Habitat assessment for a rare, arboreal forest mammal, the tree hyrax Dendrohyrax arboreus

Recent findings have suggested that there has been a change in the structural nature of forests in the Eastern Cape, South Africa, which explains decreases in forest fauna. One of these (rare) forest species is the tree hyrax Dendrohyrax arboreus, a nocturnal, arboreal folivore, which makes use of cavity‐bearing trees as dens. However, a conflict exists between the use of forest resources and in protecting habitats for the tree hyrax. In order to design appropriate management strategies, conservation authorities and forest managers require information regarding the specific habitat requirements of fauna in their forest, particularly those that are already threatened by resource use. The aims of this study were thus: (i) to characterise the den trees of D. arboreus, (ii) to determine whether D. arboreus selects for certain den tree characteristics (i.e. relative to the abundance of that characteristic); and (iii) to develop a habitat assessment model for D. arboreus. The tree hydrax was found to select for den trees with particular characteristics: seven tree species were selected as den trees, which were usually the tallest trees in the canopy (4–8 m). Den trees were usually only partly decayed, with multiple cavity entrances and trunk angles of between 45° and 68°. Cavity entrance and orientation did not appear to play a role in den tree selection by D. arboreus. A function which discriminated between den trees and non‐den trees was calculated, and can be used to determine the suitability of a tree as a den for a tree hyrax (and thus to prevent it from being removed during commercial logging operations), or to assess the suitability of an area for habitation by tree hyraxes. This model can therefore help to alleviate the conflict between forest conservation managers and resource users in the Eastern Cape.     

Habitat use and ranging behaviour of tree hyrax, Dendrohyrax arboreus, in the Virunga Volcanoes, Rwanda

Habitat use and ranging behaviour of tree hyrax were investigated by radio-tracking in the Parc National des Volcans, Rwanda. Individuals were predominantly arboreal and showed a daily pattern of vertical movement, being found highest in the canopy at night. Hyrax often spent the night in tree cavities and spent the day resting on branches. Habitat use is discussed in terms of thermoregulation and predator avoidance. Tree selection, modelled by logistic regression analysis, was most influenced by shelter properties. These criteria were best satisfied by large, cavity-forming Hagenia abyssinica , which were preferentially used. Tree hyrax population density was potentially limited by the availability of shelter. Home ranges were identified by minimum convex polygons for ten individuals. Total area and number of trees used were positively correlated with body mass, whilst the core area was negatively correlated with tree density. Ranges were not stable over the 4-month tracking period. There was considerable overlap of core areas between individuals. Core areas of mature males encompassed those of several females but no evidence of adult male range overlap was found. Female core areas tended to overlap with individuals of different ages. Male–female pair bonds were observed but the commonest association was parent–offspring.     

Activity patterns and feeding behaviour of the tree hyrax, Dendrohyrax arboreus, in the Parc National des Volcans, Rwanda

Activity patterns of Dendrohyrax arboreus were investigated by direct observation of a habituated population in the Parc National des Volcans, Rwanda. Of seventeen animals caught, four were males and thirteen were females. Of the population, 17% were juveniles. Population estimates from transects indicated a biomass of 23.3 kg/ha. Radio-tracking of ten individuals showed bimodal activity patterns, with peaks after dusk and later in the night for males and during the day in females. Hyrax were active 16% of the time. Feeding was the dominant activity and mature leaves of Hagenia abyssinica were the most important food. Travelling within and between trees occupied 4% of the time and occurred predominantly during daylight hours. Calling behaviour was markedly seasonal, being most pronounced in the dry season when hyrax called regularly in the early evening, and often a second time late at night. During the rains, calls were infrequent and unpredictable, tending to occur in the second half of the night. There was no correlation between weather or lunar conditions and calling behaviour. The ecological strategy of tree hyrax in terms of metabolic rate, thermoregulation and energy conservation is discussed in the light of their activity and feeding behaviour.     

