Elevational gradients offer valuable opportunities to investigate biodiversity patterns and the ecological and evolutionary processes that shape them. Although tropical mountains are recognized as biodiversity hotspots, the various dimensions of biodiversity in these systems, particularly in equatorial Africa, remain poorly understood. In this study, we examined the functional (FD) and phylogenetic diversity (PD) of bird assemblages along a primary forest elevational gradient in Cameroon, West-Central Africa, spanning from lowland forests to the treeline (~2300 m a.s.l.). We analyzed how FD and PD vary with elevation and tested the roles of abiotic filtering and biotic interactions, such as competition, in community assembly. Additionally, we assessed whether taxonomic diversity (TD) increases through niche packing or expansion, based on morphological and resource-use traits. Using null models and bird occurrence data, we inferred the drivers of FD and PD patterns and evaluated whether species in more diverse assemblages occupied novel functional space compared to less diverse assemblages. Our results showed that both functional richness and TD declined with elevation, whereas functional nearest neighbor distance, functional evenness, and mean nearest taxon distance increased. Traits related to resource use suggested that bird species at higher elevations were functionally less similar than expected by chance, partially supporting the influence of competition consistent with the guild assembly rule. Phylogenetic clustering observed at both low and high elevations pointed to independent species radiations, likely shaped by historical forest dynamics. In species-rich lowland assemblages, we found evidence of niche packing, suggesting increased specialization or niche overlap. In contrast, niche expansion appeared to contribute to higher TD at elevated sites. Overall, our findings indicate that while abiotic filters along forested elevational gradients and competition in lowland forests play roles in shaping avian diversity, they are not the sole or dominant mechanisms. Nonetheless, partial support for competition aligns with theoretical expectations under the guild assembly framework.

Two distinct diversity patterns are observed along tropical elevations: (a) decreasing number of species toward high elevations and (b) a hump-shaped pattern with the peak at mid-elevations. As diversity is likely supported by ecological capacity of the environment, decomposition of the overall richness into ecological facets and considering number of individuals within them is crucial for the proper understanding of richness patterns. We examined abundances of different avian guilds along the forested part of the elevational gradient on Mt. Cameroon. We (a) compared richness and abundance elevational patterns, (b) assessed the effective contribution of multiple guilds to richness and abundance patterns, and (c) assessed to what extent observed abundances of guilds differed from those expected by chance. We sampled birds in 2011-2015 during the dry season at seven elevations (30 m, 350 m, 650 m, 1100 m, 1500 m, 1850 m, 2200 m a.s.l.). For each assemblage, we estimated proportions of species and individuals that use particular diets, foraging modes, and feeding strata. We found that a rather decreasing pattern of species richness turns into a hump-shaped one if we look at the total abundances, implying different mechanisms behind these patterns. The number of species and individuals thus do not seem to be directly related, contrary to "the more-individuals hypothesis." Abundances of foliage gleaners at mid-elevations, nectarivores at high elevations, and frugivores at low elevations deviated from random expectations. Our results imply that parts of ecological space are filled separately by bird species and individuals along elevation of Mt. Cameroon.

To test if tree species richness and forest structure drive spatial variation in avian communities along a tropical elevation gradient and to present information about the role of detailed forest parameters.

