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INSECTIVORE, TREE SHREW & ELEPHANT SHREW SPECIALIST GROUP


Eurasian Insectivores and Tree Shrews:
Status Survey and Conservation Action Plan
Published 1995


Introduction | Insectivora | Scandentia | Geographical Coverage | ITSES | Threats | Action Plan



Chapter 1

Introduction


With 423 species recognised worldwide (Hutterer, 1993), insectivores (Order Insectivora) are the third largest order of mammals after rodents and bats. They are largely confined to the northern temperate zones of North America, Europe, the former Soviet Union, Africa, and southern Asia. The tree shrews (Order Scandentia) constitute a much smaller group of just 19 species, all of which are restricted to South and south-east Asia; it is the best single group for defining the Indo-Malayan Realm. Another group of small, terrestrial mammals which share many of the primitive features of Insectivora and Scandentia is the Order Macroscelidea, the elephant shrews of Africa. Fifteen species are recognised in this order (Wilson and Reeder, 1993).

Apart from their small size, members of these three groups are characterised by their general tendency to feed on invertebrates, although many species also take a range of small amphibians, seeds and fruit. Most are opportunistic hunters. To assist with feeding, many species have developed additional specialisations, such as the paralysing bite of the mole or water shrew, as well as prey-caching behaviour among many terrestrial and fossorial species.

Most insectivores are highly secretive species and often nocturnal. Their habitats range from and and semiand conditions to montane forests, and from semi-aquatic tendencies to living under desert and Arctic conditions. The majority are terrestrial, but some are fossorial, semifossorial, aquatic or even arboreal in habit. Combined with a small body size, their secretive nature has resulted in the majority of these species being neglected or overlooked in many field surveys. As a result, little is known about the distribution, behaviour or ecology of the majority of these animals.

This Action Plan has been prepared as a first step to addressing this oversight. Prepared by the IUCN/SSC Insectivore, Tree Shrew and Elephant Shrew Specialist Group (ITSES), it examines the current status and conservation needs of the Insectivora and Scandentia of Eurasia. Similar coverage has already been compiled for the Insectivora and Macroscelidea of Africa (Nicoll and Rathbun, 1990).


1.1 The Insectivora of Eurasia - Return to Top of Page | Table of contents

The Order Insectivora is ancient. Fossil evidence now indicates that the most primitive placental mammals were insectivores. Today's species are considered representative of the ancestral stock from which modern mammals are derived. Their descendants have retained a number of primitive features, including a non-specialised dental pattern, a simple brain, a reliance on their sense of smell (as opposed to vision), unspecialised limbs and a generalised quadrupedal mode of locomotion.

The Insectivora comprise a wide variety of largely insectivorous mammals which have often been grouped together because of common morphological traits rather than a clear, recent common ancestry. The taxonomic classification of insectivores has been reviewed in detail by Cabrera (1925), van Valen (1967), Gureev (1979), Butler (1988), Yates (1984) and Hutterer (1993). As a result of these, and other, investigations the Family Tupaiidae (tree shrews), which was once included in the Order Insectivora, has now been assigned a separate order - Scandentia. Likewise, elephant shrews (Family Macroscelididae) are now placed in a distinct order Macroscelidea.

As a result of these reviews, the Order Insectivora is now seen to contain six extant families, of which just three are represented in the Eurasian region: Erinaceidae (hedgehogs), Soricidae (shrews) and Talpidae (moles and desmans) (see Table 1.1).

