Effects of site and fruit size on the composition of avian frugivore assemblages in a fragmented Afrotropical forest

Factors influencing the interaction between fruiting trees and their frugivorous seed dispersers in fragmented Afrotropical landscapes are poorly known. With the use of Mantel statistics we analysed assemblages of frugivorous birds on 58 individual trees belonging to 11 species growing in seven Kenyan cloud forest fragments. Overall, frugivores showed little specialization on particular trees. Fruit size explained a substantial amount of the variation in frugivore assemblages among different tree species at the same site. In addition, frugivore assemblages on conspecific trees were significantly more similar when the trees occurred at the same site. This location effect was attributable to the different sites and forest fragments (of different sizes and disturbance levels) varying in the densities and composition of their avian frugivores, vegetation composition and tree fruiting phenologies. It was consolidated further by the low mobility of most of these avian frugivores, particularly their reluctance to cross between forest fragments. Habitat disturbance and fragmentation may therefore have affected fruit selection, with implications for both seed dispersal and regeneration.     

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.     

Use of Fruiting Trees by Birds in Continuous Forest and Riparian Forest Remnants in Los Tuxtlas,Veracruz, Mexico1

The composition of plant species in fragmented landscapes may be influenced by the pattern of visitation by birds to fruiting trees and by the movement of seeds among and within fragments. We compared bird visitation patterns to two tree species (Dendropanax arboreus, Araliaceae; Bursera simaruba, Burseraceae) in continuous forest and remnants of riparian vegetation in a region dominated by pasture in Los Tuxtlas, Veracruz, Mexico. We quantified frequency of visitation, fruit consumption, consistency of visitation (percentage of total tree observation periods during which a given bird species was recorded), and species composition of birds at individuals of both tree species in continuous forest and riparian remnants. Bird visitation rate, species richness, and fruit consumption rates were similar within both tree species in the two habitats. Species assemblages at D. arboreus were different between continuous forest and remnants. Species assemblages at B. simaruba did not differ by habitat. Our results demonstrate that habitat disturbance may influence avian visitation patterns, which may in turn affect subsequent recruitment patterns in some tree species. Our results, however, were not consistent between the tree species, suggesting that it is difficult to generalize concerning the effects of forest disturbance on avian species assemblages in fruiting trees.     

Diversity of seeds captured by interception exceeds diversity of seeds deposited in traps

Seed dispersal, a key process in terrestrial landscapes, is increasingly important in the face of habitat fragmentation and global climate change. Seed dispersal is also notoriously difficult to characterize, especially in species rich and spatially complex tropical forests. We contrasted assemblages of biotically dispersed seeds collected from four sites using two methods: deposition into seed traps and interception by the capture of frugivorous birds. We also compared seed deposition and interception with local fruit production. Species accumulation curves for seeds deposited in seed traps began to level off sooner than curves for seeds collected from birds captured in mist nets, and extrapolation showed significantly greater estimated species richness for seeds collected from birds than for those deposited in traps. Assemblages from birds and from traps at each site were quite different, with an abundance‐based similarity index of 0.64; this dissimilarity increases if bat‐dispersed seeds are included in the analysis. Common bird‐dispersed species were retrieved from both mist‐netted birds and from seed traps, but numerous locally fruiting understory species were recovered only from birds. We conclude that the sampling of seeds carried by birds provides a valuable complement to other methods of studying seed dispersal in species‐rich tropical forests by revealing relationships between specific dispersers and their seed plants and by creating a more complete account of species diversity of seeds being transported at a given site.     

The role of farm structure on bird assemblages around a Kenyan tropical rainforest

Although it is clear that the farmlands neighbouring fragmented forests are utilized by some forest birds, it is not clear how birds in general respond to farmland habitat mosaic. An effort was made to determine how bird density and foraging assemblages were influenced by farm structural characteristics and distance from forest edge. Thirty farms up to a distance of 12 km around Kakamega forest in western Kenya were studied. Farm structure entailed size, hedge volume, habitat heterogeneity, woody plant density, plant diversity and crop cover. Birds were surveyed using line transects and DISTANCE analyses and classified into six feeding guilds and three habitat associations. Size of farms increased away from the forest, as woody plant density, plant diversity, indigenous trees and subsistence crop cover declined. The most important farm structure variable was hedge volume, which enhanced bird species richness, richness of shrub‐land bird species and insectivorous bird density (R = 0.58, P < 0.01). Bird density increased with tree density while indigenous trees were suitable for insectivores and nectarivores. There were very few forest bird encounters. Agricultural practices incorporating maintenance of hedges and sound selection of agroforestry trees can enhance conservation of birds on farmland, though, not significantly for forest species.     