The probability of occurrence of bird species in towns/cities increases with their range sizes, and Rapoport’s rule states that range sizes increase with latitude. To test the hypothesis that the increasing number of bird species persisting in cities at higher latitudes of Europe is linked to their larger range sizes, we compiled data on bird communities of: a) 41 urban bird atlases; b) 37 city core zones from published sources; c) regions of nine grid cells of the EBCC Atlas of European Breeding Birds around each city. We tested whether the proportion of species from particular regional bird assemblages entering cities (i.e., proportional richness) was related to the geographical position, mean range size of regional avifaunas, proportion of vegetated areas and city habitat heterogeneity. The mean range sizes of the observed and randomly selected urban avifaunas were contrasted. The proportional richness of urban avifaunas was positively related to the geographic position and mean range size of birds in regional assemblages. The evidence favoured range sizes if considering the European range sizes or latitudinal extents, but was limited for global range sizes. Randomizations tended to show larger range sizes for the real avifaunas than in the randomly selected ones. For urban core zones, the results were less clear-cut with some evidence only in favour of the European range sizes. No role of vegetation or habitat heterogeneity was found. In conclusion, while vegetation availability or heterogeneity did not show any effects, spatial position and range sizes of birds in regional assemblages seemed to influence the proportional richness of cities and their core zones. Factors correlated with spatial position (e.g., climate) might increase the attractivity of particular cities to birds. However, the effects of range sizes indicated that urbanization possibly has more negative impacts on the avifauna in the regions occupied by less widespread species.

Recent observations from the tropics indicate seasonal peaks in breeding and vocal activity of some bird species. However, information about seasonality in vocal activity at the community level is still lacking in the tropics. We examined seasonal variation in the diurnal vocal activity of lowland rain forest birds on Mount Cameroon, using weekly automatic sound recording throughout the whole year and related it to rainfall and temperature. We show that the bird community in lowland rain forest vocalized year-round, but species richness as well as the vocal activity of the community varied greatly during the year. This variation coincided with the seasonality of rainfall. The highest number of species (31.5 on average) sang at the beginning of the driest period, followed by a gradual decrease in singing with increasing rainfall (minimum 14.5 species). This indicates that intensive rainfall indirectly limits the vocal activity of the tropical rain-forest bird community. Temporal turnover of vocalizing species as well as within-day variation in vocal activity was highest during the transition period between dry and rainy seasons. We suggest that this could reflect differing timing in the breeding activity of particular feeding guilds to follow seasonal peaks of their diets.

