegetation cover (woodland and scrubland mosaics with multiple types of crops) whereas the former was the most impactful predictor. Both of those predictors were only significant at local (500 m radius around the roosting site) scale not at the landscape-scale. Importance of mixed vegetation mosaics, particularly those embedded with polyculture practices (comparable to analog forests and permaculture systems) as a local-scale land-cover predictor warrant further investigation. This may indicate use of such vegetation mosaics by open-space and edge foragers. In contrast to our findings, a multitude of other studies have underscored the importance of landscape-scale features for bat occupancy in potential roosting sites (
Mahaweli Development scheme and subsequent expansion of human settlements, and agricultural intensification have resulted in tremendous habitat transformations in the landscape structure in Maduru-Oya area (
We recommend a landscape-scale approach for bat conservation of Maduru-Oya area, which entails conservation of roosting sites and associated habitats, particularly forest patches and aquatic habitats both within the national park and peripheral wilderness (
Different species of bats we documented differed markedly in their natural histories. For instance, Rhinolophus rouxii forages in the foliage of dense forests (
Our study underscored the importance of conservation outside protected areas. Previous studies have also highlighted the importance of “trees outside the forests” for biodiversity conservation (
Chiropterans are salient for multiple ecological functions, regulating invertebrate populations, serving as a prey-base, seed dispersal, and pollination, thus conservation of bats is imperative for healthy ecosystems (
We express our gratitude to local communities of Maduru-Oya National Park, Wasantha Kumara, Lakshman Dayarathne, Sudharman Dayarathne, Mayura Dayarathne, Hobary Silva, late Wewatte Jaye, Nadeesh Gamage, Niranjan Karunarathna, and Mahesh De Silva for their support during the field work; Warden and staff at the Maduru-Oya National Park and Department of Wildlife Conservation, Forest Department, Sri Lanka Army, and local police officers for various assistance; Pipat Soisook, Chelmala Srinivasulu, Tigga Kingston, and Maria Armour for providing valuable feedback. This study was partially supported by Biodiversity Secretariat of Sri Lanka.
Compliance with Ethical Standards: The authors declare that they have no potential conflicts of interest. Research involving animals are approved by Clemson University IACUC Protocol. No humans subjected were involved in this research.