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Land-use change remains the main threat to tropical forests and their dependent fauna and flora, and degradation of existing forest remnants will further accelerate species loss. Forest degradation may result directly from human forest use or through spatial effects of land-use change. Understanding the drivers of forest degradation and its effects on biodiversity is pivotal for formulating impactful forest management and monitoring protocols, but such knowledge is lacking for many biodiversity hotspots, such as the Taita Hills in southeast Kenya. Here we first quantify effects of social factors (human activity and presence) at plot and landscape level, forest management (gazetted vs. non-gazetted) and spatial factors (fragment size and distance to forest edge) on the vegetation structure of indigenous Taita forest fragments. Next, we quantify effects of degraded vegetation structure on arthropod abundance and diversity. We show that human presence and activity at both the plot and landscape level explain variation in vegetation structure. We particularly provide evidence that despite a national ban on cutting of indigenous trees, poaching of pole-sized trees for subsistence use may be simplifying vegetation structure, with the strongest effects in edge-dominated, small forest fragments. Furthermore, we found support for a positive effect of vegetation structure on arthropod abundance, although the effect of daily maximum temperature and yearly variation was more pronounced. Maintenance of multi-layered forest vegetation in addition to reforestation maybe a key to conservation of the endangered and endemic fauna of the Taita Hills. [ABSTRACT FROM AUTHOR]

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. [ABSTRACT FROM AUTHOR]

Currently, there is an increasing need for evidence-based strategies in nature conservation, for example when designing and establishing nature reserves. In this contribution, we critically assess the ecological relevance of recent nature conservation practices in Kenya (East Africa), a region of global biodiversity hotspots. More specifically, we overlay the distribution of species richness (here based on mammals, birds, amphibians and vascular plants) with the location of nature reserves, the Kenyan agro-ecological zones (areas representing diverging agricultural potentials), and with the spatial distribution of human population density. Our analyses indicate that the majority of protected areas are located in areas with comparatively low species richness, while areas with extraordinary high levels of species richness are not adequately covered by nature reserves. Areas of high agricultural productivity (and with high human demographic pressure) are mainly reserved for high-yield agriculture; however, these regions are also characterised by high species richness. The majority of nature reserves are restricted to the semi-arid regions of Kenya, marginal for agricultural usage, but also with low levels of species richness. Based on this analysis, we prioritize areas for future protection. This single-country case illustrates that agricultural production in high-yield areas outweighs nature conservation goals, even in global biodiversity hotspot regions, and that priority setting may conflict with effective nature conservation. [ABSTRACT FROM AUTHOR]

Abstract: Using science knowledge to guide conservation action remains difficult; communication gaps persist, especially between scientists and other stakeholders including policy makers. Here, we demonstrate how we have managed to integrate scientific knowledge into consensually formulated conservation actions in the Taita Hills, Kenya. GIS-based least-cost modelling, together with sociological and forest characteristics were used to determine and prioritise the most appropriate areas for reforestation from a set of exotic forest plantations targeted for conversion into indigenous forests. This prioritisation was done through a succession of three workshops (on site) used to reach multiple stakeholders, build consensus on conservation actions, and formulate an implementation framework. Indigenous tree nurseries have now been established to provide planting stock for the reforestation activities agreed upon after the final workshop. The key lesson we learned from this exercise was that bridging the gap between science and conservation demands a very open, inter-disciplinary strategy, initiated and executed jointly by a diverse group of people that includes the Government (policy-makers and implementers), NGOs (conservationists and environmental advocates), scientists (researchers), conservationists and the local community. This study provides a pointer for what it may take to integrate human issues with sustained environmental management based on scientific knowledge. [Copyright &y& Elsevier]

