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Herpetofaunal surveys of the Tana River Primate National Reserve were conducted between December 1998 and January 2002 to generate a species list. Systematic search–and–seize, visual encounter survey and pitfalls with drift fence methods were used. Additional data derived from the collection of the National Museums of Kenya and the literature were also used. A total of 40 species comprising 16 amphibians (all anurans), and 24 reptiles (14 lizards, 1 crocodile, 8 snakes, 1 tortoise) were recorded.
Based on visual sightings and camera-trap photographs, an unusual form of giant sengi or elephant-shrew in the genus Rhynchocyon is identified from the Udzungwa Mountains of south-central Tanzania, which are already known for their extremely high biodiversity and endemism. This unique sengi appears to occur only in the Ndundulu, Mount Luhomero, and, possibly, Mwanihana forests and may therefore be of considerable conservation concern. A full description of this taxon, including formal naming, must await the collection and analysis of voucher specimens, which probably will take many months. In the meantime, it is important that conservationists focussing on the Eastern Arc Mountains be aware of the occurrence of this potentially new Rhynchocyon and field biologists participate in gathering additional information, especially on its distribution.
The ovoviviparous Kihansi spray toad Nectophrynoides asperginis is known from only one locality in the Udzungwa Mountains, Tanzania. At the time of discovery in 1996 the species occurred in a spray wetland habitat of about 4 ha maintained by spray from falls on the Kihansi River. River flow was diverted for hydropower production in late 1999, causing the habitat to desiccate, threatening the toad population and other plants and animals dependent on the spray wetland habitat.
We conducted field studies from January 2001 to November 2002 in 12 visits, with additional counts through to June 2003. Here we report on the changes in population numbers in the light of the mitigation measures introduced from 2001 in an attempt to maintain a habitat suitable for the Kihansi spray toad. Some data on life history are presented. This small toad is now restricted to an area of less than 2 ha. Due to a reported population crash in late 2003, variously attributed to pesticide use upstream, chytrid fungus, or safari ants (Dorylus sp.), the Kihansi spray toad may be effectively extinct in the wild. The actual cause of the population crash is not known.
The dragonfly fauna of the Rufiji District was studied during several field trips in 2001–2003 covering the rainy and the dry season. A total of 73 species was recorded by capture with net and visual identification of imagos. Ceriagrion mourae was seen for the first time since its description from Mozambique in 1969. Ceriagrion mourae, Teinobasis alluaudi, Gynacantha immaculifrons, Paragomphus magnus and Paragomphus sabicus are first records for Tanzania. Coryphagrion grandis, Ceriagrion mourae, Teinobasis alluaudi and Hadrothemis scabrifrons are globally endangered habitat specialists confined to coastal forests of Eastern Africa.
The majority of the species are common and widespread and inhabits the Rufiji River and its floodplains, while a smaller proportion are only found in permanent streams draining into the Rufiji or in forest habitats. The high overall species richness is a result of the variety of habitats and their connectivity, combined with the dynamics of the floods. The habitat specialists found in Ngumburuni forest and in the forests of the Kichi and Kiwengoma Hills are globally endangered species and require special attention with regard to conservation.
Swarm-raiding army ants are extremely polyphagous nomadic predators inhabiting tropical forests. They are considered keystone species because their raids can regulate the population dynamics of their prey and because a plethora of both invertebrate and vertebrate species are obligatorily or facultatively associated with them. Field observations and mathematical modelling suggest that deforestation and accompanying forest fragmentation cause local extinctions of the neotropical swarm-raiding army ant Eciton burchellii which in turn have negative effects on its associated fauna. The aim of this study was to examine whether afrotropical army ants are affected by forest fragmentation in the same way. Surveys of Dorylus (Anomma) molestus colonies were carried out in forest fragments of different sizes and in the matrix habitat at two sites in Eastern Kenya, along the Lower Tana River and in the Taita Hills. There was no significant relationship between the presence of D. molestus, forest patch size and distance to the nearest neighbouring patch at either of the sites. Colonies were often found outside the forest and can survive long enough in dry scrubland areas to reach new forest patches as far as 2 km away. We conclude that populations of this army ant species are less vulnerable to fragmentation than those of the neotropical E. burchellii, and that D. molestus can survive better in matrix habitat between forests because of several key differences in the foraging and nesting behaviour of the two species. Finally, we present a simple scenario describing the complex D. molestus population dynamics along the Lower Tana River and discuss the implications of our findings for conservation-oriented management of the two forest systems.
Growth rings of 19 tree species obtained from the Tana riverine forests in Kenya were studied for potential usefulness in dendrochronology. Among the growth ring characteristics used to qualitatively evaluate the potential usefulness of each species for dendrochronology included: distinctiveness of ring boundaries, ring circuit uniformity, ring wedging and ring sensitivity. Five species were identified as having the most desirable growth ring characteristics and therefore presented the best opportunity to crossdate ring width series among different trees. Crossdating among different trees would lead to the development of tree ring chronologies. These species included Acacia elatior, Acacia robusta, Tamarindus indica and Newtonia hildebrandtii, common on inactive levees occurring toward the edge of the floodplain, and Rinorea elliptica, an understory species found on levees. The timing of growth ring formation and exogenous factors responsible for its formation are yet to be identified. Drought conditions during the low river flow months of August and September are thought responsible for initiation of ring formation as these species grow in a semi-arid region and are thus entirely dependent on ground water.
The genus Aloe is common in Kenya, with about 60 taxa recognised. Observations from this study indicate that most of the taxa have a restricted distribution, with only Aloe secundiflora var. secundiflora being widespread in the country. The diversity patterns indicate a high concentration of taxa in three areas that are identified as Aloe hot spots and thus of high priority for conservation of the genus: The Kulal–Nyiro–Ndotos–Marsabit area in the north, the Taita–Shimba Hills zone to the southeast and the Naivasha–Baringo area in the Rift Valley. Most of the microendemic taxa are concentrated in the Kulal complex, a few in the Taita complex while the Naivasha complex includes mainly the widespread ones. Based on the computed Extent of Occurrence (EOO) and the threats to individual populations of endemic taxa about 36% were assessed as being Critically endangered, 32% as Endangered, 12 % as Vulnerable, 12% as being Near Threatened and 8% of Least Concern, according to IUCN Red Listing Criteria.
To assess plant uses and use values in Uluguru Mountains a study was carried out using household surveys and interviews on various uses of the plants. Descriptive statistics and use-value analysis techniques were used in data analysis. Of the plant species identified, 92% were used for fuel wood and 83% were used for construction materials. A significant difference in use values among the species was realized. Newtonia buchananii had the highest use value of 2.81 where as Piper capense had the lowest use value of 0.08. Villagers know which tree species are best for building poles or good as fuel wood, which wild fruits are edible and which are good for medicine. This knowledge is an important ingredient in the ongoing effort to reverse the trend of environmental degradation in the area.