African Journal of EcologyVolume 56, Issue 3 p. 679-683 SHORT COMMUNICATION Something is missing at the bottom: Importance of coastal rainforests for conservation of trees, birds and butterflies in the Mount Cameroon area Michal Ferenc, Corresponding Author Michal Ferenc ferenc.michal85@gmail.com orcid.org/0000-0002-6730-7272 Department of Ecology, Faculty of Science, Charles University, Praha 2, Czechia Correspondence Michal Ferenc Email: ferenc.michal85@gmail.comSearch for more papers by this authorOndřej Sedláček, Ondřej Sedláček Department of Ecology, Faculty of Science, Charles University, Praha 2, CzechiaSearch for more papers by this authorRobert Tropek, Robert Tropek Department of Ecology, Faculty of Science, Charles University, Praha 2, Czechia Institute of Entomology, Biology Centre, Czech Academy of Sciences, České Budějovice, CzechiaSearch for more papers by this authorTomáš Albrecht, Tomáš Albrecht Department of Zoology, Faculty of Science, Charles University, Praha 2, Czechia Institute of Vertebrate Biology, Czech Academy of Sciences, Brno, CzechiaSearch for more papers by this authorJan Altman, Jan Altman Institute of Botany, Czech Academy of Sciences, Průhonice, CzechiaSearch for more papers by this authorMartin Dančák, Martin Dančák Department of Ecology and Environmental Sciences, Faculty of Science, Palacký University, Olomouc, CzechiaSearch for more papers by this authorJiří Doležal, Jiří Doležal Institute of Botany, Czech Academy of Sciences, Průhonice, Czechia Faculty of Science, University of South Bohemia, České Budějovice, CzechiaSearch for more papers by this authorŠtěpán Janeček, Štěpán Janeček Department of Ecology, Faculty of Science, Charles University, Praha 2, Czechia Institute of Botany, Czech Academy of Sciences, Průhonice, CzechiaSearch for more papers by this authorVincent Maicher, Vincent Maicher Institute of Entomology, Biology Centre, Czech Academy of Sciences, České Budějovice, Czechia Faculty of Science, University of South Bohemia, České Budějovice, CzechiaSearch for more papers by this authorĽuboš Majeský, Ľuboš Majeský Department of Botany, Faculty of Science, Palacký University, Olomouc, CzechiaSearch for more papers by this authorFrancis N. Motombi, Francis N. Motombi Botanic Garden, Limbe, Cameroon The Congo Basin Institute, Yaoundé, CameroonSearch for more papers by this authorMercy Murkwe, Mercy Murkwe Department of Ecology, Faculty of Science, Charles University, Praha 2, Czechia Department of Zoology and Animal Physiology, Faculty of Science, University of Buea, Buea, CameroonSearch for more papers by this authorSzabolcs Sáfián, Szabolcs Sáfián Faculty of Science, University of South Bohemia, České Budějovice, CzechiaSearch for more papers by this authorMiroslav Svoboda, Miroslav Svoboda Faculty of Forestry and Wood Sciences, Czech University of Life Sciences, Praha 6, CzechiaSearch for more papers by this authorDavid Hořák, David Hořák Department of Ecology, Faculty of Science, Charles University, Praha 2, CzechiaSearch for more papers by this author Michal Ferenc, Corresponding Author Michal Ferenc ferenc.michal85@gmail.com orcid.org/0000-0002-6730-7272 Department of Ecology, Faculty of Science, Charles University, Praha 2, Czechia Correspondence Michal Ferenc Email: ferenc.michal85@gmail.comSearch for more papers by this authorOndřej Sedláček, Ondřej Sedláček Department of Ecology, Faculty of Science, Charles University, Praha 2, CzechiaSearch for more papers by this authorRobert Tropek, Robert Tropek Department of Ecology, Faculty of Science, Charles University, Praha 2, Czechia Institute of Entomology, Biology Centre, Czech Academy of Sciences, České Budějovice, CzechiaSearch for more papers by this authorTomáš Albrecht, Tomáš Albrecht Department of Zoology, Faculty of Science, Charles University, Praha 2, Czechia Institute of Vertebrate Biology, Czech Academy of Sciences, Brno, CzechiaSearch for more papers by this authorJan Altman, Jan Altman Institute of Botany, Czech Academy of Sciences, Průhonice, CzechiaSearch for more papers by this authorMartin Dančák, Martin Dančák Department of Ecology and Environmental Sciences, Faculty of Science, Palacký University, Olomouc, CzechiaSearch for more papers by this authorJiří Doležal, Jiří Doležal Institute of Botany, Czech Academy of Sciences, Průhonice, Czechia Faculty of Science, University of South Bohemia, České Budějovice, CzechiaSearch for more papers by this authorŠtěpán Janeček, Štěpán Janeček Department of Ecology, Faculty of Science, Charles University, Praha 2, Czechia Institute of Botany, Czech Academy of Sciences, Průhonice, CzechiaSearch for more papers by this authorVincent Maicher, Vincent Maicher Institute of Entomology, Biology Centre, Czech Academy of Sciences, České Budějovice, Czechia Faculty of Science, University of South Bohemia, České Budějovice, CzechiaSearch for more papers by this authorĽuboš Majeský, Ľuboš Majeský Department of Botany, Faculty of Science, Palacký University, Olomouc, CzechiaSearch for more papers by this authorFrancis N. Motombi, Francis N. Motombi Botanic Garden, Limbe, Cameroon The Congo Basin Institute, Yaoundé, CameroonSearch for more papers by this authorMercy Murkwe, Mercy Murkwe Department of Ecology, Faculty of Science, Charles University, Praha 2, Czechia Department of Zoology and Animal Physiology, Faculty of Science, University of Buea, Buea, CameroonSearch for more papers by this authorSzabolcs Sáfián, Szabolcs Sáfián Faculty of Science, University of South Bohemia, České Budějovice, CzechiaSearch for more papers by this authorMiroslav Svoboda, Miroslav Svoboda Faculty of Forestry and Wood Sciences, Czech University of Life Sciences, Praha 6, CzechiaSearch for more papers by this authorDavid Hořák, David Hořák Department of Ecology, Faculty of Science, Charles University, Praha 2, CzechiaSearch for more papers by this author First published: 16 February 2018 https://doi.org/10.1111/aje.12506Citations: 8Read the full textAboutPDF ToolsRequest permissionExport citationAdd to favoritesTrack citation ShareShare Give accessShare full text accessShare full-text accessPlease review our Terms and Conditions of Use and check box below to share full-text version of article.I have read and accept the Wiley Online Library Terms and Conditions of UseShareable LinkUse the link below to share a full-text version of this article with your friends and colleagues. Learn more.Copy URL Share a linkShare onFacebookTwitterLinkedInRedditWechat CONFLICT OF INTEREST The authors declare that they have no conflict of interest. Citing Literature Volume56, Issue3September 2018Pages 679-683 RelatedInformation