Habitat fragmentation can restrict geneflow, reduce neighbourhood effective population size, and increase genetic drift and inbreeding in small, isolated habitat remnants. The extent to which habitat fragmentation leads to population fragmentation, however, differs among landscapes and taxa. Commonly, researchers use information on the current status of a species to predict population effects of habitat fragmentation. Such methods, however, do not convey information on species-specific responses to fragmentation. Here, we compare levels of past population differentiation, estimated from microsatellite genotypes, with contemporary dispersal rates, estimated from multi-strata capture-recapture models, to infer changes in mobility over time in seven sympatric, forest-dependent bird species of a Kenyan cloud forest archipelago. Overall, populations of sedentary species were more strongly differentiated and clustered compared to those of vagile ones, while geographical patterning suggested an important role of landscape structure in shaping genetic variation. However, five of seven species with broadly similar levels of genetic differentiation nevertheless differed substantially in their current dispersal rates. We conclude that post-fragmentation levels of vagility, without reference to past population connectivity, may not be the best predictor of how forest fragmentation affects the life history of forest-dependent species. As effective conservation strategies often hinge on accurate prediction of shifts in ecological and genetic relationships among populations, conservation practices based solely upon current population abundances or movements may, in the long term, prove to be inadequate. [ABSTRACT FROM AUTHOR]

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. [ABSTRACT FROM AUTHOR]

Abstract: We studied changes in area and species composition of six indigenous forest fragments in the Taita Hills, Kenya using 1955 and 1995 aerial photography with 2004 airborne digital camera mosaics. The study area is part of Eastern Arc Mountains, a global biodiversity hot spot that boasts an outstanding diversity of flora and fauna and a high level of endemism. While a total of 260ha (50%) of indigenous tropical cloud forest was lost to agriculture and bushland between 1955 and 2004, large-scale planting of exotic pines, eucalyptus, grevillea, black wattle and cypress on barren land during the same period resulted in a balanced total forest area. In the Taita Hills, like in other Afrotropical forests, indigenous forest loss may adversely affect ecosystem services. [Copyright &y& Elsevier]

Habitat attrition may affect ranging patterns of individuals in natural populations, e.g. by engendering larger territory sizes as the preferred habitat decreases. Radio-telemetry was used to explore the ranging behaviour of the white-starred robin Pogonocichla stellata in the highly fragmented Taita Hills landscape, south-east Kenya. Thirty-one males were radio-tracked in seven indigenous forest fragments differing in size and disturbance level. Although range size did not differ amongst patches, ranges overlapped more in the densely populated fragments. Using principal factor analysis, three principal factors corresponding to ‘openings’ (little foliage cover in all three strata), ‘proper forest’ (three-stratum forest) and ‘forest gaps’ (open upper canopy, dense understorey) were extracted. In all fragments, robins selected sparse to moderate foliage habitats, which best matched to the ‘proper forest’ factor, over open or very dense ones. Yet, the proportion of this preferred vegetation structure within home ranges differed across the forest fragments. Thus, lesser amounts of the selected habitat within the home ranges did not result in larger ranges. This could indicate high robin adaptability, surviving well with only nominal amounts of the preferred habitat within its home range. This is consistent with previous findings on this species based on fluctuating asymmetry and genetics. Résumé L'usure de l'habitat peut affecter les schémas de distribution des individus de populations naturelles, par exemple en générant des territoires de taille plus importante alors que l'habitat préféré diminue. La radio-télémétrie a servi à explorer le comportement de distribution du Rouge-gorge étoilé Pogonocichla stellata dans le paysage très fragmenté des Taita Hills, dans le sud-est du Kenya. On a suivi 31 mâles par radio-tracking dans sept fragments de forêt indigène dont la taille et le niveau de perturbation différaient. Bien que la taille des territoires n'ait pas été différente selon les îlots forestiers, ils se recouvraient davantage dans les îlots plus densément peuplés. En utilisant l'analyse de la composante principale, on a extrait trois facteurs principaux correspondant à des «éclaircies» (peu de couverture foliaire aux trois strates), à«la forêt proprement dite» (forêt à trois strates) et à des «trous dans la forêt» (canopée supérieure ouverte, sous-bois dense). Dans tous les fragments forestiers, les rouges-gorges sélectionnaient les habitats au feuillage rare à modéré, auxquels correspond le mieux la «forêt proprement dite», plutôt que les habitats très ouverts ou très denses. Ceci dit, la proportion de cette structure de végétation préférée au sein des territoires différait selon les fragments forestiers. Donc, une moins grande proportion de cet habitat sélectionné au sein des habitats n'avait pas pour résultat des territoires plus grands. Ceci pourrait indiquer la grande adaptabilité des rouges-gorges qui survivent bien même lorsque la superficie de l'habitat préféré dans leur territoire est minimale. Ceci correspond aux découvertes antérieures concernant cette espèce, basées sur la dissymétrie fluctuante et la génétique. [ABSTRACT FROM AUTHOR]

