Forest edges have high conservation value for bird communities in mosaic landscapes

A major conservation challenge in mosaic landscapes is to understand how trait‐specific responses to habitat edges affect bird communities, including potential cascading effects on bird functions providing ecosystem services to forests, such as pest control. Here, we examined how bird species richness, abundance and community composition varied from interior forest habitats and their edges into adjacent open habitats, within a multi‐regional sampling scheme. We further analyzed variations in Conservation Value Index (CVI), Community Specialization Index (CSI) and functional traits across the forest‐edge‐open habitat gradient. Bird species richness, total abundance and CVI were significantly higher at forest edges while CSI peaked at interior open habitats, i.e., furthest from forest edge. In addition, there were important variations in trait‐ and species‐specific responses to forest edges among bird communities. Positive responses to forest edges were found for several forest bird species with unfavorable conservation status. These species were in general insectivores, understorey gleaners, cavity nesters and long‐distance migrants, all traits that displayed higher abundance at forest edges than in forest interiors or adjacent open habitats. Furthermore, consistently with predictions, negative edge effects were recorded in some forest specialist birds and in most open‐habitat birds, showing increasing densities from edges to interior habitats. We thus suggest that increasing landscape‐scale habitat complexity would be beneficial to declining species living in mosaic landscapes combining small woodlands and open habitats. Edge effects between forests and adjacent open habitats may also favor bird functional guilds providing valuable ecosystem services to forests in longstanding fragmented landscapes.     

Birds,Cattle, and Bracken Ferns: Bird Community Responses to a Neotropical Landscape Shaped by Cattle Grazing Activities

Large areas of tropical moist forests have been converted to cattle pastures, generating complex landscapes where different habitats are represented by small patches with an uneven spatial distribution. Here, we describe how bird communities respond to the different elements present in a livestock landscape that was originally dominated by tropical moist forest. We surveyed six habitats: open pastures, pastures with shrubs, early‐ and middle‐secondary forests, mature forest, and pastures invaded by bracken ferns (Pteridium aquilinum). Bird diversity was high in secondary and mature forests, and low in fern‐invaded sites and open pastures. Fern‐dominated sites had the lowest bird species richness, and trophic guild diversity of all habitats. Habitat structure affected both bird species richness and densities in similar ways. Tree species richness was the habitat attribute that had a bigger positive effect on bird species richness. Bird community structure varied among sampled habitats, separating habitats in two major groups (forests and pastures). Our data indicate that bracken fern‐invaded pastures were the worst habitat condition for avian communities. To increase bird diversity, we recommend to eliminate or manage bracken fern and to increase shrub and tree cover in open pastures to provide food resources and shelter for birds. Finally, we encourage the maintenance of secondary and mature forest remnants as a strategy to conserve resident birds within a landscape dominated by livestock activities.     

Richness and abundance of birds in riparian forest belts of varied breadths at the Sesesmiles river microwatershed, Copan, Honduras

Richness and abundance of birds in riparian forest belts of varied breadths at the Sesesmiles river microwatershed, Copan, Honduras. Riparian forests protect many species of plants and animals. We studied bird communities in riparian forest belts of the Sesesmiles river microwatershed, Copan, Honduras (140 degrees 43' 12" - 140 degrees 58' 35" N, 88 degrees 53' 23" - 89 degrees 14' 17" W). The main goal was to explore the effects of belt breadth on the richness and abundance of avian species visiting these forests. We selected 20 belts, and randomly established 30 observation points to monitor bird presence in the dry (March-April 2005) and rainy (June-July 2005) season (N= 60 observations). A total of 1,294 birds belonging to 145 species were recorded. Bird diversity was significantly correlated to the breadth of the riparian belts, with a greater number of species and individuals in belts 50 m wide or wider. Insectivorous and nectarivorous birds were the most abundant guilds. All bird species identified depend to some degree on riparian forests and are affected by belt breadth. Riparian belts over 50 m should be kept or established in order to conserve bird populations within agricultural and fragmented landscapes in similar tropical areas.     

