Habitat suitability modelling to improve conservation status of two critically endangered endemic Afromontane forest bird species in Taita Hills,Kenya

Tropical montane forests are known to support many endemic species with restricted geographic ranges. Many of these species are however, faced with numerous threats, most notably from habitat loss and degradation, invasive alien species, and climate change. Examples include Taita Apalis and Taita Thrush. Taita Apalis (Apalis fuscigularis) and Taita Thrush (Turdus helleri) are species of birds listed as Critically Endangered by the Government of Kenya and the International Union for Conservation of Nature (IUCN). They are endemic to Taita Hills’ cloud forests in southeastern Kenya and protected under Wildlife Conservation and Management Act. As they face high risk of extinction, exploring their habitat suitability is imperative for their protection. To determine the current spatial distribution and the key ecogeographical explanatory factors and conditions affecting species distribution and indirect effects on species survival and reproduction, we employed Maximum Entropy (MaxEnt) modelling. This study was conducted in Ngangao and Vuria forests in June and July 2019 and 2020. Ngangao forest is gazetted as forest reserve and managed by the Kenya Forest Service whereas Vuria is non-gazetted and thus remains without official protection status. Ecogeographical explanatory variables; climatic, remote sensing-, LIDAR-, topography- and landscape-based variables were used in modelling and separate models were produced. 23 occurrence records of Taita Apalis and 30 of Taita Thrush from Ngangao and 21 of Taita Apalis from Vuria forests were used in the modelling. According to the models, less than 7% of the total area of Ngangao and Vuria forests was predicted as suitable habitat for Taita Apalis and Taita Thrush. This shows that these two species are more vulnerable to extinction from demographic stochasticity. Consequently, managing their habitats is critical for their long-term persistence. LIDAR-based canopy height range and elevation greatly influenced Taita Apalis distribution in Ngangao forest, with areas of high elevation (1620–1750 m a.s.l.) and having open middle-storey preferred. Elevation, slope and topographic wetness index (twi) were the major determinants of Taita Thrush distribution in Ngangao, where gentle sloping areas with moderately dry surfaces within high elevation (1620–1730 m a.s.l.) were favoured. Mean annual temperature, Euclidean distance to the forest edge, slope and land cover type greatly influenced the distribution of Taita Apalis in Vuria, with gentle sloping areas within forest interior made up of indigenous vegetation preferred. This study proposes reforesting open and degraded sites next to areas predicted as highly suitable for the two species; establishment of agroforestry belts based on indigenous trees on the boundaries of the two forests to reduce grazing and firewood collection pressure and enhance resilience to the edge effects; and enhancing forest protection through Participatory Forest Management.     

Trends in forest condition,threats and conservation action as derived from participatory monitoring in coastal Kenya

The coastal forests of Kenya are conservation priorities hosting high levels of biodiversity. Monitoring of biodiversity in these forests is therefore necessary to understand and reverse negative trends in good time. Using the Important Bird Area (IBA) monitoring framework, a participatory approach, state (habitat condition), pressure (threats) and response (conservation action) indicators of twelve coastal Kenya forest IBAs were assessed from 2004 to 2011. Trends for these indicators were assessed at six sites for which sufficient data existed: Arabuko‐Sokoke, Dakatcha Woodlands, Gede Ruins, Lower Tana River, Shimba Hills and Taita Hills, and baselines were described for remaining six. Changes were always small, but state deteriorated in Gede, Lower Tana and Shimba Hills, remained the same (unfavourable) in Arabuko‐Sokoke and Dakatcha, and improved in Taita Hills. Pressure reduced in Arabuko‐Sokoke, Dakatcha and Taita Hills, deteriorated in Lower Tana and Shimba Hills and remained the same (medium) in Gede. Response improved in Dakatcha, remained the same (medium) in Shimba Hills, and deteriorated in the rest. As there was an apparent overall deterioration in the forests assessed, improved management of the protected sites and increased conservation action through community engagement around protected areas and within the nonprotected IBAs are recommended.     

Important Bird Areas in Kenya

Bennun, L. & Njoroge, P. 2000. Important Bird Areas in Kenya. Ostrich 71 (1 & 2): 164–167.

