South-central Tanzania Research Articles

Checklist of mammals of the Udzungwa Mountains of Tanzania

We present a checklist of mammals of the Udzungwa Mountains of south-central Tanzania (7°40′–8°40′ S and 35°10′–36°50′ E; Figure 1). The area (10,000 km2) contains the largest moist forest blocks of the Eastern Arc Mountains, a chain of ancient massifs partially covered in rainforest (Lovett and Wasser 1993), which is of outstanding importance for biodiversity conservation (Myers et al. 2000, Burgess et al. 2007). The area is also vulnerable to human exploitation because of the relatively small size of the forests, severe fragmentation (Brooks et al. 2002) and a lack of effective conservation management. The biodiversity importance of the Udzungwa Mountains is well reflected in the mammalian fauna (Kingdon and Howell 1993).

The status of Otomys orestes dollmani Heller, 1912 (Muridae: Otomyinae), a rodent described from the Mathews Range, central Kenya

Morphological and morphometric comparisons of Otomys orestes dollmani, known only from Mount Gargues in the Mathews Range, central Kenya, indicate that the taxon is a valid species distinct from other African forms under which it has been previously synonymized (O. irroratus, O. orestes, O. tropicalis). Based also on these comparisons, the morphological recognition and distribution of O. orestes (including thomasi Osgood) are further clarified in relation to O. tropicalis (including elgonis Wroughton) in Kenyan mountains and O. typus proper in Ethiopian highlands; another taxon relegated to junior synonymy within O. typus, O. uzungwensis Lawrence and Loveridge from south-central Tanzania, is resurrected to species. Certain traditional characters used in Otomys taxonomy, in particular molar lamination, demonstrate conservative patterns of variation that complement spatial structure derived from morphometric analyses of craniometric data and that vindicate their continued utility in delimiting species. We argue that uncritical emphasis of polytypic species, applied following the biological species concept during the latter 1900s, has led to chronic underestimation of species diversity of Otomys confined to the Afromontane Biotic Region in eastern Africa, in particular those populations that inhabit afroalpine environments.

Sanje Mangabey Cercocebus sanjei Kills an African Crowned Eagle Stephanoaetus coronatus

We present the first ever reported observations of a hunting African crowned eagle Stephanoaetus coronatus being killed by a primate, in the Udzungwa Mountains of south-central Tanzania. An adult female eagle launched an attack on a young Sanje mangabey Cercocebus sanjei who was feeding in a tree, but was intercepted and bitten by an adult mangabey who was feeding nearby. The adult mangabey and the eagle then fell together 25 m to the forest floor below. The eagle subsequently died from her injuries, while the mangabey escaped and is thought to have survived. This rare event is briefly discussed in the context of previous accounts of primate-crowned eagle interactions.

A POTENTIALLY NEW GIANT SENGI (ELEPHANT-SHREW) FROM THE UDZUNGWA MOUNTAINS, TANZANIA

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.

Notes on Abbott's duiker (Cephalophus spadixTrue 1890) and other forest antelopes of Mwanihana Forest, Udzungwa Mountains, Tanzania, as revealed by camera-trapping and direct observations

The Udzungwa Mountains of south-central Tanzania are part of an internationally outstanding area for biodiversity. This is reflected in the mammalian fauna and particularly in the forest antelopes: at least five species co-exist, including the Tanzanian endemic Abbott's duiker (Cephalophus spadix True 1890). Information on forest antelopes from Mwanihana Forest, one of the largest forest blocks within the Udzungwa Mountains, was collected by means of camera-traps and field observations. Eighty photographs of four antelope species were collected during 197 trap-days from four camera-trap sites. Seventy-one sightings were recorded during systematic counts and random survey walks for a total of 150 days of fieldwork. Results include the first photographs in the wild of Abbott's duiker, with one individual caught while holding what appears to be a frog in its mouth. The most photographed and sighted species was the Harvey's duiker (Cephalophus natalensis harveyi Thomas 1893), followed by the suni (Neotragus moschatus von Dueben 1846). Least photographed were Abbott's duiker and bushbuck (Tragelaphus scriptus Pallas 1766). The study shows the usefulness and potential of camera-traps to collect information on the presence, relative abundance and habits of antelopes in densely forested areas.

Demographic Variation Among Udzungwa Red Colobus in Relation to Gross Ecological and Sociological Parameters