Table 1. 1. Taxonomic summary of the
Eurasian Insectivora (Hutterer, 1993)
Genus

Number of species

Family Erinaceidae (hedgehogs)
Atelerix
Echinosorex
Erinaceus
Hemiechinus
Hylomys
Mesechinus
Podogymnura

Subtotal

Family Soricidae (shrews)

Anourosorex
Blarinella
Chimarrogale
Crocidura
Diplomesodon
Feroculus
Nectogale
Neomys
Solisorex
Sorex
Soriculus
Suncus

Subtotal

Family Talpidae (moles)

Desmana
Euroscaptor
Galemys
Mogera
Nesocaptor
Parascaptor
Scapanulus
Scaptochirus
Scaptonyx
Talpa
Uropsilus
Urotrichus

Subtotal

Total

1
1
3
6
4
2
2

19



1
2
6
55
1
1
1
3
1
34
10
11

126



1
6
1
7
1
1
1
1
1
9
4
2

35

180




1.2 The Scandentia of South and South-east Asia - Return to Top of Page | Table of contents

Tree shrews (Order Scandentia) are small mammals found in the tropical rainforests of southern and southeastern Asia. Superficially tree shrews resemble small tree squirrels - the genus name Tupaia is derived from the Malay 'Tupai', meaning 'squirrel-like animal'- but it is now recognised that the two groups differ widely in anatomy and behaviour. Most species of tree shrew are semi-terrestrial, but all are agile climbers; tree squirrels are almost exclusively arboreal.

Tree shrews form a cohesive group of 19 species (Table 1.2) confined entirely to South and south-east Asia. None of the five genera covers the entire geographical range of the order; the genus Tupaia is by far the most widespread of these. The greatest number of species is found on the island of Borneo. This concentration is believed, in part, to be a consequence of the great size of the island and the resulting wide range of available habitats. But it is also possible that Borneo was the centre from which the adaptive radiation of modem tree shrew species began (Martin, 1984). Borneo was also joined to the Asian land mass for longer periods of time during the most recent Ice Age, enabling more species to migrate to it than to present-day offshore islands, such as many of those of the Indonesian archipelago.

Table 1. 2. Taxonomic summary of the
Asian tree shrews (Wilson, 1993)
Genus

Number of species

Family Tupaiidae
Anathana
Dendrogale
Ptilocercus
Tupaia
Urogale
Total


1
2
1
14
1
19



1.3 Geographical Coverage - Return to Top of Page | Table of contents

The Eurasian land mass, spreading halfway around the globe, comprises the world's largest land mass. This region covers two major biogeographical realms - the Palaearctic and Indomalayan. Included in this vast region are a wide range of habitats, ranging from tundra to tropical rainforest and including coniferous and deciduous forests, prairie and dry steppes, Mediterranean scrub vegetation and desert conditions.

For the purpose of this Action Plan the Eurasian region is seen to extend from the Great Blasket Island, West Ireland (10'32'W) to the Diomede islands in the Bering Straits (169'E), and from latitude 80'N (well inside the Arctic Circle) to Pamana on the island of Roti (Indonesia) in the Timor Sea (10'59'S) (see Map 1.1). Selected countries of North Africa (Morocco, Algeria, Tunisia, Libya and Egypt) are also included in this review as the range of a number of threatened shrew species extends across both North Africa and Eurasia.

In addition to the extensive land mass considered, a large number of islands are covered in this review. This includes all of the islands in the Mediterranean Sea, Socotra (Yemen) in the Gulf of Aden, the Andaman and Nicobar Islands (India), all of the islands in the Indonesian archipelago (including New Guinea), the Philippines, Hainan (China), Hong Kong (UK), Taiwan, Japan, Sakhalin Island (Russia) in the sea of Okhotsk, and the Kuril Islands (Russia). Although lying outside of the geographical limits outlined above, the Canary Islands (Spain), Madeira (Spain) and the Azores (Portugal) are also included within this review. Excluded are the islands of the Pacific Ocean, the Seychelles, Maldives and Chagos Island (UK).

Map 1.1. Region covered by this publication, showing Eurasian and North African counties


1.4 The lUCN/SSC Insectivore, Tree Shrew and Elephant Shrew Specialist Group (ITSES) - Return to Top of Page | Table of contents

The IUCN Species Survival Commission now has 104 Specialist Groups covering a wide range of taxonomic groups and conservation techniques worldwide. The common objective of these groups is to provide technical advice and guidance to the world conservation community (usually taking the form of governments and member organizations of IUCN) on the conservation of the species within their brief. One of the main activities of all taxafocused Specialist Groups is to prepare Action Plans which outline the conservation priorities for their species.