Urban bird communities are homogenized across large spatial scales, suggesting that the urban environment acts as an environmental filter. We hypothesize that large scale commonness is a better predictor of urban affinity of birds than any particular species trait. We estimated the relative importance of taxonomy, reproductive, ecological and morphological traits, and commonness of individual bird species. We compiled data on i) breeding bird communities of 41 European cities from urban bird atlases, and ii) regional bird assemblages defined by nine grid cells of the Atlas of European Breeding Bird around each city, and quantified the urban affinity of each species by comparing its incidence in cities and in randomly drawn communities from respective regional assemblages. Conditional inference tree-based random forest analysis was utilized to assess the importance of individual predictors. A sign test was used to detect differences between congeneric pairs of species with contrasting affinity to cities. Birds associated with woody habitats and those having altricial chicks had higher affinity for cities. Of the other reproductive traits, only clutch size showed an association with urban affinity. Different bird orders differed significantly in their urban affinity, exemplifying the homogenizing effect of cities. However, by far the most important factor associated with bird tolerance to the urban environment was species commonness, indicating that either the traits associated with commonness, or population effects driven by commonness, are responsible for their presence in cities.

The prominent role of the absolute amount of (semi)natural habitats on urban avifauna richness is well documented; however the relative role of habitat availability, heterogeneity and spatial position at the scale of a whole city has not been investigated so far. The main objective of this study was to evaluate the relative influence of these variables on the species richness and rarity value of bird communities in the city of Prague, Czech Republic. We used three modes to describe the urban environment, resulting in different habitat category resolutions. Coarse habitat descriptors were good enough for predicting species richness, but a more detailed resolution was better in explaining the distribution of communities comprising rarer species. The availability of wooded habitats was consistently the most important variable explaining both richness and rarity of bird communities. Habitat heterogeneity enhanced species richness, especially in highly urbanized areas where wooded habitats were scarce. However, rarer species responded to habitat heterogeneity only weakly. The influence of grid cell spatial position on bird community richness was overridden by the impacts of habitat availability and heterogeneity. However, communities comprising rarer species tended to breed at peripheral sites encompassing open habitats and large woodlands. The preservation of sufficient wooded habitats including small patches remains the key tool for bird conservation in cities, and habitat heterogeneity should be supported in areas with less than ca. 3 % of wooded habitats. Rarer species benefit from the maintenance of more extensive patches of greenery in peripheral urban areas.