High Bird Species Diversity in Structurally Heterogeneous Farmland in Western Kenya

Tropical ecosystems are globally important for bird diversity. In many tropical regions, land‐use intensification has caused conversion of natural forests into human‐modified habitats, such as secondary forests and heterogeneous agricultural landscapes. Despite previous research, the distribution of bird communities in these forest‐farmland mosaics is not well understood. To achieve a comprehensive understanding of bird diversity and community turnover in a human‐modified Kenyan landscape, we recorded bird communities at 20 sites covering the complete habitat gradient from forest (near natural forest, secondary forest) to farmland (subsistence farmland, sugarcane plantation) using point counts and distance sampling. Bird density and species richness were on average higher in farmland than in forest habitats. Within forest and farmland, bird density and species richness increased with vegetation structural diversity, i.e., were higher in near natural than in secondary forest and in subsistence farmland than in sugarcane plantations. Bird communities in forest and farmland habitats were very distinct and very few forest specialists occurred in farmland habitats. Moreover, insectivorous bird species declined in farmland habitats whereas carnivores and herbivores increased. Our study confirms that tropical farmlands can hardly accommodate forest specialist species. Contrary to most previous studies, our findings show that structurally rich tropical farmlands hold a surprisingly rich and distinct bird community that is threatened by conversion of subsistence farmland into sugarcane plantations. We conclude that conservation strategies in the tropics must go beyond rain forest protection and should integrate structurally heterogeneous agroecosystems into conservation plans that aim at maintaining the diverse bird communities of tropical forest‐farmland mosaics.     

Bird community shifts related to different forest restoration efforts: A case study from a managed habitat matrix in Mexico

Although increased attention is being paid to animals when studying restoration processes, little is known on the effects that different restoration efforts have on birds. In this study we evaluated the variation of bird communities in a managed landscape that includes cropfields and two different restoration strategies. To evaluate possible differential effects of both restoration strategies (plus former-state and natural-state comparisons as controls), we compared their bird communities. After five growing seasons, bird species richness was highest in native forest remnants and lowest in cropfields. Although species richness values from the restoration treatment did not show differences in relation to those from the forest treatment, values for the reforestation treatment did. Bird densities were highest in the forests and alike in cropfield, reforestation, and restoration treatments. However, bird communities recorded in the restoration treatment were fairly even when compared to the reforestation treatment, and highest bird species composition similarity was recorded between the restoration and forest treatments. These results suggest that the studied restoration treatment attracts a higher number of bird species in relation to former states and thus enhance bird richness. Also, we demonstrate that restoration efforts that include more actions can affect more ecosystem components. In this study, nurse plants not only offered a quick growing structural vegetation component that enhanced habitat structure, but also provided abundant food resources for birds. Given the scarcity of comparable habitat matrices to replicate our study, our results should be taken with caution as they are not generalizable to all Mexican temperate forest conditions. Although further studies need to address whether restoration practices using Lupinus elegans positively affect bird primary population parameters (e.g., survival, reproduction), our results show that restoration practices that include nurse plants can promote rich bird communities after only 5 years from the implementation of restoration measures.     

北京小龙门森林鸟类群落划分与生态分析

森林鸟类是森林陆栖脊椎动物中种类和数量最丰富的动物类群 ,它们对于促进森林天然更新、传播植物种子及花粉、控制森林害虫和害兽等方面都起着重要作用。关于小龙门林区鸟类群落结构的研究已有报道[1 ] ,但是对于小龙门林区鸟类群落的划分未见有专门报道 ,我们于 1 992年 1 0月～1 993年 2月 ,1 993年 4～ 1 2月 ,1 994年 2～ 8月对北京小龙门林区所有 8条自然沟和 1条公路进行了调查 ,目的在于了解小龙门林区不同林型、海拔等区域的鸟类种类组成和数量状况 ,探讨不同区域的鸟类群落的划分及其影响因素。1　研究地点及方法小龙门林区位于北…     

Avifauna of two upland evergreen forest reserves,the Atewa range and Tano Offin,in Ghana

Ntiamoa-Baidu, Y., Asamoah, S.A., Owusu, E.H. & Owusu-Boateng, K. 2000. Avifauna of two upland evergreen forest reserves, the Atewa Range and Tan0 Offin, in Ghana. Ostrich 71 (1 & 2): 277–281.