Gross Nitrogen Turnover of Natural and Managed Tropical Ecosystems at Mt. Kilimanjaro,Tanzania

In our study at Mt. Kilimanjaro, East Africa, we quantified gross rates of ammonification, nitrification, nitrogen immobilization, and dissimilatory nitrate reduction to ammonium in soils across different land uses, climate zones (savanna, montane forest ecosystems, extensive agroforest homegarden, and intensively managed coffee plantation), and seasons (dry, wet, and transition from dry to wet season) to identify if and to what extent conversion of natural ecosystems to cultivated land has affected key soil microbial nitrogen turnover processes. Overall variation of gross soil nitrogen turnover rates across different ecosystems was more pronounced than seasonal variations, with the highest turnover rates occurring at the transition between dry and wet seasons. Nitrogen production and immobilization rates positively correlated with soil organic carbon and total nitrogen concentrations as well as substrate availability of dissolved organic carbon and nitrogen r > 0.67, P < 0.05), but did not correlate with soil ammonium and nitrate concentrations. Soil nitrogen turnover rates were highest in the montane Ocotea forest (ammonification 29.84, nitrification 12.67, NH₄ ⁺ immobilization 38.92, NO₃ ^? immobilization 10.74, and DNRA 1.54 µg N g^?1 SDW d^?1) and progressively decreased with decreasing annual rainfall and increasing land-use intensity. Using indicators of N retention and characteristics of soil nutrient status, we observed a grouping of faster, but tighter N cycling in the (semi-) natural savanna and Ocotea forest. This contrasted with a more open N cycle in managed systems (the homegarden and coffee plantation) where N was more prone to leaching or gaseous losses due to high nitrate production rates. The partly disturbed (selected logging) lower montane forest ranged between these two groups.     

Diverging diversity patterns of vascular plants and geometrid moths during forest regeneration on Mt Kilimanjaro, Tanzania

Aim This study investigates diversity patterns of vascular plants and plant‐feeding geometrid moths during montane rain forest regeneration in relation to the biogeographical and historical conditions of Mt Kilimanjaro. Location Investigations were undertaken on the south‐western slopes of Mt Kilimanjaro at altitudes between 2075 and 2265 m. Methods Thirteen plots were selected for this study. Four of these were situated in the middle of large clearings (> 1000 m²), three in secondary forest, two in mature forest remnants surrounded by secondary forest and four plots within continuous closed mature forest. Vascular plant species were recorded in an area of 20 × 20 m². Geometrid moths were attracted using lamps placed inside reflective gauze cylinders. Results Ninety‐three species of vascular plants were recorded on the plots. Plant diversity increased in the course of forest regeneration from clearings and secondary forest to mature forest remnants and mature forest. This increase was visible in all vegetation strata as well as in the species number of Dicotyledoneae. The diversity of geometrid moths conversely decreased from early to late successional stages. A total of 2276 Geometridae representing 114 morphospecies were included in the study. Local values of Fisher's α varied from 10.3 to 18.3 on clearings and in secondary forest, whereas they remained below 8.0 in mature forest and mature forest remnants. There was a significant negative correlation between the diversity of Geometridae and the number of dicots, and of plant species in the shrub layer. Main conclusions Contrary to an expected positive correlation between the diversity of vascular plants and herbivorous geometrid moths, diversity patterns of these two groups are strongly diverging due to biogeographical and ecological factors differently affecting the two groups. The increase in plant diversity can chiefly be explained with an increase in epiphyte diversity which is related to the occurrence of suitable habitats in extensive moss layers on huge Ocotea usambarensis (Engl.) trees in the mature forest. The low diversity of geometrid moths in these forests may be connected to the isolation and relatively young age of the montane rain forests on Mt Kilimanjaro. Hence only a small number of moth species adapted to the cool and perhumid conditions within moist mature forest have so far immigrated into these habitats, and time was insufficient for the evolution of many new species.     