Sound knowledge of underlying mechanisms is essential for understanding how species respond to habitat fragmentation. Because most threatened species are typically the first ones to suffer local extinctions with forest fragmentation, studying why they fare poorly at the broader landscape scale is difficult. Related, sympatric but common species may be useful surrogates if they can provide insights germane for the conservation of rarer species. We illustrate this using a case study from the highly fragmented Taita Hills forests, south-eastern Kenya, of the Critically Endangered Taita thrush Turdus helleri and the more common white-starred robin Pogonocichla stellata as the surrogate. The responses of the thrush to habitat disturbance were in the same direction as the surrogate robin (e.g. higher fluctuating asymmetry, lower effective population densities and male-biased sex ratios), albeit they were detected sooner and were more severe because of its lower dispersal capacity. The key conservation measures proposed from the surrogate study largely matched those based on an independent evaluation of the thrush data. Additionally, the surrogate provided extra insights into the potential solutions for problems facing the thrush, and provided a base that could be used as a template for restoring the thrush populations in this area. Thus, our findings support the use of surrogate species in the conservation of sympatric related species in fragmented landscapes. We contend that this approach is also applicable for allopatric related species where landscapes are similar, provided that detailed data on population patterns and processes for the surrogate are available. [ABSTRACT FROM AUTHOR]

Montane grassland is a severely threatened habitat in Kenya. Despite a high level of faunal endemism, it has received very little conservation attention. We investigated habitat selection in a threatened grassland endemic bird species, Sharpe''s longclaw (Macronyx sharpei) (family Motacillidae), in order to understand its likely response to land-use changes. Between November 1995 and May 1996, we studied 41 territories of this species on the Kinangop Plateau in central Kenya. With an overall density of 0.4 birds ha−1, longclaws lived in permanent groups of two to seven individuals. They were sedentary and territorial, with a mean home range size of 0.5 ha. The species avoided non-grassland areas entirely, and within grassland showed a strong preference for short grass with tussocks. Territory sizes and foraging ranges were smaller, and rates of pecking for food higher, in this grassland type than in open short grass or long grass. Land use changes, in particular conversion to cultivation or woodlots and ploughing up of grassland to remove tussocks, pose a serious and immediate threat to this species. Dairy farming is potentially compatible with grassland conservation, and conservation-friendly livestock rearing needs to be promoted through economic incentives, awareness-raising and technical advice. [Copyright &y& Elsevier]

Aim We examined whether developmental instability can be used as a bio-monitoring tool in the endangered Taita thrush (Turdus helleri L.) through the measurement of individual levels of fluctuating asymmetry in tarsus length. Because estimates of the association between developmental instability, stress and fitness derived from traditional regression are biased, we compared parameter estimates obtained from likelihood based analysis with those obtained from a Bayesian latent variable model. Location Taita thrushes were captured and measured in three isolated cloud forest fragments located in the Taita Hills of south-east Kenya. Methods We applied mixed-effects regression with Restricted Maximum Likelihood parameter estimation (performed with SAS version 8.0) and Bayesian latent variable modelling (performed with WINBUGS version 1.3 and CODA version 0.4) to estimate unbiased levels of developmental instability and to model relationships between developmental instability and body condition in 312 Taita thrushes. Results Likelihood and Bayesian analyses yielded highly comparable results. Individual levels of developmental instability were strongly inversely related to body condition in the subpopulation with the lowest average condition. In contrast, both variables were unrelated in two other subpopulations with higher average condition. Such heterogeneity in association was in the direction expected by developmental theory, given that higher condition suggests more benign ambient conditions. The estimated levels of body condition in the three subpopulations did not support their presumed ranking in relation to environmental stress. Developmental instability and body condition are therefore believed to reflect different aspects of individual fitness. Main conclusions Variation in developmental homeostasis, either modelled as observable variable (fluctuating asymmetry) or latent variable (developmental instability), appears a useful indicator of stress effects in... [ABSTRACT FROM AUTHOR]