Data are presented on the avifauna of two Upland Evergreen forest reserves in Ghana: Atewa Range Forest Reserve and the Tano Offin Forest Reserve. The data obtained for the two reserves using three survey techniques: transect counts, timed species counts and mist-netting are compared. A total of 105 species were recorded for the Atewa Range Forest Reserve while the Tano-Offin Forest Reserve yielded 110 species. Mean species encounter rate in the transect counts at Atewa was 24.2 per km while individual bird encounter rate was 52.6 per km; encounter rates at Tano Offin were 31.2 per km. and 98.2 per km for species and individual birds respectively. The most common species encountered in Atewa was the Yellow-whiskered Greenbul Andropadus latimstris (7.1% of observations in transect counts and 6.7% in spot counts), while the Green-crested Touraco (6.6% of transect counts) and Green Hylia (5.7% of spot counts) were the most abundant at Tan0 Offin. The records for Atewa included four globally threatened species while Tano yielded three threatened species. Two species of birds, the Equatorial Akalat Sheppardia aequatorialis and the yellow-bellied Greenbul Phyllastrepus flavostn'atus were recorded for the first time in Ghana from the two reserves. The bird community at Tan0 Ofin was significantly more diverse than that at Atewa. In both reserves, spot counts yielded more species (67.6% and 74.5% of total recorded at Atewa and Tan0 respectively), than transect counts and mist nets. 31 species recorded in both spot counts and transect counts at Atewa were not captured in mist nets, while nine species caught in mist nets were not recorded by the two methods. The figures for the Tano Offin reserve were 43 and six respectively. We conclude that of the three survey techniques, the timed species counts offer the most comprehensive results for rapid assessment of forest avifauna, but a combination of all three methods is necessary for complete coverage. The need for management of the two reserves to maintain their unique biodiversity in the face-of threats from mining and logging is discussed.     

Bat and bird diversity along independent gradients of latitude and tree composition in European forests

Species assemblages are shaped by local and continental-scale processes that are seldom investigated together, due to the lack of surveys along independent gradients of latitude and habitat types. Our study investigated changes in the effects of forest composition and structure on bat and bird diversity across Europe. We compared the taxonomic and functional diversity of bat and bird assemblages in 209 mature forest plots spread along gradients of forest composition and vertical structure, replicated in 6 regions spanning from the Mediterranean to the boreal biomes. Species richness and functional evenness of both bat and bird communities were affected by the interactions between latitude and forest composition and structure. Bat and bird species richness increased with broadleaved tree cover in temperate and especially in boreal regions but not in the Mediterranean where they increased with conifer abundance. Bat species richness was lower in forests with smaller trees and denser understorey only in northern regions. Bird species richness was not affected by forest structure. Bird functional evenness increased in younger and denser forests. Bat functional evenness was also influenced by interactions between latitude and understorey structure, increasing in temperate forests but decreasing in the Mediterranean. Covariation between bat and bird abundances also shifted across Europe, from negative in southern forests to positive in northern forests. Our results suggest that community assembly processes in bats and birds of European forests are predominantly driven by abundance and accessibility of feeding resources, i.e., insect prey, and their changes across both forest types and latitudes.     

四川老君山自然保护区不同生境鸟类多样性研究

2006年4~5月采用"点样带法"(point transects)对四川老君山自然保护区的鸟类物种组成和种群数量进行了调查,共记录到85种鸟类,分属7目22科。其中,国家级保护鸟类5种,我国特有种13种,优势种4种。把调查区域划分为3种生境:原始林、次生林和人工林,并对各生境鸟类群落的鸟类数量级、鸟类群落的物种多样性、鸟类群落间的相似性进行了比较分析,其结果表明:1)国家级保护鸟类在原始林中最多,次生林中最少;我国特有种则是次生林中最多,人工林中最少。2)鸟类群落Shannon-Wiener物种多样性指数原始林最高,人工林最低。3)原始林和次生林之间的B ray-Curtis相似性指数最高,原始林和人工林之间相似性指数最低。     