Frugivory,Post‐feeding Flights of Frugivorous Birds and the Movement of Seeds in a Brazilian Fragmented Landscape

Habitat fragmentation can break down the movement processes of frugivorous animals, thus influencing the relationship between plants and their seed dispersers by altering the number and identity of seed dispersers, and their relative contribution to seed dispersal. We studied the assemblages of frugivorous birds, their composition, species richness, and visitation rates to fruiting plants growing in the different landscape elements (forest fragments, live fences, and trees isolated in pastures) embedded in a Brazilian fragmented, agricultural landscape. By following the post‐feeding movements of frugivorous birds, we inferred the direction of seed movement from and to each of these landscape elements. Fruiting trees growing at different landscape elements were visited by frugivorous birds at similar rates. Isolated trees attracted a greater and distinct bird assemblage than trees in forest fragments or live fences. Judging by the post‐feeding flights of birds, the seeds of isolated trees were the most likely to reach all the landscape elements considered, but the contribution of isolated trees to the seeds falling in forested habitats or pastures depended on their degree of isolation. A few bird species were able to move widely, visiting fruiting plants in all landscape elements, and promoting long‐distance dispersal for plants. These few birds are of special interest because they are mobile links that connect habitats in fragmented landscapes with their seed dispersal services. Abstract in Spanish is available at http://www.blackwell‐synergy.com/loi/btp .     

The timing of frugivore‐mediated seed dispersal effectiveness

The seed dispersal effectiveness framework allows assessing mutualistic services from frugivorous animals in terms of quantity and quality. Quantity accounts for the number of seeds dispersed and quality for the probability of recruitment of dispersed seeds. Research on this topic has largely focused on the spatial patterns of seed deposition because seed fates often vary between microhabitats due to differences in biotic and abiotic factors. However, the temporal dimension has remained completely overlooked despite these factors—and even local disperser assemblages—can change dramatically during long fruiting periods. Here, we test timing effects on seed dispersal effectiveness, using as study case a keystone shrub species dispersed by frugivorous birds and with a fruiting period of 9 months. We evaluated quantity and quality in different microhabitats of a Mediterranean forest and different periods of the fruiting phenophase. We identified the bird species responsible for seed deposition through DNA barcoding and evaluated the probability of seedling recruitment through a series of field experiments on sequential demographic processes. We found that timing matters: The disperser assemblage was temporally structured, seed viability decreased markedly during the plant's fruiting phenophase, and germination was lower for viable seeds dispersed in the fruiting peak. We show how small contributions to seed deposition by transient migratory species can result in a relevant effectiveness if they disperse seeds in a high‐quality period for seedling recruitment. This study expands our understanding of seed dispersal effectiveness, highlighting the importance of timing and infrequent interactions for population and community dynamics.     

The Amazon River as a dispersal barrier to passerine birds: effects of river width, habitat and taxonomy

Aim To evaluate the relative effectiveness of the lower and upper sections, respectively, of the Amazon River as a barrier to bird distribution, and to evaluate ecological and taxonomic factors affecting the efficacy of the river barrier. Location Amazon River of South America between its confluence with the Napo River in the west and its delta in the east. Methods Using published distribution maps for 448 species of passerine birds occurring along the Amazon River, we evaluated whether each was distributed along one bank only (river presumed to be a barrier) or both banks (no barrier) to test the predictions that the river was more effective as a dispersal barrier: (1) along the lower, wider portion of the river than the upper, narrower portion; (2) for species inhabiting forests than open country; (3) for species inhabiting forest understorey than forest canopy; (4) for species restricted to terra firme (never inundated upland forest) than those not restricted to terra firme and (5) for certain taxonomic groups. Results Our analyses demonstrated that the Amazon River was most effective as a dispersal barrier along its lower portion and for species restricted to forests and terra firme. However, the river was not significantly more of a barrier for species inhabiting forest understorey than forest canopy. The river was most significant as a barrier to dispersal for the antbirds (Thamnophilidae) and was less significant as a barrier to species belonging to several large families including woodcreepers (Dendrocolaptidae), ovenbirds (Furnariidae), flycatchers (Tyrannidae), cotingids (Cotingidae), tanagers (Thraupidae), seed‐eating finches (Emberizidae) and blackbirds (Icteridae). Main conclusions The robust widths of Amazonian rivers are widely considered to represent impediments to dispersal and gene flow for many taxa of birds and other animals, and may have represented agents of vicariance in the diversification of species. Our study reaffirms the effectiveness of the lower Amazon River as a current barrier to bird dispersal for forest birds and provides new insights into the effects of habitat and taxonomy on the efficacy of the river barrier. Although supportive of several predictions of the river hypothesis of biological diversification, our study is limited in addressing the historical impact of river barriers as agents of vicariance in the process of diversification.     

