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- ITSES - |
Eurasian Insectivores and Tree Shrews:
Status Survey and Conservation Action Plan
Published 1995
Foreword - Return to Top of Page | Table of contents
One of the curiosities of eastern Nepal is a little-known insectivore known locally as "pani musa", or "water rat". Knowing that its occurrence in the mountains to the east of Mt. Everest, on the border with Tibet, was still only suspected, I spent several weeks in 1973 seeking to confirm its occurrence there. With teams of local Sherpas, we trudged through many mountain torrents, turning over rocks, searching for evidence, and setting live traps. Our efforts were finally rewarded by capturing one individual of this elegant little water shrew, with amazingly silky fur, webbed feet with fringes, and a paddle-like tail. The local people were well aware of the existence of this animal, though they paid little attention to it because it was so innocuous and seemed to have so little to do with their affairs.
In this sense, the Nepalese were no different than most other people in the world: insectivores are basically unknown, unnoticed, and unloved. Yet as this Action Plan shows, these inconspicuous members of virtually all ecosystems throughout Eurasia are an important part of the ecological fabric of the region.
How, then, can greater public interest be aroused? Or at least, how can the conservation needs of these species be better incorporated in conservation plans? A useful first step might be to identify which on-going or planned projects are taking place in important habitats of key insectivores and tree shrews. For example, the Kerinci region of West Sumatra is the site of a major project receiving funding by the Global Environment Facility (GEF). This region supports populations of the critically endangered Sumatran water shrew, the moonrat, the lesser gymnure, and no less than four species of tree shrew as well. Thus insectivores and tree shrews can help to enhance the importance of the Kerinci project for global biodiversity, thereby contributing to an important international effort.
Those interested in insectivores and tree shrews might then ask how projects already planned or under way might be modified to better address the needs of insectivores and tree shrews. Many of these projects include public information components, so those interested in these animals should devise approaches that will enable information about insectivores and tree shrews to contribute to such public information programmes. Several of these projects have research components, and these could be modified to incorporate appropriate research into tree shrews and insectivores.
Other important research questions for which answers might be sought could include:
- What role do insectivores play in maintaining the diversity of insect
faunas?
- What role do moles and fossorial shrews play in the cycling of nutrients
and water in forested ecosystems?
- How do tree shrews affect forest regeneration? Do they play any role
in seed dispersal? Control insects which prey on seedlings?
- Given that some populations of widespread species of shrews are becoming
isolated, can these populations be used for the study of speciation?
- What are the habitat requirements of key species, and what are the
management implications of these requirements? If some species of tree
shrews, for example, prefer early successional habitats, how should protected
areas be managed to maintain such habitats?
The kinds of research implied by such questions will lead to an expanded appreciation of tree shrews and insectivores, demonstrating that they have an ecological importance far greater than is generally appreciated. I hope very much that this Action Plan leads quickly to new avenues of research that extend beyond basic taxonomy and distribution, and begin to investigate why insectivores and tree shrews are deserving of a significant investment by people in their conservation.
Executive Summary - Return to Top of Page | Table of contents
This Action Plan addresses the conservation needs of two unrelated groups of small mammals: the Insectivora (non-volant mammalian insectivores) and Scandentia (tree shrews) of Eurasia. It provides a review of what is currently known about the taxonomy, distribution, conservation status and requirements of almost 200 species. In assessing and evaluating these criteria, this Action Plan constitutes a first attempt to identify and prioritise species in terms of the degree of threat and need for conservation action. In addition, and through a series of specific recommendations, it seeks to stimulate further activities in order to promote a greater awareness of the extent of the threats facing certain species and the need for conservation action.
Insectivores are among the most numerous and widespread small mammals of the Eurasian region. For the purpose of this review, 180 species have been considered. The tree shrews form a separate, cohesive group of 19 species and are confined entirely to South and south-east Asia. Although unrelated, insectivores and tree shrews have a number of physical and behavioural features in common: both groups exhibit a number of primitive features, such as simplified dentition; all are predominantly insect-eating animals; and forests (both tropical and temperate) are one of the most important habitats of both groups. Insectivores, however, are not only confined to forests: many are fossorial, aquatic or terrestrial, living under a wide range of climatic and altitudinal conditions. They therefore face a much broader range of potential threats than tree shrews.