This Action Plan covering Eurasia is the second in a series of regional Action Plans being prepared by ITSES. An Action Plan for the Conservation of African Insectivora and Elephant Shrews was published in 1990 (Nicoll and Rathbun, 1990). A third action plan is currently in Dreparation for the Insectivora of the Americas.

Although the Species Survival Commission carried out some work on the Insectivora during the early 1980s, the Specialist Group in its current form was re-established in 1986. Its brief was also extended at the time to include the Scandentia and Macroscelidea. A list of current members is included as Appendix V.

In addition to providing a forum for expert review and discussion, a crucial role for ITSES is in the development and promotion of conservation projects, as well as the identification of potential funding sources. In this role, ITSES has already had some success in promoting conservation action for a number of species as well as increasing public and scientific awareness for the conservation needs of species within its brief. Wherever possible these projects will be fully integrated within other larger and more broad-based habitat protection programmes.

One of the major difficulties encountered in promoting the need for additional actions is that few insectivores, tree shrews or elephant shrews are of direct economic or even aesthetic value for mankind. Yet it is recognised that these are not 'insignificant' species, since they play a critical role in maintaining ecological diversity - not only in the role they play as key predators of invertebrates and as potential prey to a wide range of other species, but also in terms of their genetic diversity and the wide range of habitats and niches to which they have adapted. As research continues to unfold many fascinating aspects of these species' ecology it is essential that the habitat requirements and conservation status of these species is also better realised. Only then can measures be taken to identify and protect any threatened species.

In addition to its field and awareness activities, the Group also produces an occasional newsletter which aims to share information among the researchers working on the conservation of these poorly-known species. The Group now includes some 34 members, among them small mammal ecologists, scientists working in universities, zoological gardens and natural history museums, as well as interested amateur naturalists. It is not the Group's intention to be an exclusively scientific-based community; membership is open to anyone with a commitment to the conservation of those species which fall within the brief of the Group. Additional information on ITSES may be obtained by writing to the Chairman, or directly to the SSC Secretariat in Gland.


1.5 Threats Facing Eurasian Insectivores and Tree Shrews - Return to Top of Page | Table of contents

Unlike the majority of other mammalian groups few insectivores or tree shrews are subject to direct human interference through persecution. Although a few species of insectivores were once hunted for their valuable and highly prized fur (principally the European mole Talpa europaea and the Russian Desman Desmana moschata), this practise is no longer widespread and does not represent a threat to extant species. European moles are still considered a pest species in some countries, but this tends to apply only to regions of highly developed agriculture (see Stone, 1989 for overview).

A highly specialised species, the threatened Russian desman (Desmana moschata), shown here with the late Gerald Durrell, represents the plight of all semi-aquatic insectivores in the Eurasian region. (Photo by John Hartley)

The most important single reason for the decline of whole species and genera is probably habitat destruction. This takes many forms in Eurasia, each affecting a wide range of species. In western Europe, for example, removal of hedgerows, an ever-expanding road network, increasing cultivation with large scale additions of fertilizer and pesticides, and drainage of wetlands is having a noticeable impact on the number and distribution of many species. Increasing pollution of freshwater resources, combined with the construction of hydroelectric dams and canals play havoc on aquatic species such as the desmans and water shrews.

In south-east Asia, human encroachment into tropical forests either as a result of logging or slash-and-burn cultivation is destroying prime habitat for many species, including a large number of insectivores and tree shrews. Wetland drainage is also a major continuing problem in south-east Asia. In the long-term, such processes lead to habitat fragmentation and isolation of small, vulnerable populations.