Dispersal affects both social behavior and population structure and is therefore a key determinant of long-term population persistence. However, dispersal strategies and responses to spatial habitat alteration may differ between sexes. Here we analyzed spatial and temporal variation in ten polymorphic microsatellite DNA loci of male and female Cabanis's greenbuls (Phyllastrephuscabanisi), a cooperative breeder of Afrotropical rainforest, to quantify rates of gene flow and fine-grained genetic structuring within and among fragmented populations. We found genetic evidence for female-biased dispersal at small spatial scales, but not at the landscape level. Local autocorrelation analysis provided evidence of positive genetic structure within 300 m distance ranges, which is consistent with behavioral observations of short-distance natal dispersal. At a landscape scale, individual-based autocorrelation values decreased over time while levels of admixture increased, possibly indicating increased gene flow over the past decade.

While fluctuating asymmetry (FA; small, random deviations from perfect symmetry in bilaterally symmetrical traits) is widely regarded as a proxy for environmental and genetic stress effects, empirical associations between FA and stress are often weak or heterogeneous among traits. A conceptually important source of heterogeneity in relationships with FA is variation in the selection history of the trait(s) under study, i.e. traits that experienced a (recent) history of directional change are predicted to be developmentally less stable, potentially through the loss of canalizing modifiers. Here we applied X-ray photography on museum specimens and live captures to test to what extent the magnitude of FA and FA-stress relationships covary with directional shifts in traits related to the flight apparatus of four East-African rainforest birds that underwent recent shifts in habitat quality and landscape connectivity. Both the magnitude and direction of phenotypic change varied among species, with some traits increasing in size while others decreased or maintained their original size. In three of the four species, traits that underwent larger directional changes were less strongly buffered against random perturbations during their development, and traits that increased in size over time developed more asymmetrically than those that decreased. As we believe that spurious relationships due to biased comparisons of historic (museum specimens) and current (field captures) samples can be ruled out, these results support the largely untested hypothesis that directional shifts may increase the sensitivity of developing traits to random perturbations of environmental or genetic origin.

We examined the effects of habitat fragmentation of the white-starred robin Pogonocichla stellata metapopulation in the Taita Hills archipelago, a hotspot for biodiversity which was fragmented approximately 40 years ago. Using seven microsatellite markers, we analysed the robin's genetic structure and tested for equilibrium between migration and drift (testing the probability of decreased dispersal) as well as between mutation and drift (test for recent reduction in effective population size, i.e. bottlenecks). This metapopulation was found to retain relatively high levels of genetic variability (H(E) between 0.63 and 0.71) and to be in migration-drift equilibrium, suggesting that increased isolation between fragments did not have much effect on the dispersal between them. Furthermore, this equilibrium test greatly enhanced the interpretation of parameters (e.g. F(ST)) assumed to have reached an equilibrium value. In contrast to previous findings on the related and sympatric Taita thrush Turdus helleri (which is critically endangered), there were no indications for recent bottlenecks in any of the robin subpopulations. This difference can be attributed to the higher dispersal capacity of the robin compared with the thrush (deduced from both the genetic and capture-recapture data). Our results stress the importance of sustained dispersal for species conservation.

What factors determine the persistence of species in fragmented habitats? To address this question, we studied the relative impacts of forest deterioration and fragmentation on bird species in 12 rainforest fragments in Kenya, combining 6 years of individual capture-recapture data with measurements of current captures and museum specimens. Species mobility, as estimated from species-specific dispersal rates, and tolerance to habitat deterioration, as estimated from change in fluctuating asymmetry with increasing habitat disturbance, explained 88% of the variation in patch occupancy among eight forest bird species. Occupancy increased with mobility and with tolerance to deterioration, where both variables contributed equally to this relationship. We conclude that individual-level study, such as of dispersal behavior and phenotypic development, can predict patterns of persistence at the species level. More generally, for conservation tactics to stand a high chance of success, they should include action both within sites, to minimize habitat deterioration, and across landscapes, to maximize dispersal.