In spite of their ecological and evolutionary importance, insectivores and tree shrews remain some of the least well-known mammals. The majority of species are relatively unimportant to humans in economic terms; a limited number have been trapped for their fur or as a source of food, and only a few are considered pests. As most species are nocturnal, or secretive in other ways, many people are often unaware of the existence of these species. Tree shrews, perhaps the most obvious and visible of the two groups, are an exception but until recently have been almost totally ignored by field ecologists. In terms of their biomass, however, all of these species fill a major ecological role as predatory small mammals. Many also fill a range of unique niches. Yet, because these are not high profile animals, they are often overlooked in surveys when conservation or development plans are being drawn up for a region. For these reasons it is essential that the ecological requirements of these species be determined and a greater awareness generated of their conservation needs.
The most important single threat to insectivores and tree shrews is habitat destruction. This takes many forms: in western Europe, for example, removal of hedgerows, expanding road networks, intensive cultivation with widespread use of fertilizers and pesticides, and drainage of wetlands is having a noticeable impact on the numbers and distribution of many species. Water pollution, combined with the construction of hydro-electric dams and canals, threatens aquatic species throughout the region. Wetland drainage is also a major problem in south-east Asia. Of greater consequence in this region, however, is the level of human encroachment into tropical forests; slash-and-burn cultivation and logging are destroying vast areas of prime habitat for many species. Although little evidence is available on the effects such clearance may have on insectivore and tree shrew populations, it is highly likely that the combined effect of these processes could, in the long-term, lead to serious habitat fragmentation and isolation of small, vulnerable populations. Species at particular risk are those with already restricted distributions as well as the many monospecific genera covered in this Action Plan.
Perhaps the greatest problem in formulating conservation recommendations for insectivores and tree shrews is the current lack of data on the ecology, distribution and conservation status of the vast majority of species. The secretive nature of a great many of these animals has meant that vital information such as the extent of a species' range or population size is often lacking, or that few details exist on their natural history, ecology or conservation status. Using the most recent guidelines prepared by IUCN on how to identify threatened species, this report demonstrates that many species are endangered or threatened: 13 species have even been classified as "Critically Endangered" (Table 1). The current lack of reliable field data almost certainly prevents the identification of other potentially threatened species. It also impedes the formulation of definite conservation actions. On occasion, this problem is further compounded by uncertainties regarding taxonomic status. Such limitations hinder action that might help identify impending threats to a given species and its habitat, and enable remedial action to be taken. For these reasons, threats to insectivores and tree shrews often go unnoticed until it is too late to act. Future emphasis should be given to conducting additional field surveys to prepare and implement specific conservation programmes of these species and their habitats.
Despite the limitations imposed by the current lack of information on many species, this Action Plan still has an important role to fulfil in highlighting the need for action for at least those species which have been identified as threatened. In reviewing this information, a number of priority actions have been identified for the conservation of insectivores and tree shrews, specifically to draw attention to the need for, and to promote:
- further action - particularly field surveys of poorlyknown species
- in order to assess distribution and conservation status and to identify
remedial action where appropriate;
- contact with field ecologists, taxonomists and geneticists, who are
asked to communicate any observations on insectivores and tree shrews in
Eurasia to help improve the scant information on those rarer, poorly known
species;
- cooperation with ongoing conservation efforts throughout Eurasia so
that, when appropriate, recommended and approved actions by ITSES - the
Insectivore, Tree Shrew and Elephant Shrew Specialist Group-can be incorporated
within existing or intended projects;
- the interest of universities, associated institutes and expeditions,
which are often of considerable importance by stimulating interest and
research related to conservation; and
- public awareness of the importance of habitat conservation; what benefits
a shrew, for example, will almost certainly be of great benefit to a much
wider range of wildlife. Often, this may also result in positive fringe
benefits for local human communities.
In the first instance, the target audience of this Action Plan is ecologists and researchers. Only when more specific details are known about the conservation status and threats to endangered species can action be pursued at other levels. In publishing this Action Plan an appeal is therefore made to scientists, members of other SSC groups and the wider public to gather and promote more information on Eurasian insectivores and tree shrews. It is anticipated that this will help stimulate further action and enable ITSES to prepare a more specific list of priority conservation projects for Eurasian Insectivora and Scandentia, which it can use as a definite statement when applying to relevant authorities for further action.
Use of this Action Plan can also serve objectives additional to those listed above, for example, assisting in regional assessments of biological diversity and habitats. These could vary in scope and nature, depending on the specific issues and/or projects being dealt with. It is ITSES' hope that this Action Plan will reach a wide audience and will help stimulate and direct future field projects on behalf of the conservation of insectivores and tree shrews in the Eurasian region.