Avian Habitat Preference in Tropical Forest Restoration in Southern Costa Rica

An important question for tropical forest restoration is whether degraded lands can be actively managed to attract birds. We censused birds and measured vegetation structure at 27 stations in young (6–9‐yr old) actively and passively restored pasture and old growth forest at Las Cruces Biological Station in southern Costa Rica. During 481 10‐min point counts, we detected a high diversity—186 species—of birds using the restoration area. Surprisingly, species richness and detection frequency did not differ among habitats, and proportional similarity of bird assemblages to old growth forest did not differ between restoration treatments. Bird detection frequency was instead explained by exotic grass cover and understory stem density—vegetation structures that were not strongly impacted by active restoration. The similarity of bird assemblages in actively and passively restored forest may be attributed to differential habitat preferences within and among feeding guilds, low structural contrast between treatments, or the effect of nucleation from actively restored plots into passively restored areas. Rapid recovery of vegetation in this recently restored site is likely due to its proximity to old growth forest and the lack of barriers to effective seed dispersal. Previous restoration studies in highly binary environments (i.e., open pasture vs. tree plantation) have found strong differences in bird abundance and richness. Our data contradict this trend, and suggest that tropical restoration ecologists should carefully consider: (1) when the benefits of active restoration outweigh the cost of implementation; and (2) which avian guilds should be used to measure restoration success given differential responses to habitat structure.     

Seed dispersal by changing frugivore assemblages: a mechanistic test of global change effects

In the face of global change it is important to understand how changes in species abundance and richness can affect ecosystem functions. Here we modelled seed dispersal by animals in a fragmented secondary forest of the Cantabrian Range (northwestern Iberian Peninsula), simulating the activity of six frugivorous bird species when dispersing three species of fleshy‐fruited trees. We calculated the density and richness of seeds deposited across a forested landscape, as well as the density of seeds arriving to open areas. We 1) study the complementarity of functional traits of each species with frugivore assemblages varying in species compositions (i.e. abundance and richness of bird assemblages), 2) identify those bird species whose functional roles are not redundant, and 3) explore the response of seed dispersal to random losses and to two non‐random bird loss scenarios (i.e. overhunting and fewer individuals from migrant species). We found that simulations with the avian composition observed in the field (i.e. with uneven abundances of six bird species) led to values of seed dispersal higher to those emerging from four bird species equally abundant. The selective removal of dominant bird species led to significant decays in seed dispersal, suggesting non‐redundant roles of abundant bird species. Seed dispersal decays were stronger under non‐random than random scenarios of bird loss. In terms of seed density, the functional decays also differed between the scenarios of overhunting and reduced arrival of migrant birds, notably beyond 50% changes in bird species composition. Our results illustrate the need to integrate species composition (controlling for bird abundance and richness) and their sensitivity to disturbances when predicting the impact of global change on ecosystem functions.     

Generalized avian dispersal syndrome contributes to Chinese tallow tree (Sapium sebiferum, Euphorbiaceae) invasiveness

Abstract. Plants possessing generalized dispersal syndromes are likely to be more invasive than those relying on specialist dispersal agents. To address this issue on a local and regional scale, avian seed dispersal of the invasive alien Chinese tallow tree (Sapium sebiferum (L.) Roxb.) was assessed in forests and spoil areas of South Carolina and along forest edges in Louisiana during the 1997–99 fruiting seasons. Tallow trees in these floristically distinct habitats had a few common and many casual visitors, and considerable species overlap among habitats was found. However, bird species differed in the importance of dispersing and dropping seeds among habitats. Important dispersal agents common to forests and spoil areas of South Carolina included Northern Flicker, American Robin and Red‐winged Blackbird, whereas Red‐bellied Woodpecker and European Starling were important in the former and latter habitat, respectively. In Louisiana, Red‐bellied Woodpecker, American Robin, Northern Cardinal and Eastern Bluebird dispersed many seeds. Nearly all species foraging on seeds were winter residents. Estimated numbers of seeds dispersed and dropped were higher in spoil areas of South Carolina than in Louisiana because of higher numbers of individuals per visit, higher seed consumption and seed dropping rates, and longer foraging durations. Within South Carolina, more seeds were dispersed and dropped in spoil areas than in forests because of higher numbers of birds per visit. These findings show that among habitats, tallow tree attracts diverse but variable coteries of dispersal agents that are qualitatively similar in seed usage patterns. We suggest that its generalized dispersal syndrome contributes to effective seed dispersal by many bird species throughout its range. Effects of differential avian use among locales may include changes in local bird communities, and differing tallow tree demographics and invasion patterns.     