The process of defining Important Bird Areas in Kenya has been underway since January 1995, with financial support from the Royal Society for the Protection of Birds. Literature review has proceeded in parallel with field surveys, which are still ongoing. Some 65 globally Important Bird Areas have so far been identified, and this total is likely to increase. Sites were intitially selected using the criteria of threatened species (37 sites) and congregatory species (15 sites). Additional sites were then identified for biome-restricted and restricted-range species, using information from the Bird Atlas of Kenya; these sites must form part of a regional set. Threatened species sites are concentrated in forests (on the coastal strip, in the central highlands and in western Kenya) and papyrus swamps. Congregatory-species sites are concentrated along the Rift Valley and the coast. The remaining sites are concentrated in semi-arid areas to the immediate north and east of the central plateau, and in highland forest on each side of the Rift Valley. No IBAs have yet been identified in the flat, arid north-eastern sector of the country. A large number of sites require additional protection and/or improved management. Particular priorities include several papyrus IBAs around Lake Victoria, among them Lake Kanyaboli and Yala and Sare Swamps, grassland pockets in Mungatsi and Nambale, Western Province; the Kakamega, South Nandi and North Nandi Forests; the increasingly fragmented coastal forests, including Arabuko-Sokoke Forest; and the Taita Hills. Information on the IBA process and its results is being distributed to decision-makers through a high-level IBA Advisory council, with encouraging intitial results.     

Woody plant communities of isolated Afromontane cloud forests in Taita Hills,Kenya

In the Taita Hills in southern Kenya, remnants of the original Afromontane forest vegetation are restricted to isolated mountain peaks. To assess the level of degradation and the need for forest restoration, we examined how forest plant communities and their indicator species vary between and within remnant patches of cloud forest. We used ordinal abundance data to compare plant communities in eight forest fragments. We also analyzed data on the diversity and abundance of trees in 57 0.1 ha plots to compare tree communities within and between the largest two of these fragments, Ngangao (120 ha) and Mbololo (220 ha). The extant vegetation of the Taita Hills at landscape scale consists of secondary moist montane to intermediate montane forest. There was a high species dissimilarity between fragments (69%). Variation in species composition coincided with an abiotic gradient related to elevation. At plot level, secondary successional species and species of forest edges were most abundant and most frequent. Inferred clusters of plots almost entirely coincided with the two forest fragments. Indicator species associated with forest margins and gaps were more frequent in the smaller of the two forest fragments, while indicators for the larger fragment were more typical for less disturbed moist forest. Abiotic site variability but also different levels of disturbance determine site-specific variants of the montane forest. Conservation efforts should not only focus on maintaining forest quantity (size), but also on forest quality (species composition). Late-successional rainforest species are underrepresented in the woody plant communities of the Taita Hills and assisting restoration of viable populations of cloud forest climax tree species is urgently needed.     

Molecular phylogeny of the endemic East African flightless grasshoppers Altiusambilla Jago, Usambilla (Sjöstedt) and Rhainopomma Jago (Orthoptera: Acridoidea: Lentulidae)

Abstract.  A molecular phylogeny of endemic flightless grasshoppers is presented for the three Lentulidae genera Altiusambilla Jago, 1981 , Usambilla Sjöstedt, 1909 and Rhainopomma Jago, 1981 based on DNA sequences (16S rRNA locus). Parsimony, distance and likelihood reconstructions were performed using different assumptions on sequence evolution. The generated phylogenies agree in almost all parts of the calculated trees and support the monophyly of the observed genera. It was shown that Usambilla and Rhainopomma are more closely related to each other, Altiusambilla being a separate clade. However, the investigated East African lentulid genera are clearly separated from South African taxa, underlining the monophyly of East African genera. Usambilla olivacea is re-established. Populations of Rhainopomma montanum from the Taita Hills of Kenya and from the West Usambara mountains of Tanzania are two separate species not closely related to each other. Rhainopomma samples from the North Pare mountains of Tanzania belong to a hitherto undescribed species.     