We evaluated variation in group size and composition of Udzungwa red colobus (Procolobus gordonorum) in relation to gross-habitat and sociological parameters. The endangered species is endemic to the Udzungwa Mountains and nearby forests in the Kilombero Valley of south-central Tanzania. We counted 63 groups in 10 forests, ranging in altitude from 250 to 1,800 m. Group size ranged from 7 to 83 (x = 36.3) individuals and adult sex ratios (females/male) ranged from 1.5 to 7.3 (x = 3.5), excluding solitary individuals. Group size was influenced by several habitat parameters, including tree density, degree of deciduousness, and forest size. Groups were largest in large blocks of mature, moist, mixed evergreen and semideciduous forests, but group size is not correlated with altitude. Groups in a highly degraded forest appeared to have fission-fusion societies. The effect of habitat quality on age-sex composition of groups was most apparent in natality and less so in survivorship of adult females and juveniles. The number of adult males in groups accounted for 50% of the variance in group size and 34–39% of the variance in numbers of adult females in groups. Habitat quality affects natality more than demographic parameters do. Groups with a low proportion of adult females had greater juvenile survivorship, perhaps because of lower food competition between these two classes. We proffer hypotheses based on our study and previous intertaxonal comparisons to explain cause and effect relationships between habitat quality and demography. Finally, our study demonstrates the importance of large blocks of old-growth forest to the conservation of Udzungwa red colobus, and we make recommendations for conservation and research.

Evaluation of chemical and physical-morphological factors as potential determinants of Biomphalaria pfeifferi (Krauss, 1848) distribution.

This study was carried out in five sites along a small perennial river system in south-central Tanzania, which had been identified as the focus for transmission of intestinal schistosomiasis in the area. Malacological surveys preceding the study showed a focal distribution of Biomphalaria pfeifferi, intermediate host snail of Schistosoma mansoni, the snails being present in three sites but absent from the other two sites. The objective of this study was to evaluate to what extent chemical and/or physical-morphological factors determine the distribution of B. pfeifferi between these five sites. It was found that none of the chemical constituents in the waters examined were outside the tolerance range of B. pfeifferi snails. Moreover, the composition of water from B. pfeifferi-free sites was not different from that in those sites where snails occurred. Furthermore, none of the physical-morphological constituents seemed likely to be a determinant for the absence of B. pfeifferi. In view of these findings, and those of previous studies, it is concluded that the focal distribution of B. pfeifferi cannot be associated with a single environmental factor and is rather the result of more complex interactions of habitat factors.

Spatial microhabitat selection by Biomphalaria pfeifferi in a small perennial river in Tanzania

A study was carried out in the Mlali river in south-central Tanzania with two aims. First, to determine microhabitat availability in two sites (A and B) with respect to water depth, water velocity and dominant substratum type. Second, to assess microhabitat use by Biomphalaria pfeifferi, the intermediate host snail of intestinal schistosomiasis and to investigate whether these snails show preferences for certain microhabitats. The two sites differed significantly with respect to width, water depth, water velocity and substratum composition. It is suggested that the absence of B. pfeifferi from site B is mainly associated with the high water velocities at that site, where 62% of the measurements exceeded30 cm s-1. In site A, the microhabitat use by 327 B. pfeifferi snails was assessed by means of direct observation. No significant relationships were found between snail size and the habitat variables investigated, indicating that snail size appeared to be of no importance in spatial microhabitat selection. B. pfeifferi snails showed statistically significant preferences for shallow water (depth: 2–7 cm) and the preferred water velocities ranged between 12 and 21 cm s-1 with an estimated optimum at13.3 cm s-1. No statistically significant preferences for substratum type were found.

Stratigraphy and morphotectonics of Karoo deposits of the northern Selous Basin, Tanzania

AbstractLate Permian Karoo deposits of the northern Selous Basin in south-central Tanzania comprise conglomerates and diamictitic boulder beds of alluvial and scarp-foot fan origin. These merge with grey to greenish sandstones, siltstones and black shales of deltaic and lacustrine environments. Microflora assemblages indicate a late Permian age. Lateral changes and interfingering of various lithofacies units are common. Depositional development was controlled by syndepositional faulting and variations of gradients resulting from fault movements. The position of the fault scarp separating the basin area from the elevated basement horst to the west roughly corresponded with the present boundary between the Selous Basin and the Precambrian metamorphics of the Uluguru Mountains.The late Permian Karoo succession of this part of the Selous Basin apparently overlaps older Karoo deposits contained in the north-northeast trending narrow graben structures. It is therefore regarded as a new depositional event which was initiated by renewed tensional tectonism in late Permian time. During this tectonic episode the narrow early Karoo graben structures were expanded into much broader rift basins. Material eroded from the rift shoulders and associated highlands was literally dumped across the fault scarps, forming debris aprons and scarp-foot fans. Rivers emanating from the highlands formed large alluvial fans and, further afield, deltas issued into freshwater lakes.Some of these late Permian faults were rejuvenated by late Cretaceous to early Tertiary tectonism. Thermal waters circulating along fractures converted feldspars, biotites and hornblendes to prehnite. Further tectonic adjustments in mid Tertiary time led to the present-day morphology.

A new Forest Species of Phrynobatrachus (Anura: Ranidae) from Morogoro Region, Tanzania

AbstractA new species of moderate-sized Phrynobatrachus from the forests of the Uzungwe and Uluguru Mountains of southcentral Tanzania is described. It is distinguished by having dorsal asperities in both sexes and by a reddish-orange colouration on its digits and arms, this colour sometimes extending to the shoulders. The adult male lacks femoral glands and gular folds. Comparisons are made with other East African Phrynobatrachus species.