四川嘛咪泽自然保护区不同生境类型鸟类多样性调查

2006年4~5月采用样点法对四川嘛咪泽自然保护区的鸟类组成和种群数量进行了调查,共记录到鸟类7目23科105种,数量1948只,其中国家重点保护鸟类6种,我国特有鸟类7种。鸟类区系以东洋界成分为主。对不同生境鸟类多样性的分析结果表明:1)人工林和灌丛草地生境间的鸟类群落相似性指数最高,灌丛草地和原始林之间鸟类群落相似性最低;2)次生林鸟类多样性指数最高,灌丛草地最低;3)原始林内国家级保护鸟类最多,特有种仅次于次生林;4)林中鸟类垂直分布中间层密度最大。     

Relationships between bird species and tree species assemblages in forested habitats of eastern North America

Aim We examined the relative influence of geographical location, habitat structure (physiognomy), and dominant plant species composition (floristics) on avian habitat relationships over a large spatial extent. Although it has been predicted that avian distributions are more likely to covary with physiognomy than with floristics at coarse scales, we sought to determine, more specifically, whether there remained a significant association between gradients in assemblages of bird species and dominant plant species within a general biome type, after statistically controlling for structural variation and geographical location of sampling sites. Location Our sample consisted of a subset of North American Breeding Bird Census survey sites that covered most of the range of eastern forests, from Florida to Nova Scotia, and west to Minnesota and North Dakota (up to c. 2500 km between sites). Methods We restricted our analyses to the single year (1981) that provided the largest sample of sites (47) for which vegetation data were available within ± 2 years of the avian surveys. We examined the relationship between avian community composition and tree species composition over this series of forested plots. Data were divided into four sets: (1) bird species abundances, (2) tree species abundances, (3) physiognomic or structural variables and (4) geographical location (latitude and longitude). We performed separate detrended correspondence analysis ordinations of birds and trees, before and after statistically partialling out covariation associated with structural variables and geographical location. To gauge the relationship between the two sets of species we correlated site scores resulting from separate ordinations. We also compared continental‐scale patterns of variation in bird and tree assemblages to understand possible mechanisms controlling species distribution at that scale. Results Both bird and tree communities yielded strong gradients, with first‐axis eigenvalues from 0.75 to 0.97. All gradients were relatively long (> 4.0), implying complete turnover in species composition. However, geographical location accounted for < 10% of the total variation associated with any ordination. Prior to partialling out covariation resulting from location and physiognomy, bird species ordinations were strongly correlated with tree species ordinations. The strength of association was reduced after partialling, but one bird and one tree axis remained significantly correlated. There was a significant species–area effect for birds, but not for trees. Main conclusions There was a significant relationship between bird species assemblages and tree species assemblages in the eastern forests of North America. Even after partialling out covariation associated with spatial location and forest physiognomy, there remained a significant correlation between major axes from bird and tree ordinations, consistent with the hypothesis that floristic variation is likely to be important in organizing assemblages of birds within a general biome type, albeit over a much larger spatial extent than originally predicted. Forest tree species ordinations differed from bird species ordinations in several ways: trees had a higher rate of turnover along underlying environmental gradients; trees appeared more patchily distributed than birds at this scale; and tree species were more spaced out along the underlying ecological gradients, with less overlap. By understanding the relationship between bird assemblages and forest floristics, we might better understand how avian communities are likely to change if tree species distributions are altered as a result of climatic changes.     

Phenology of fleshy fruits in a wet sclerophyll forest in southeastern Australia: are birds an important influence?