Flexible nest-site selection under anthropogenic habitat change in an Afrotropical understorey insectivore

Human activities impact upon natural habitats used by birds for breeding and foraging, and lead to changes in the composition and spatial distribution of predator communities, mainly through loss, fragmentation and disturbance of formerly pristine habitat. Yet possible fitness consequences of such changes through impacts on bird nest-site selection remain poorly known. Here we study nest-site selection and reproductive success of Placid Greenbuls Phyllastrephus placidus in the Taita Hills, southeast Kenya. We show that habitat features associated with nest-site selection by this insectivorous, open-cup-nesting bird species vary among forest fragments that are exposed to different levels of habitat disturbance. Such differences in sites selected for breeding result from a plastic response to fragment-specific conditions or may be driven by fragment-specific variation in the distribution and availability of certain habitat features. Given the overall high nest predation rates in our study area, we expected variation in nest-site selection to correlate with reproductive success and nestling condition, but detected no such relationship. Because predator density and nest predation rates may vary strongly in space and time, a better understanding of spatio-temporal variation in predator communities is needed to assess the possible adaptive value of nest-site selection strategies for reducing the high predation rates that are typical for this and many other open-cup-nesting tropical passerines.     

Experimental transplants reveal strong environmental effects on the growth of non‐vascular epiphytes in Afromontane forests

Transplant studies can provide valuable information on the growth responses of epiphytic bryophytes and lichens to environmental factors. We studied the growth of six epiphyte species at three sites in moist Afromontane forests of Taita Hills, Kenya. With 558 pendant transplants, we documented the growth of four bryophytes and two lichens over 1 yr. The transplants were placed into the lower canopy of one forest site in an upper montane zone, and two forest sites in a lower montane zone. Several pendant moss species grew very well in the cool and humid environment of the upper montane forest, with some transplants more than doubling their biomass during the year. Conversely, all transplanted taxa performed poorly in the lower montane zone, presumably because of the unfavorable combination of ample moisture with excessive warmth and insufficient light which characterizes the lower canopy in dense lower montane forests. The results demonstrate that pendant transplants can be used for monitoring growth of non‐vascular epiphytes in tropical forests. The starting weight of 0.25 g for pendant transplants worked well and can be recommended for future studies.     

The genus Aerotegmina (Orthoptera, Tettigoniidae, Hexacentrinae): chromosomes, morphological relations, phylogeographical patterns and description of a new species

The genus Aerotegmina Hemp is common on East African mountains. Two species are known and a third, A. taitensis n. sp., is described in this paper. A. kilimandjarica Hemp is widespread while A. shengenae Hemp is endemic to the South Pare Mountains and A. taitensis n. sp. is known only from the Taita Hills. Morphologically, and from their song, A. shengenae and A. taitensis n. sp. are closely related. In chromosome number A. kilimandjarica (2n?=?33) differs clearly from A. shengenae (2n?=?27). Data presented on other flightless Orthoptera suggest that the South Pare Mountains and the Taita Hills, both belonging to the geologically old mountain chain of the Eastern Arc, show a faunistic similarity not shared by any other mountain range in the area. The mechanisms that led to this phylogeographic pattern in flightless Orthoptera in the Eastern Arc Mountains of northern Tanzania and southern Kenya and the inland volcanoes are discussed. A key to the three Aerotegmina species is presented, as well as bioacoustical data of all species compared to the phaneropterine species Euryastes jagoi.     

Social Organization, Resource Management, and Child Nutrition in the Taita Hills, Kenya

A comparative and longitudinal ecological analysis is used to explore agricultural sources of variation in child nutritional status in the Taita Hills, Kenya. National policies, formal institutions, the natural environment, and the local-level social organization of agricultural resource access define the agrarian context within which distinct production strategies emerge. The effects of alternative production choices on child nutrition are neither consistent nor unidimensional, arguing for a rethinking of conventional approaches to food policy decision making.     