The evolutionary ecology of early weaning in Kilimanjaro,Tanzania

Public health recommendations promote prolonged breastfeeding of all children; however, parental investment (PI) theory predicts that breastfeeding will be allocated among a mothers'' offspring to maximize her reproductive success. We evaluated PI in terms of risk for weaning before age two among 283 children in Kilimanjaro, Tanzania. Results demonstrate: (i) a Trivers–Willard effect—high socioeconomic status (SES) females and low SES males were more likely to be weaned early; (ii) later-born children were less likely to be weaned early; (iii) higher birthweight children were less likely to be weaned early, and (iv) no effect of cattle (a source of supplementary milk) ownership. These associations were largely independent and remained significant in models controlling for potential confounders; however, the inverse association between early weaning and birth order lost significance in the model containing birthweight. These patterns were observed despite public health recommendations encouraging breastfeeding for at least two years.     

Impacts of climate and land use on N2O and CH4 fluxes from tropical ecosystems in the Mt. Kilimanjaro region,Tanzania

In this study, we quantify the impacts of climate and land use on soil N₂O and CH₄ fluxes from tropical forest, agroforest, arable and savanna ecosystems in Africa. To do so, we measured greenhouse gases (GHG) fluxes from 12 different ecosystems along climate and land‐use gradients at Mt. Kilimanjaro, combining long‐term in situ chamber and laboratory soil core incubation techniques. Both methods showed similar patterns of GHG exchange. Although there were distinct differences from ecosystem to ecosystem, soils generally functioned as net sources and sinks for N₂O and CH₄ respectively. N₂O emissions correlated positively with soil moisture and total soil nitrogen content. CH₄ uptake rates correlated negatively with soil moisture and clay content and positively with SOC. Due to moderate soil moisture contents and the dominance of nitrification in soil N turnover, N₂O emissions of tropical montane forests were generally low (<1.2 kg N ha^?1 year^?1), and it is likely that ecosystem N losses are driven instead by nitrate leaching (~10 kg N ha^?1 year^?1). Forest soils with well‐aerated litter layers were a significant sink for atmospheric CH₄ (up to 4 kg C ha^?1 year^?1) regardless of low mean annual temperatures at higher elevations. Land‐use intensification significantly increased the soil N₂O source strength and significantly decreased the soil CH₄ sink. Compared to decreases in aboveground and belowground carbon stocks enhanced soil non‐CO₂ GHG emissions following land‐use conversion from tropical forests to homegardens and coffee plantations were only a small factor in the total GHG budget. However, due to lower ecosystem carbon stock changes, enhanced N₂O emissions significantly contributed to total GHG emissions following conversion of savanna into grassland and particularly maize. Overall, we found that the protection and sustainable management of aboveground and belowground carbon and nitrogen stocks of agroforestry and arable systems is most crucial for mitigating GHG emissions from land‐use change.     

TOC, TON, TOS and TOP in Rainfall, Throughfall, Litter Percolate and Soil Solution of a Montane Rainforest Succession at Mt. Kilimanjaro, Tanzania

Organic nutrients have proven to contribute significantly to nutrient cycling in temperate forest ecosystems. Still, little is known about their relevance in the tropics. In the present study, organic C, N, S and P were analysed in rainfall, throughfall, litter percolate and soil solution of a montane rainforest at Mt. Kilimanjaro, Tanzania. The aim was to determine the amounts of organic nutrients in different water pathways and to assess the influence of forest disturbance on organic nutrients by comparing mature forests, secondary forests and shrub vegetation in clearings. Concentrations of all studied elements increased from rainfall to throughfall and litter percolate and then exhibited a rapid decrease in the mineral soil. Concentrations of organic P were above the detection limit only in the litter percolate. Organic N (ON) as a fraction of total N increased from 50% in rainfall (0.19 mg l⁻¹) to 66% (0.45 mg l⁻¹) in throughfall followed by a decline to 39% in the litter percolate (0.77 mg l⁻¹) of the mature forest. Similarly, proportions of organic S and P amounted to 43 and 34%, respectively, in the litter percolate in mature forest. For ON, this proportion further decreased to less than 10% in the soil solution. The latter was probably attributable to a high sorption capacity of the studied Andisols, which led to overall low organic element concentrations in the soil solution (OC: 1.2 mg l⁻¹, ON: 0.05 mg l⁻¹ at 1 m soil depth) as compared to other temperate and tropical forest ecosystems. Organic element concentrations were higher in litter percolate and soil solution under the clearings, but there were no differences in the relative contribution of these elements. Organic nutrient forms at Mt. Kilimanjaro appeared to be much less susceptible to leaching than their inorganic forms.     