Finally, for the vast majority of species under consideration in this Action Plan, one of the most worrying points is how little is actually known about the great majority of species. For these, the lack of data on basic ecology, distribution and conservation status is a major concern since it makes it more difficult to identify actions that might help detect impending threats to a given species and its habitat, and enable remedial action to be taken.


1.6 Rationale and Objectives of the Action Plan - Return to Top of Page | Table of contents

Insectivores and tree shrews are not considered among the most charismatic animals. Many people are not even aware of their existence. For these reasons, threats to insectivores and tree shrews often go unnoticed until it is too late to act. The present Action Plan for Eurasian Insectivora and Scandentia has been compiled to address this oversight.

In presenting this information, it is recognised that the Action Plan has many limitations. The secretive and often nocturnal nature of a great many of the species covered in this report has meant that few details are known on the natural history, ecology or conservation status of the majority of species. However, within the limits imposed by the current lack of information, it is firmly believed that this Action Plan has an important role to fulfil. Previous experience with the publication of such Action Plans supports this: the 1986 IUCN Red List of Threatened Animals (IUCN, 1986), for example, included just eight species of Insectivora. Following the publication of the Action Plan for African Insectivora and Elephant Shrews, 23 new species were added to this list when published again in 1990 (IUCN, 1990). More important, many worthwhile field programmes and related activities have arisen from this exercise, demonstrating the value of such an activity.

One of the principal objectives of this Action Plan, therefore, is to assess the current status of the Eurasian Insectivora and Scandentia. Within its brief, there are some 200 species; "satisfactory" information is thought to exist for maybe just a dozen of these. For many, a single museum specimen represents our total knowledge of the species. At the outset of this exercise, just five species were recognised as threatened in some way: Podogymnura truei, Crocidura tenuis, C. zimmermanni, Desmana moschata and Galemys pyrenaicus. In publishing this Action Plan, which applies a new series of criteria for defining a species' conservation status (IUCN, 1995), a total of 68 species has been identified as being in need of some form of protection, while another six require further research in order to assess their status (see Chapter 4 for further details).

In addressing these issues, this Action Plan provides a concise review of what is known about the taxonomy, distribution and conservation status of all members of the Insectivora and Tupaiidae in Eurasia. Information on taxonomy, distribution and recommendations has been obtained from a wide range of published sources (see References), unpublished reports and by direct communications with members of ITSES. To assist and encourage further investigations of these species, a brief description of each is included, together with pertinent notes on behaviour and ecology which might assist future researchers in locating and identifying these species.

In publishing this account - and recognising its many weaknesses at the present time - an appeal is made to scientists, members of other SSC groups and the wider public for more information on Eurasian insectivores and tree shrews.

In summary, the principal objectives of this Action Plan are to:

  • summarise information on the taxonomic status, distribution, and conservation status and requirements of Eurasian Insectivora and Scandentia;

  • prioritise species in terms of the need for conservation action;

  • prepare the groundwork for the preparation of a list of priority conservation projects for Eurasian Insectivora and Scandentia (see, for example, Appendix I and II);

  • stimulate further action - particularly field surveys of poorly-known species - in order to assess distribution and conservation status and to identify remedial action where appropriate;

  • promote and maintain 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;

  • liaise and cooperate with ongoing conservation efforts throughout Eurasia so that, when appropriate, recommended and approved actions by ITSES can be incorporated within existing or intended projects;

  • promote and encourage universities, associated institutes and expeditions, which are often of considerable importance by stimulating interest and research related to conservation; and

  • create and increase 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.






  • CITATION:
    IUCN. 1995. Eurasian Insectivores and Tree Shrews - Status Survey and Conservation Action Plan. (Compiled by Stone, R. David, IUCN/SSC Insectivore, Tree Shrew and Elephant Shrew Specialist Group). IUCN, Gland, Switzerland. vii + 164 pp. ISBN 2-8317-0062-0


    Online version: http://members.vienna.at/shrew/itsesAP95-cover.html

    Copyright © 1995 International Union for Conservation of Nature and Natural Resources


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