肯尼亚凤仙花属——新变种

报道了发现于东非肯尼亚塔易塔（Taita）地区亚乐森林（Yale Forest）的凤仙花属（Impatiens L.）一新变种,即：白花拟堇菜凤仙（I.pseudoviola Gilg var.alba G.W.Hu et Q.F.Wang）,该新变种与原变种拟堇菜凤仙（I.pseudoviola Gilg var.pseudoviola）的区别是：花冠纯白色,茎和叶柄均为浅绿色,植株整体缺乏紫色色素;花柄近无毛;低位侧生萼片与高位的侧生萼片近合生。     

Care and parentage in a skin-feeding caecilian amphibian

An exceptional form of parental care has recently been discovered in a poorly known caecilian amphibian. Mothers of the Taita Hills (Kenya) endemic Boulengerula taitanus provide their own skin as a food source for their offspring. Field data suggest that nursing is costly. Females found attending young had a lower body condition and fat body volume than nonbrooding and egg-incubating females, and the female condition decreased substantially during parental care. Most mothers and their eggs or offspring were found in close proximity to other nesting females, in high-density nest sites that enhance the potential for social interactions and highlighting the possibility of communal breeding. Parentage was investigated using Amplified Fragment Length Polymorphism (AFLP) genetic markers in 29 offspring from six litters guarded by putative mothers. Our data provide the first evidence of multiple paternity in a caecilian, implying that two fathers sired one litter. Some young from two litters had genotypes not matching the guarding female suggesting that not all offspring are cared for by their biological mothers. This study provides evidence for alloparenting in an amphibian with cost-intensive parental care. J. Exp. Zool. 309A:460-467, 2008. (c) 2008 Wiley-Liss, Inc.     

Diet composition of Xenopus borealis in Taita Hills: effects of habitat and predator size

Frogs in the genus Xenopus are ubiquitous in sub‐Saharan Africa, yet very little is recorded on their ecology. They are commonly found in anthropogenically disturbed habitats, but how do these compare to conspecifics from natural habitats? The diet of Xenopus borealis from three different sites in Taita Hills, Kenya was established based on a sample of 77 (54 females and 23 males) specimens from two disturbed and one pristine sites. Xenopus borealis from all the sites was found to be a dietary generalist, feeding predominantly on invertebrates. A total of twelve invertebrate orders both terrestrial and aquatic were recorded in addition to amphibian eggs, tadpoles and fish. Frogs from the pristine forest were smaller and had ingested more terrestrial prey items than frogs in the disturbed open habitat ponds. The stomach content (both by mass and quantity) was independent of body size. The results suggest that X. borealis is an opportunistic generalist predator which may be constrained by food availability in its natural habitat. However, disturbed habitats provide abundant food items which are enough to significantly increase the mean size of the population.     

Biogeography of the Shimba Hills ecosystem herpetofauna in Kenya

The Shimba Hills ecosystem along the south coast of Kenya is a key East African biodiversity hotspot.Historically, it is biogeographically assignable to the East African coastal biome. We examined the current Shimba Hills herpetofauna and their zoogeographical affinities to the coastal forests and nearby Eastern Arc Mountains biodiversity hotspots.The key studied sites included the Shimba Hills National Reserve, forest reserves, Kaya forests, and adjacent private land. Data on herpetofaunal richness were obtained from recent field surveys,literature, and specimens held at the National Museums of Kenya, Herpetology Section Collection,Nairobi. The Makadara, Mwele, and LongoMwagandi forests within the Shimba Hills National Reserve hosted the highest number of unique and rare species. Generally, the forest reserves and Kaya forests were important refuges for forestassociated species. On private land, Mukurumudzi Dam riparian areas were the best amphibian habitat and were host to three IUCN(Red List) EndangeredEN amphibian species, namely, Boulengerula changamwensis, Hyperolius rubrovermiculatus, and Afrixalus sylvaticus, as well as one snake species Elapsoidea nigra. Using herpetofauna as zoogeographic indicators, the Shimba Hills were determined to be at a crossroads between the coastal forests(13 endemic species) and the Eastern Arc Mountains(seven endemic species).Most of the Eastern Arc Mountains endemic species were from recent records, and thus more are likely to be found in the future. This 'hybrid' species richness pattern is attributable to the hilly topography of the Shimba Hills and their proximity to the Indian Ocean.This has contributed to the Shimba Hills being the richest herpetofauna area in Kenya, with a total of 89 and 38 reptile and amphibian species, respectively.Because of its unique zoogeography, the Shimba Hills ecosystem is undoubtedly a key biodiversity area for conservation investment.     