The usual positive inter-specific relationship between range size and abundance of local populations can have notable exceptions in Afrotropical montane areas, where range-restricted bird species are unusually abundant. We tested how the area occupied locally by passerines and their geographic range size relate to local abundances along a tropical elevational gradient of Mt Cameroon, West-Central Africa. Data on bird assemblages were collected at six forested elevations (350, 650, 1100, 1500, 1850 m, 2200 m a.s.l.) using a standardised point count at 16 locations per elevation. Elevational ranges of birds were compiled from published sources and their geographic range sizes were determined as the occupancy of 1° x 1° grid cells. The observed relationship between local abundance and geographic range size within the entire passerine assemblage on Mt Cameroon disagrees with the most frequently reported positive pattern. However, the patterns differ among elevations, with positive trends of the abundance-range size relationship in lowland changing to negative trends towards higher elevations. Interestingly, the total assemblage abundances do not differ much among elevations and population size estimates of species occupying different parts of the gradient remain relatively constant. These patterns are caused by relatively high abundances of montane species, which might be a result of long-term ecological specialization and/or competitive release in species-poor montane locations and possibly facilitated by an extinction filter. Our data suggest that montane species’ abilities to maintain dense populations might compensate for less area available near mountain tops and help these populations to circumvent extinction.

Acoustic signals are frequently used for estimating avian species richness, abundance and community composition. However, sampling by traditional methods of bird surveys is often limited by availability of experienced researchers in the field, especially in the tropics. New bioacoustic approaches offer some solutions to such limitations and provide opportunities for more extensive spatial and temporal sampling. In our study, we compared results of traditional point counts with simultaneous acoustic samples obtained by automated soundscape recording units in the montane forest of Mount Cameroon. We showed that the estimates of species richness, abundance and community composition based on point counts and post-hoc laboratory listening to acoustic samples are very similar, especially for a distance limited up to 50m. Species that were frequently missed during both point counts and listening to acoustic samples were typically those with relatively quiet songs. Abundances were rather underestimated by listening to acoustic samples in the most abundant species, including those occurring in flocks and species with low singing activity. Despite some possible biases, we demonstrated that the method based on listening to acoustic samples is relatively effective and offers a useful alternative approach for surveying Afromontane bird communities.

Wooded habitats represent hotspots of urban biodiversity, however, urban development imposes pressure on biota in these refuges. Identification of the most influential habitat attributes and the role of local urban characteristics is crucial for proper decisions on management practices supporting biodiversity. We aimed to identify well manageable fine-scale habitat attributes to suggest specific, feasible and affordable management recommendations for green space in cities. We analysed species richness of woodland-associated bird communities and incidence of individual species at 290 sites in a wide variety of green areas scattered across the city of Prague, Czech Republic. Generalized linear mixed models (GLMM) and regression tree analyses were used to identify site-scale (100 m radius sampling sites) and local-scale (200 m and 500 m radius plots) habitat attributes shaping the bird communities at individual sites. Logistic regression was used to assess the responses of individual species to habitat characteristics. Our results imply that at the site scale, management practices should focus on maintenance and promoting species-diverse and older tree stands, with a mixture of coniferous and deciduous trees. Water-bodies and accompanying riparian habitats should be maintained and carefully managed to preserve high-quality remnants of natural vegetation. Presence of a few old trees (about 12 % of tree cover with DBH > 50 cm) or small urban standing water and watercourses enrich the bird community by at least two species. Species richness of woodland avifauna at particular sites is further supported by the total amount of tree cover in the surroundings, including scattered greenery of public spaces and private gardens. We conclude that proper management at site scale has the potential to increase biodiversity of the urban environment.