Summary The hypothesis that seasonality in the production of fleshy fruits in temperate regions is the result of selection by avian seed dispersal agents or avian seed predators was tested in a temperate wet sclerophyll forest in south-eastern Australia. I determined whether ten common fleshy-fruited species produced fruits when potential avian seed dispersers were most abundant or avian seed predators were least abundant. The season of fruit production was not correlated with avian disperser abundance nor with seasonal changes in avian seed predators. Peak fruiting occurred during autumn but fruit-eating birds were equally abundant from spring through to autumn. Avian seed predators (parrots) did not show any seasonal variation in abundance. If dispersers are influencing fruiting seasonality in wet sclerophyll forest, it is likely that changes in social behaviour and feeding patterns of dispersers during autumn, rather than increases in abundance, will be an important influence on fruiting patterns in wet sclerophyll forest. However, environmental and life history factors may also influence phenology.     

Frugivory by Small Vertebrates Within a Deforested, Dry Tropical Region of Central America

Small vertebrates were inventoried within three habitat types in a degraded dry forest region of Panama. Animals were classified as frugivorous if they were observed foraging on fruit or if fecal samples contained mostly or exclusively seeds. Overall, we found that eight bat species and 21 bird species consumed fruit. The greatest numbers of birds were observed within live fences and bird species richness was greatest within riparian forests. Bat assemblages were not significantly different between habitats. The implication is that ecosystem services such as seed dispersal may still be functional in this landscape.     

Functional variation among frugivorous birds: implications for rainforest seed dispersal in a fragmented subtropical landscape

Seed dispersal plays a critical role in rainforest regeneration patterns, hence loss of avian seed dispersers in fragmented landscapes may disrupt forest regeneration dynamics. To predict whether or not a plant will be dispersed in fragmented forests, it is necessary to have information about frugivorous bird distribution and dietary composition. However, specific dietary information for frugivorous birds is often limited. In such cases, information on the seed-crushing behaviour, gape width and relative dietary dominance by fruit may be used to describe functional groups of bird species with respect to their potential to disperse similar seeds. We used this information to assess differences in the seed dispersal potential of frugivorous bird assemblages in a fragmented rainforest landscape of southeast Queensland, Australia. The relative abundance of frugivorous birds was surveyed in extensive, remnant and regrowth rainforest sites (16 replicates of each). Large-gaped birds with mixed diets and medium-gaped birds with fruit-dominated diets were usually less abundant in remnants and regrowth than in continuous forest. Small-gaped birds with mixed diets and birds with fruit as a minor dietary component were most abundant in regrowth. We recorded a similar number of seed-crushing birds and large-gaped birds with fruit-dominated diets across site types. Bird species that may have the greatest potential to disperse a large volume and wide variety of plants, including large-seeded plants, tended to be less abundant outside of extensive forests, although one species, the figbird Sphecotheres viridis, was much more abundant in these areas. The results suggest that the dispersal of certain plant taxa would be limited in this fragmented landscape, although the potential for the dispersal of large-seeded plants may remain, despite the loss of several large-gaped disperser species.     

Water availability drives aboveground biomass and bird richness in forest restoration plantings to achieve carbon and biodiversity cobenefits

To combat global warming and biodiversity loss, we require effective forest restoration that encourages recovery of species diversity and ecosystem function to deliver essential ecosystem services, such as biomass accumulation. Further, understanding how and where to undertake restoration to achieve carbon sequestration and biodiversity conservation would provide an opportunity to finance ecosystem restoration under carbon markets. We surveyed 30 native mixed‐species plantings in subtropical forests and woodlands in Australia and used structural equation modeling to determine vegetation, soil, and climate variables most likely driving aboveground biomass accrual and bird richness and investigate the relationships between plant diversity, aboveground biomass accrual, and bird diversity. We focussed on woodland and forest‐dependent birds, and functional groups at risk of decline (insectivorous, understorey‐nesting, and small‐bodied birds). We found that mean moisture availability strongly limits aboveground biomass accrual and bird richness in restoration plantings, indicating potential synergies in choosing sites for carbon and biodiversity purposes. Counter to theory, woody plant richness was a poor direct predictor of aboveground biomass accrual, but was indirectly related via significant, positive effects of stand density. We also found no direct relationship between aboveground biomass accrual and bird richness, likely because of the strong effects of moisture availability on both variables. Instead, moisture availability and patch size strongly and positively influenced the richness of woodland and forest‐dependent birds. For understorey‐nesting birds, however, shrub cover and patch size predicted richness. Stand age or area of native vegetation surrounding the patch did not influence bird richness. Our results suggest that in subtropical biomes, planting larger patches to higher densities, ideally using a diversity of trees and shrubs (characteristics of ecological plantings) in more mesic locations will enhance the provision of carbon and biodiversity cobenefits. Further, ecological plantings will aid the rapid recovery of woodland and forest bird richness, with comparable aboveground biomass accrual to less diverse forestry plantations.     

