LEPIDOPTERISTS’ SOCIETY OF AFRICA EXECUTIVE COUNCIL Bennie Coetzer Acting President [email protected] Alf Curle Secretary [email protected] Alf Curle Treasurer [email protected] Bennie Coetzer Stock Custodian [email protected] Peter Roos Publicity [email protected] Mark C. Williams Conservation matters [email protected] Doug Kroon Editor [email protected] Martin Krüger Transvaal Museum [email protected] Steve Collins East Africa Branch [email protected] Alan Gardiner Zimbabwe Branch [email protected] Jonathan Ball Western Cape Branch [email protected] Torben Larsen West Africa Branch [email protected] Ernest Pringle Eastern Cape Branch [email protected] Reinier Terblanche North West Branch [email protected] Steve Woodhall Gauteng Branch [email protected] EDITORIAL Editor: Doug Kroon Scientific advisers: Mark Williams, Martin Krüger, Rolf Oberprieler, Stephen Henning, Henk Geertsema, Alan Gardiner, Dick Vane-Wright, Axel Hausmann. MEMBERSHIP The aims of The Lepidopterists’ Society of Africa are to promote the scientific study and the conservation of Lepidoptera in Africa, and to provide a communication forum for all people who are interested in African Lepidoptera. Metamorphosis, which is the official journal of the Society, publishes original scientific papers as well as articles of a less technical nature. Membership of the Society is open to all persons who are interested in the study of Lepidoptera. There is no geographical limit to membership. 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Box 477, Jukskei Park, 2153, South Africa, e-mail - [email protected] Covers: Panoramic view of Kaya Muhaka forest edge; inset: side view of Charaxes lasti September 2000 METAMORPHOSIS Occasional Supplement 4 1 __________________________________________________________________ PRELIMINARY SURVEY ON BUTTERFLIES AND MOTHS AND THEIR HABITATS IN TWO KAYA FORESTS OF THE KENYA COAST INGO LEHMANN a and ESTHER KIOKO b a Uferweg 30, 23996 Bad Kleinen, Germany b Department of Invertebrate Zoology, National Museums of Kenya, P.O. Box 40658, Nairobi, Kenya ABSTRACT:The forest stratification, plant, butterfly and larger moth diversity of Kaya Muhaka and Kaya Kinondo (Kenya, Coast, Kwale District) are described. Both Kayas have old secondary forest patches and are certainly not unmodified relics. The Lepidopteran fauna includes species not previously recorded from Kenya or from coastal Kenya and was diverse in Kaya Muhaka. The Shimba Hills were found to be the potential source for the butterfly faunas of both Kayas. Together, all three areas support c. 30% of the total Kenyan butterfly fauna. 23% are coastal endemics and only 1.6% of species have a central and western Africa distribution. In contrast, for example 18–21% of plant species with a central and western Africa (Guineo-Congolian) distribution occur in Kaya Muhaka. Butterfly conservation priority is recommended all habitats in the Shimba Hills and for nearby coastal forests. INTRODUCTION Objective The main aim of the 1994 and 1996–1998 field work was to study as intensively as possible two coastal forests1 south of Mombasa, namely Kaya Muhaka and Kaya Kinondo, with the hope of throwing some light on the butterfly and moth fauna and their habitats. For both Kayas, no equivalent survey exists. Most of the information and data presented here is based on our report (Lehmann & Kioko, 1998). All information collected is not yet completely analyzed. Therefore, the objective of this article is to give a preliminary survey of the Lepidoptera fauna and their habitats, namely the forest stratification and floristic composition. In addition to our report a comparison with the butterfly fauna of the Shimba Hills will be done here and is based on our assessment of the data published by Sevastopulo (1973/1974). The Shimba Hills were chosen for comparison because they are close to both Kayas, constitute the largest coastal forest block in Kenya south of Mombasa and are a potential source area. Distributions of butterflies and moths in the lowland forests of the Afrotropical region The Afrotropical Region (Crosskey & White 1977) has a butterfly fauna that consists of 301 genera and of some 3607 known species (Ackery et al. 1995). Of these c. 56% are restricted to forests (de Jong & Congdon 1993). 1 In this article the term “forest“ will be applied according to White (1983) for a continuous stand of trees with a canopy that varies in height from 10 m or more. The term “coastal forest“ will be used after Hawthorne (1993) for forest in the coast which is “ ... the land over the sedimentary (and intrusive volcanic) rocks of the coastal plains and plateau, to the east of the exposed basement complex land.