Lambir animal mortalities project
From BioDivBorneo2010
Animal mortalities on the highway in Lambir Hills National Park
Thasun Amarasinghe and Juwinikh Jupain
Contents |
Abstract
The increase in road networks throughout the world has brought about for a concern for the effects of vehicular traffic on flora and fauna. Development in any area generally leads to extensive road networks and subsequent traffic. The effects of such landscape changes can be dramatic on fragile habitats, such as the rainforests of the Borneo. This present study provides evidence of the impacts of vehicular traffic on the rainforest fauna of Lambir, Borneo. A total of 28 individuals of roadkilled animals (28 individuals/km), belonging to 9 orders were recorded. Chiropteran bats represented one third (36%, N=10) of the total number of individuals recorded. The Shannon Wiener Index for the diversity in rainy day: 0.66 and non rainy day: 0.23.
Introduction
The increase in road networks throughout the world has brought about for a concern for the effects of vehicular traffic on flora and fauna. This concern is evidenced by the increasing amount of literature dealing with the ecological effects of roads and traffic (Forman & Alexandra, 1998; Spellerberg, 1998). Roads are known to cause forest fragmentation (Forman & Alexandra, 1998; Goosem, 1997; Reed et al., 1996). Highways in turn pose a threat to animals, not only by way of habitat fragmentation, but resulting in direct mortality by being run over by motor vehicles, and also due to thermal stress while trying to cross a heated surface (Bambaradeniya et al, 2001; Vijayakumar et al, 2001) and affect the density of amphibians (Fahrig et al., 1995), cause barriers to dispersal of arthropods (Mader et al., 1990), reduce average heterozygosity and genetic polymorphism among frogs (Reh & Seitz, 1990) and affect the physical environment (Spellerberg, 1998).
Development in any area generally leads to extensive road networks and subsequent traffic. The effects of such landscape changes can be dramatic on fragile habitats, such as the rainforests of the Borneo. Sarawak of Borneo has experienced large-scale changes. The impact of roads on the flora and fauna of this region is poorly documented.
This present study provides evidence of the impacts of vehicular traffic on the rainforest fauna of Lambir, Borneo. We explore the probable causes for such mortality and examine some secondary effects of roads and traffic on the rainforest fauna.
Study area The study was conducted in and around the Lambir Hills National Park (LHNP), Sarawak, Borneo. The township is surrounded by forests which are part of the LHNP. The road segment sampled forms part of the highway connecting Miri and Bitulu across the LHNP. The roadside vegetation is regularly cleared and maintained by the Public Works Department. The town is one of the fast expanding commercial areas for palm oil. These factors have led to an increase in the volume of traffic by tourist and commercial vehicles over the years.
Methods
Roadkills were sampled in five different road segments, each 100 m. The natural vegetation of the area has been classified as wet-evergreen forests. These road segments traversed through the fragments of rainforest and along the edge of the fragment. We walked these road segments during early hours in the morning looking for road kills. On sighting a roadkill, the roadside habitat, state of the roadkill, and the location of the roadkill on the road segment were recorded. All road-killed individuals were examined and photographed but not collected. Highly damaged specimens were removed from the road to avoid multiple counts of the same kill. Sampling was repeated two days and the order of sampling the road segments was randomized.
Most road-killed animals were damaged, thus sometimes impeding identification to the species level. Therefore, specimens were identified to Order level; a few specimens were identified to family. Data from the four road segments were pooled for the purpose of analysis. We did not attempt to compare road segments, because of their variability in slope, distance sampled and vegetation categories along the road. Roadside vegetation was divided into four categories, viz. forest, forest-banana, Open ferns and forest- degraded based on the combination that existed on either side of the road. In order to make comparisons of roadkills across these vegetation categories, the frequency of roadkills was expressed as the number of individuals per km. We recorded the occurrence of rainfall during the study period. The Shannon Wiener Index was used to determine the diversity. H = -∑s (Pi) (log Pi): H = Diversity of species; S = Number of species; Pi = Proportional frequency of the ith species.
Results
A total of 28 individuals of roadkilled animals (28 individuals/km), belonging to 9 orders were recorded. Chiropteran bats represented one third (36%, N=10) of the total number of individuals recorded, followed by Lepidoptera (21%, N = 6), Odonata (18%, N = 5), Hymanoptera (4%, N=1), Serpentes (4%, N=1), Gastropoda (4%, N=1), Anura (7%, N=2) and Rodentia (7%, N=2). For invertebrates, more than 45% (N = 6) of the road kills are Lepidopterans. The Mollusks was represented by a single species. The number of individuals collected as roadkills during rainy and non-rainy days was different for all the animals except insects. The Shannon Wiener Index for the diversity in rainy day: 0.66 and non rainy day: 0.23. Therefore on rainy days the diversity of road kills higher than the rainy days.
Discussion
This study was conducted for only two days; therefore the data is not enough to run non-parametric tests such as Mann-Whitney U-tests or T tests. Therefore cannot conclude whether there is a significant different of road kills during rainy days and non rainy days. Also this study should be continued for long time for long road segments to identify the effect of rain and vegetation type.
Acknowledgements
We would like to acknowledge Prof. Cam Webb for providing valuable guidance and help during the field work. Finally we would like to thank Frank Reindt, Dave Lohman and Kinari Webb for valuable comments and help.
Literature Cited
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