Spatial and temporal variation in fruit and fruit-eating birds in the Taita Hills,south-east Kenya

We studied the spatial and temporal variation in fruit abundance and frugivorous bird densities in a large-sized (135ha), a medium-sized (95ha) and five small-sized (each 2–8ha) forest fragments in the Taita Hills, Kenya. The large and medium patches were respectively divided into six and three plots, while the small patches were each treated as a single plot. A pilot analysis established that the plots were sufficiently independent. Three separate census-rounds were conducted in all plots. We found significant variation in fruit density amongst the three fragment-size categories, but no significant temporal variation. Five 'common frugivores' provided sufficient data for detailed analyses. Spatially, we found significant variation in their densities, but no significant temporal variation. Overall, frugivore numbers did not appear to track fruit supplies across different fragments over time. These findings suggest that the distribution and movements of birds were most likely related to, and/or limited by, other factors such as nesting needs and fragmentation effects rather than fruit. The absence of long-distance resource tracking suggests a lack of long-distance dispersal, which implies (along with obvious ramifications for gene flow) minimal chances for recolonisation following local extinctions for tree species that depend on these birds for seed dispersal.     

Birds in the matrix: the role of agriculture in avian conservation in the Taita Hills,Kenya

Agricultural conversion of tropical forests is a major driver of biodiversity loss. Slowing rates of deforestation is a conservation priority, but it is also useful to consider how species diversity is retained across the agricultural matrix. Here, we assess how bird diversity varies in relation to land use in the Taita Hills, Kenya. We used point counts to survey birds along a land‐use gradient that included primary forest, secondary vegetation, agroforest, timber plantation and cropland. We found that the agricultural matrix supports an abundant and diverse bird community with high levels of species turnover, but that forest specialists are confined predominantly to primary forest, with the matrix dominated by forest visitors. Ordination analyses showed that representation of forest specialists decreases with distance from primary forest. With the exception of forest generalists, bird abundance and diversity are lowest in timber plantations. Contrary to expectation, we found feeding guilds at similar abundances in all land‐use types. We conclude that whilst the agricultural matrix, and agroforest in particular, makes a strong contribution to observed bird diversity at the landscape scale, intact primary forest is essential for maintaining this diversity, especially amongst species of conservation concern.     

Species richness and parasitism in an assemblage of parasitoids attacking maize stem borers in coastal Kenya

Abstract. 1. Parasitoids were reared from four species of lepidopteran stem borer collected in maize in southern coastal Kenya from 1992 to 1999. The stem borers included three native species, Sesamia calamistis Hampson, Busseola fusca Fuller, and Chilo orichalcociliellus (Strand), and one exotic borer, Chilo partellus (Swinhoe). A total of 174 663 caterpillars was collected, of which 12 645 were parasitised.
2. Twenty-six primary parasitoid species were reared from the exotic borer, C. partellus , indicating a rapid accumulation of native parasitoids on the alien borer.
3. The three most abundant parasitoids were the larval parasitoids Cotesia sesamiae Cameron, Cotesia flavipes (Cameron), and the pupal parasitoid Pediobius furvus Gahan. The pupal parasitoid Dentichasmias busseolae Heinrich and the larval parasitoid Goniozus indicus Ashmead were also common. All used an ingress-and-sting method of attack.
4. Cotesia flavipes , introduced into Kenya in 1993, was found in all seasons from 1997 onwards, and has become the most abundant stem borer larval parasitoid in the area. A native congener, Cotesia sesamiae , appeared in all seasons from 1992 to 1999. Together, these two parasitoids accounted for 83.3% of the parasitised borers.
5. Thirty parasitoid species were recovered in Kilifi district, 27 in Kwale, and 15 in Taita Taveta. Parasitism was much greater in Taita Taveta district than in Kilifi or Kwale districts.     

Gene flow in a direct-developing,leaf litter frog between isolated mountains in the Taita Hills,Kenya

Amphibians are in decline worldwide, and high altitude tropical areas appear to be the worst affected. This is in stark contrast with current information we have on gene flow in amphibian populations which focus on temperate pond breeding species. Using AFLP markers, we show that a small, direct-developing, leaf litter frog from the Taita Hills in south–west Kenya (Schoutedenella xenodactyloides) has extended populations covering large areas (>3.5 km) of fragmented, forest habitat, uncharacteristic of typical amphibian models. Further, we demonstrate high levels of gene flow (F _ST < 0.065) through unsuitable dry savannah habitat which might otherwise be considered a barrier to dispersal. Landscape genetic analysis demonstrates a strong link between hydrologic features, and further highlights links between sites through specific catchments. We propose a model of passive-active dispersal for the Dwarf Squeaker, S. xenodactyloides, which features passive downhill and active uphill movements over large areas, contrasting with limited cross slope movements. Our study highlights the importance of the diverse reproductive strategies of the Amphibia when considering dispersal and gene flow, and hence conservation management.     