Does landscape structure affect resource tracking by avian frugivores in a fragmented Afrotropical forest?

Frugivorous species heavily depend on patchy food resources and are believed to track these in space and time, thereby providing an important seed dispersal function that might be critical toward the regeneration of fruiting plants. However, isolation of suitable food patches due to habitat fragmentation or changes in landscape connectivity may hamper food tracking behaviour and adversely affect populations of both frugivores (through starvation) and food plants (through interruption of seed dispersal). We here test whether density fluctuations in four frugivorous Afrotropical bird species were larger and/or matched fluctuations in ripe fruit densities better in study plots embedded in large tracts of indigenous forest than in equally-sized plots embedded in cultivated lands. We compared these results with those of four non-frugivorous species (out-group) which were not expected to track fruit resources. Whereas densities of both frugivores and fruit crops strongly fluctuated in space and time, these fluctuations were not synchronised, nor did the level of synchrony differ in relation to matrix type. For some but not all bird species, lower densities and smaller temporal fluctuations in forest plots surrounded by cultivation may reflect decreased mobility. The observed fluctuations in bird densities most likely reflect exchange with the surrounding landscape matrix, suggesting that small pockets of fruiting trees in farmland may comprise critical food resources for frugivores inhabiting highly fragmented landscapes, apart from increasing connectivity for both bird and seed dispersal.     

Are mismatches the norm? Timing of flowering,fruiting, dispersal and germination and their fitness effects in Frangula alnus (Rhamnaceae)

The close morphological and temporal links between phases of plant growth and reproduction call for integrated studies incorporating several reproductive phases from flowering to recruitment, and associated plant‐animal interactions. Phenological strategies, as well as plastic phenological response to climate change, incorporate complex interactions between developmental constraints, pollination and seed dispersal. Relationships between reproductive phenology and components of fitness were studied for two years in the north‐temperate, self‐incompatible, insect‐pollinated, and bird‐dispersed shrub Frangula alnus (Rhamnaceae). Fruit set, dispersal, germination and juvenile survival, as well as seed mass and juvenile size were measured in relation to flowering, fruiting and germination time. The results suggest that effects of flowering and fruiting time prevailed in subsequent phases, to some extent as far as to the juvenile phase, but effects of timing were complex and had partly opposing effects on different fitness components. Early flowers had higher fruit‐set and experiments indicated that synchronous peak flowering increased fruit‐set, but later flowers had higher seed mass. Peak fruiting was not associated with peak dispersal. Late fruits derived from late flowers promoted dispersal. Juvenile recruitment was enhanced by increasing seed size. We conclude that the phenology of flowering and fruiting in F. alnus comprises several features, each with different and sometimes counteracting effects on fitness components. From a general perspective, this result implies that we should not expect to find finely tuned matches in timing specifically between flowering and pollinators, and fruiting and seed dispersing birds.     

Bats are Not Birds – Different Responses to Human Land‐use on a Tropical Mountain

Land‐use intensification has consequences for biodiversity and ecosystem functioning, with various taxonomic groups differing widely in their sensitivity. As land‐use intensification alters habitat structure and resource availability, both factors may contribute to explaining differences in animal species diversity. Within the local animal assemblages the flying vertebrates, bats and birds, provide important and partly complementary ecosystem functions. We tested how bats and birds respond to land‐use intensification and compared abundance, species richness, and community composition across a land‐use gradient including forest, traditional agroforests (home garden), coffee plantations and grasslands on Mount Kilimanjaro, Tanzania. Furthermore, we asked how sensitive different habitat and feeding guilds of bats and birds react to land‐use intensification and the associated alterations in vegetation structure and food resource availability. In contrast to our expectations, land‐use intensification had no negative effect on species richness and abundance of all birds and bats. However, some habitat and feeding guilds, in particular forest specialist and frugivorous birds, were highly sensitive to land‐use intensification. Although the habitat guilds of both, birds and bats, depended on a certain degree of vegetation structure, total bat and bird abundance was mediated primarily by the availability of the respective food resources. Even though the highly structured southern slopes of Mount Kilimanjaro are able to maintain diverse bat and bird assemblages, the sensitivity of avian forest specialists against land‐use intensification and the dependence of the bat and bird habitat guilds on a certain vegetation structure demonstrate that conservation plans should place special emphasis on these guilds.