“ 2 METAMORPHOSIS Occasional Supplement 4 September 2000 ___________________________________________________________________ Largely based on the publication by Carcasson (1964), Ackery et al. (1995) stated, that within this region, the greatest density of butterfly species occurs in the forests below 1500 m. These lowland forests are “very much poorer“ in species in eastern Africa, although their butterfly fauna shows “unmistakable affinities“ with the species rich western lowland forest fauna. The impoverishment of the eastern forests “must have been due to their extreme fragmentation and reduction during interpluvial phases ... and to the tenuous and shortlived character of recent connections with the western forest reservoir.“ The occurrence of numerous endemic species and distinct subspecies in the lowland forests of eastern Africa suggests that broad based links have only been possible in the remote past. 400 Forest butterfly species, of which 79 species are endemic, inhabit the “eastern African coastal forests“ (Burgess et al. 1998). For the Lepidoptera of the Afrotropical region major eco-geographic sub-regions were proposed by Carcasson (1964). The Sylvan sub-region, Lowland forest division, includes the Eastern sub-division (Coastal forest zone) which comprises all the lowland forest to the east of the eastern tablelands, from Kenya to Zululand (Natal, South Africa). In Kenya, lowland forests occur mainly along the coast and in western Kenya. Larsen (1991) stated that “870 or so“ butterfly species occur in Kenya and of these, c. 400 species could be found in the Kakamega area (western Kenya) alone. Only “a small group of species“ is found in all the forest zones from Senegal to coastal Tanzania and Kenya. But “a very large proportion“ of the coastal forest species are endemic to the East African coast, including few limited to the Kenya and/or Tanzania coast, and the bulk of these endemics have close relatives in the equitorial forests. Larsen mentioned that it would appear that there has been contact between forests of western Africa and the coastal forests at various times in the Miocene or early Pliocene, as well as at a more recent date, probably through southern Tanzania and Malawi. Lovett (1993) also discussed the links between the forests of western and eastern Africa and pointed out that they existed possibly only during wet periods and that the relatively stable and warm climate of the Indian Ocean during the last 2.3 Myrallowing the survival of western (Guineo-Congolian) relict endemic species. Collins & Larsen (1996) stated that “some 30 species have been added to the Kenyan list“. Congdon & Collins (1998) mentioned “approximate[ly] 895“ butterfly species for Kenya and listed 25 endemic species. Their figures indicate that Kenya has a substantially lower species richness compared with Tanzania where c.1370 species including 121 endemics occur and Uganda with c. 1242 species and 34 endemics. There is little knowledge about the distributions of moth species in the lowland forests of the Afrotropical region. Coastal Forests: their Status and Significance The coastal areas of East Africa and the western Indian Ocean contain some of the world’s richest ecosystems and provide valueable resources for over 30 million people, but the intensity and nature of human activities increasingly threatens their productivity and biological diversity (Lindén 1993; Richmond 1998). This is partly dfue to a high steady population increase (Goliber 1985). Today, the coastal forests of eastern Africa are a refuge for a wide variety of plant species (Brenan 1978; White 1983; Hawthorne 1993) and an important, highly threatened centre of endemism for plants, mammals, birds, reptiles, frogs, butterflies, snails and millipedes (Burgess et al. 1998). September 2000 METAMORPHOSIS Occasional Supplement 4 3 __________________________________________________________________ Kenya2 has the most diverse forests in East Africa (IUCN/WCMC, 1992). Its coastal forests support the highest diversities of flora (Beentje 1988; Robertson & Luke 1993; Wass 1995) and fauna (Bennun 1995; Waiyaki 1995; Bennun & Njoroge 1999). The flora is part of the Zanzibar-Inhambane regional mosaic (Moll & white 1978; White 1983). Coastal forests occupy c. 660 km2 in Kenya of which the largest is Arabuko-Sokoke with 370 km2, but the majority is smaller than 5 km2 (Burgess et al. 1998). They are located within 30-50 km inland from the Indian Ocean – except for those within the forest belt of the Tana River floodplain (Andrews et al.