Complementary seed dispersal by three avian frugivores in a fragmented Afromontane forest

Questions: To what extent does species‐specific variation in gut passage time (GPT), habitat use and mobility of three key avian frugivores synergistically affect the distribution of Xymalos monospora seeds within and among isolated forest fragments? Location: Three fragments of a severely fragmented cloud forest, Taita Hills, southeast Kenya. Methods: We experimentally determined GPTs of X. monospora seeds and recorded movements and habitat use by Turdus helleri, Andropadus milanjensis and Tauraco hartlaubi through radiotelemetry, and combined these data to generate species‐specific seed dispersal patterns. Results: Differences in mobility and habitat use among the three frugivores caused significant complementarity in seed dispersal, despite the fact that gut transit times were highly comparable. While the most sedentary and forest‐dependent species mainly led to short‐distance dispersal away from parent trees, two more mobile species dispersed seeds further away from the source trees, both within indigenous forest patches and towards exotic plantations and isolated fruiting trees in the landscape matrix. A. milanjensis inhabiting a very small forest fragment spent significantly more time in the landscape matrix than conspecifics residing in the two larger fragments. Conclusions: By varying distances over which seeds are carried away from parent trees and the habitat types in which they are ultimately deposited, avian frugivores affect the spatial distribution of seeds and early plant recruits in a distinct and complementary manner. Because landscape properties are expected to lead to different constraints on avian mobility for habitat specialists and for generalists, ecosystem processes such as avian seed dispersal are shaped by complex interactions between disperser behaviour and the environment.     

Potential tree species extinction,colonization and recruitment in Afromontane forest relicts

Tree species regeneration determines future forest structure and composition, but is often severely hampered in small forest relicts. To study succession, long-term field observations or simulation models are used but data, knowledge or resources to run such models are often scarce in tropical areas. We propose and implement a species accounting equation, which includes the co-occurring events extinction, colonization and recruitment and which can be solved by using data from a single inventory. We solved this species accounting equation for the 12 remaining Afromontane cloud forest relicts in Taita Hills, Kenya by comparing the tree species present among the seedling, sapling and mature tree layer in 82 plots. A simultaneous ordination of the seedling, sapling and mature tree layer data revealed that potential species extinctions, colonizations and recruitments may induce future species shifts. On landscape level, the potential extinction debt amounted to 9% (7 species) of the regional species pool. On forest relict level, the smallest relicts harbored an important proportion of the tree species diversity in the regeneration layer. The average potential recruitment credit, defined as species only present as seedling or sapling, was 3 and 6 species for large and small forest relicts, while the average potential extinction debt was 12 and 4 species, respectively. In total, both large and small relicts are expected to lose approximately 20% of their current local tree species pool. The species accounting equations provide a time and resource effective tool and give an improved understanding of the conservation status and possible future succession dynamics of forest relicts, which can be particularly useful in a context of participatory monitoring.     

De Brazza's monkeys (Cercopithecus neglectus) in Kenya: Census,distribution, and conservation

The population of De Brazza's monkeys (Cercopithecus neglectus) in Kenya, East Africa, was surveyed from May to September of 1983 to estimate its numbers, distribution, and conservation status. A small number of De Brazza's monkeys are protected within Saiwa National Park; however, the vast majority of the population is endangered because they are restricted to small, isolated pockets of forests amid expanding farmland within the Trans-Nzoia area of western Kenya. A few animals are found on the slopes of Mt. Elgon and on the Cherangani Hills, although these areas offer little protection. The pressures now facing this population are loss of habitat, reproductive isolation, and a decline in numbers as the result of being killed, either as a food source or as agricultural pests. If the current situation continues and no attempt is made to conserve the remaining De Brazza's monkeys, the species faces almost certain extinction in Kenya.