Aim To compare macroecological patterns between bird communities of European cities and regional species assemblages in the surrounding landscape, and to reveal geographical trends in the urbanization of native avifauna. Location Forty-one towns and cities in continental Europe. Methods We compiled data on the species richness and community composition of urban avifauna from 41 European city breeding bird atlases, and of species assemblages comprising nine grid cells (each about 50 km x 50 km) from the EBCC Atlas of European Breeding Birds (hereafter regional assemblages). Species-area relationships (SARs), latitudinal trends in diversity and the distance decay of community similarity were compared using regression models (generalized linear models). Observed urban communities were compared with randomly assembled ones to reveal systematic effects of the urban environment on native bird communities across Europe. We employed variance partitioning to quantify the relative effect of environmental parameters and the spatial position of cities on species richness. Results The species-area relationships did not differ significantly between cities and regional assemblages. Species richness of both types of communities increased towards higher latitudes, although the relationship was unimodal for regional assemblages, in contrast to cities. The increase in beta diversity with distance was on average less pronounced in cities than in regional assemblages, and was lower between individual cities than between communities of the same size randomly drawn from regional species assemblages. Moreover, average beta diversity was lower in northern cities, which are characterized by a relatively higher proportion of species from regional species pools. Main conclusions The species-area relationship and latitudinal trends are largely congruent between cities and the regional assemblages. However, city avifaunas tend to be relatively more uniform across space, revealing biotic homogenization. Urban communities in northern cities are more uniform as a higher proportion of bird species breeds in cities.

The western mountain greenbul, Andropadus tephrolaemus, is a poorly-known monomorphic forest greenbul. We investigated whether morphological measurements could be used to discriminate between sexes of this species, with a sample of birds captured in two forest types on Mt Cameroon. We used discriminant function analysis based on a combination of traits to develop models to discriminate between sexes. The sex of birds predicted from these models was compared with molecular sexing of the same individuals. Discriminant analysis revealed that a discriminant function incorporating wing length, tail length and bill height allowed 74% of western mountain greenbuls to be sexed correctly based on morphometric measurements alone. Sex ratios varied between montane and lowland forests, with the former having a higher proportion of males (70.5 and 54.6%, respectively), but the difference was not statistically significant. Cloacal sizes did not differ between males and females, and males do not develop large cloacal protuberances while breeding. This is in agreement with low predicted levels of sperm competition in this species. We show that sexing based on morphology has its limitations, but can still provide some insight if DNA analysis is not available.

The Cameroon volcanic line montane forests host specific avian assemblages with many endemic species. Such unique bird assemblages deserve adequate description for proper protection. For this purpose, we sampled birds in the upper montane forests of Mts Cameroon and Oku situated at ~2,250 m. We combined point counts and continuous observations to describe species composition and estimate densities of particular species. In total, we recorded 106 species; 45 only on Mt Oku, 21 only on Mt Cameroon, and 40 common to both mountains. The higher species richness on Mt Oku was due to non-forest species that invade the forest interior due to recent human disturbance. Endemic species of the Cameroon volcanic line and montane non-endemic species had higher abundances than widespread species in general. As a result, we did not find a positive abundance–range-size relationship for both locations. Our findings support a previously made observation that montane species of the Cameroon volcanic line have higher densities compared to widespread species. However, we also show that the structures of avian assemblages vary between sites as species spatial turnover was lower on Mt Cameroon than on Mt Oku and species common to both were more abundant on Mt Cameroon. This could be attributed to the more pristine forest on Mt Cameroon, with higher annual rainfall but also due to lower human impact and the existence of a continuous forest. Conservation action within the broader landscape context is thus necessary to secure diverse montane forests in West-Central Africa in the future.

Geographic variation in avian clutch size is thought to be related to the variation in nest predation rate and food availability. We studied predation on artificial ground nests along a large-scale geographic gradient in South Africa characterised by increasing productivity from the deserts in the west to humid savannas in the east, and calculated mean clutch sizes of birds occurring in atlas quadrates surrounding our study sites. Clutch sizes generally increased with increasing productivity and seasonality. The least productive desert site was characterised also by the highest predation rate, whereas all the other sites located in savannas revealed much lower and more or less constant predation rate. We found no evidence for relationship between nest predation rates and clutch sizes of ground-nesting birds. This indicates that food availability is the major factor responsible for geographical variation in bird clutch sizes across South Africa, though high predation rate might also contribute to low clutch size in least productive arid environments.