Small Mammals

Rodentia (Muridae, Sciuridae), Scandentia (Ptilocercidae, Tupaiidae), Eulipotyphla (Erinaceidae, Soricidae)

Title: Effects of habitat fragmentation on non-volant small mammal communities on Borneo (Sabah, Malaysia).

PhD candidate: Jennifer Brunke

Supervisors: Apl. Prof. Dr. Ute Radespiel, Dr. Benoit Goossens

Institution: University of Veterinary Medicine Hannover

Duration: ongoing since 2011

Summary

The increasing fragmentation of tropical rain forests, due to anthropogenic landscape changes, poses increasing problems for their biodiversity. Changes of natural habitats affect individuals of different species in a variety of ways. In contrast to large mammals, the knowledge about how small mammals can cope with habitat fragmentation is in its infancy. However, small mammals are not less important for the maintenance of ecological balance within habitats, and are not necessarily less vulnerable to anthropogenic changes.

More than 60 non-volant small mammal species are known to occur on Borneo. More than half of these species are endemic to Borneo. Taxonomically, communities of Bornean non-volant small mammals contain various species of Eulipotyphla (i.e. Erinaceidae and Soricidae), Scandentia (i.e. Ptilocercidae and Tupaiidae), and Rodentia (i.e. Sciuridae and Muridae) that differ largely in life styles and ecology. As a result of large-scale logging activities and habitat conversion 20% of Bornean small mammals are already listed as endangered, vulnerable, or near threatened by the IUCN. For the development of effective conservation measures and to determine the susceptibility of small mammal species, it is essential to understand the consequences of anthropogenic disturbances on population numbers and viability.

Objectives:

This project aims to assess the susceptibility of non-volant small mammal species to increasing habitat fragmentation and accompanying changes in habitat conditions in the remaining lowland rainforest along the Kinabatangan River. Along the river numerous woodlands have been cleared or converted to anthropogenic landscapes. Nowadays, oil palm plantations dominate the landscape and forests are restricted to isolated patches. These forest fragments provide an ideal setting for the assessment of fragmentation effects to the native biota, since they vary in size, degree of habitat disturbance and connectivity.

With this project we want to acquire knowledge about the factors that determine their vulnerability towards habitat fragmentation and habitat disturbance. To achieve this we will monitor small mammals in a larger number of forest patches along the Kinabatangan River and assess the influence of various environmental factors (e.g. patch size, degree of isolation, barriers of various quality and size, habitat structure, edge effects) and species-specific traits (e.g. habitat specialization, activity pattern, degree of terrestriality, reproductive rate) on their population viability.

Methods:

For the assessment of potential correlations between fragment quality and the diversity and abundance of small non-volant mammals within these patches structural habitat variations across forests will be identified and diversity and abundance of small mammal species will be described for each study site. These species richness measures of small non-volant mammal communities will be directly related to various collected habitat characteristics to assess existing habitat preferences and specialization. Using state-of-the-art genetic modelling approaches, we furthermore aim to estimate impacts of habitat fragmentation and disturbance on the diversity and gene flow of small mammal populations. Genetic structures across fragments and the effects of potential barriers (small/large rivers, oil palm plantation) will be tested, contrasted to isolation by distance effects. Different predictions on the impact of habitat fragmentation on genetic diversity, gene flow and structure will be investigated by means of mitochondrial and nuclear marker.

Expected outcomes:

By acquiring knowledge about species species-specific susceptibilities and viabilities toward habitat disturbance, the actual endangerment of Bornean small mammals can be evaluated. Furthermore, this project will provide valuable results that will be of prime importance for the management of existing and newly established conservation areas. The results can be used to formulate a comprehensive management plan of the Lower Kinabatangan Wildlife Sanctuary that tackle the problem of forest fragmentation and forest degradation and aims to designate forest corridors in this area.

Collaborators: Sabah Wildlife Department, Michael W. Bruford, Cardiff University