Tales of a stitched anus: fictions,analytics, and personhood in Kilimanjaro,Tanzania★

This article revisits the fiction explored by Sally Falk Moore more than forty years ago that initiation among the Chagga-speaking people of Tanzania's Kilimanjaro region involved men having their anuses plugged and stitched to ensure complete digestion. It combines historical sources and contemporary fieldwork material on which it deploys an anthropological analytic adopted from Marilyn Strathern's account of the partible person of Melanesia. The move makes room for the Chagga concept of horu and investigates how this life force is converted and conveyed by means of different parts of the body, which emerge as both effects of and means for its transfers and transformations. It renders the person a composite of social relations that are objectified in his or her body, and constitute persons as husbands and wives, and male and female. Gender categories and positions are thus modes of being that emerge as effects of particular relations. These also involve bodily alterations, like the stitched anus, that channel horu in specific forms and in certain directions for particular purposes. The result is not a partible person, but a vectorial person that is a conduit of life force.     

Ultrastructure of the sternal glands inThrips validus uzel (Thysanoptera,terebrantia)

Summary The ultrastructure of the sternal glands of the males ofThrips validus is consistent with the hypothesis that they are involved in pheromone production. The secretory cells, which are strongly modified epidermal cells, are characterized by the abundance of mitochondria and the presence of agranular, tubular endoplasmic reticulum (ATER) and microbodies. Each of the numerous apical microvilli encloses one or several tubular extensions of ATER. Some mitochondria are in close contact with ATER tubules. The mitochondrial matrix is probably involved in the elaboration of the secretory product, which is extruded and possibly modified by the agranular reticulum. The secretion is sudanophilic, but not osmiophilic. No lipid droplets are found in the cytoplasm. After storage in the strongly dilated subcuticular space, the secretion is released by epicuticular ductules with a diameter of about 120 å.I should like to thank the staff of the EM laboratory of the Zoological Institute for technical assistance, especially the photographer, Mrs. M. Ullmann     

Capturing and toying with hyraxes (Dendrohyrax dorsalis) by wild chimpanzees (Pan troglodytes) at Bossou, Guinea

Chimpanzees (Pan troglodytes verus) were observed capturing and toying with western tree hyraxes (Dendrohyrax dorsalis, Order Hyracoidea) at Bossou, Guinea. An adolescent female carried one hyrax for 15 hr, slept with it in her nest, and groomed it. The captive was not consumed. Nearby adults ignored the hyrax. In another case, two adolescent males timidly inspected a small hyrax. These observations indicate that the chimpanzees at Bossou do not regard the hyrax as a prey animal, supporting the idea that lack of opportunity does not seem to be the only reason that chimpanzees do not consume an individual of a potential prey species.     

The impact of tree modification by African elephant (Loxodonta africana) on herpetofaunal species richness in northern Tanzania

In Africa, no other nonhuman animal fulfils the role of ecosystem engineers to the extent of the elephant. However, little is known about the relationship between elephant modified habitats and species composition of other animals. Our objective was to sample the herpetofauna within an Acacia habitat that varied in the degree of elephant impact. If elephant foraging was only modifying but not degrading or enriching the habitat, then herpetofauna species abundance and richness were predicted to be similar in elephant damaged and elephant excluded areas. We conducted this study at Endarakwai Ranch in northeastern Tanzania for 6 months in 2007 and 2008. We sampled herpetofaunal species richness and abundance within high, medium and low elephant damaged areas and in a plot that excluded elephants. Areas of heavy damage yielded higher species richness than the exclusion plot. Species diversity did not differ between the damaged areas and the exclusion plot. Frogs were more abundant in areas of high damage; in contrast, toads were found the least in high damage areas. The results support the notion that free ranging elephants influence herpetofaunal species distribution by creating habitat complexity through modifying the woodland area.