Bird communities of dry forests and oak woodland of western Mexico

Bird species-richness and densities were studied in spring and autumn of 1991 and 1992 in dry forest and oak woodland in western Mexico. Classification of the vegetation resulted in the identification of six dry forest types: from thorn forests, dominated by Acacia , through broad-leaved tree forest (typical dry forest of western Mexico) and small-leaved tree forest to Ipomoea forest. Oak woodland and mixed woodland, which are a transition between dry forest and the more mesic oak woodland, formed two further forest types. In the study area as a whole, bird densities were higher in autumn, following the rainy season, than in spring, which is the dry season, and the beginning of the breeding season. Densities in the two autumns were very similar (mean 93 ± 7.8 birds per 2.8 ha) but differed significantly between spring 1991 (57 ± 2.2 per 2.8 ha) and spring 1992 (70 ± 3.2 per 2.8 ha), possibly due to unseasonal rain in 1992. In autumn, bird densities were highest in thorn forests and lowest in broad-leaved tree forests and oak woodland. In spring 1991, bird densities were highest in Prosopis thorn forest and mixed woodland, and lowest in oak woodland. Bird species-richness was low in oak woodland, in both seasons, and high in mixed woodland and Ipomoea forest in spring. Bird species composition between forest types was more similar in the spring than autumn. The spring similarity in species composition is explained by the presence of generalist species in times of food scarcity during the dry season, and by the homogeneity of the predominantly leafless vegetation. Comparison with the bird species composition of a dry forest in Venezuela and the Pacific coast of Mexico indicates that the sites in the present study have an intermediate number of species. Although the present study recorded a smaller number of bird species than on the Pacific coast, 16 were different, expanding the total for Mexican dry forest by 14% from 118 to 134.     

Ecological association of habitats and bird species during the breeding season in southeastern New South Wales

Bird communities in southeastern New South Wales, as determined by classification and ordination techniques, were seldom discrete. The most cohesive assemblage was associated with wet sclerophyll and rainforest habitats. These moist forests also supported the richest avifaunas and had high population densities. Although most birds occurred throughout the region, most species were uncommon. Of the 116 species recorded, 51 (44%) were found on fewer than 10% of the 143 plots censused. Only 19 species occurred on more than half the plots, with six of these recorded on more than 90% of the plots. Other than a small group of birds primarily restricted to moist forest, only the most common and widely distributed species regularly occurred together. Species were grouped with habitats on an elevational gradient from coastal forests to the tablelands. Within this elevational range, species were associated with major structural features of the vegetation. In terms of bird assemblages, open habitats were distinguished from those with dense vegetation. Plots which had been recently logged were separated from mature forest. The results indicate that plans for wildlife management should consider both the assemblages of species which are associated with major forest habitats and the requirements of individual species.     

Changes in Nothofagus pumilio forest biodiversity during the forest management cycle. 2. Birds

Human activities, such as logging, modify the forest structure and the microenvironments of the original Nothofagus forests. The aims of this work were to evaluate changes in the diversity and relative abundance of birds and to analyze their trophic relationships with insect and plant communities along the Nothofagus pumilio forest management cycle. Data was collected using a point sampling method along transects located in different forest structures during the summer season, by direct (sight) and indirect (hearing) recognition following sunrise. Bird diversity and abundance significantly varied along the forest management cycle. Seven new species appeared after harvest, but the total number did not vary by the end of the forest management cycle, and there was no significant loss of species. Bird abundance was directly related to the insect abundance and plant biomass. Relationship between groups (lower plants, monocotyledons and dicotyledonous) is also discussed. Major studies in bird ecology are necessary to develop new silvicultural alternatives based on the more sensitive species to harvest. Forest management strategies and mitigation alternatives must be incorporated into forest planning in order to maintain the original structure of bird communities and the equilibrium with other forest species.     

Changes in avian species composition following surface mining and reclamation along a riparian forest corridor in southern Indiana

Data on the response of bird communities to surface mining and habitat modification are limited, with virtually no data examining the effects of mining on bird communities in and along riparian forest corridors. Bird community composition was examined using line transects from 1994 to 2000 at eight sites within and along a riparian forest corridor in southwestern Indiana that was impacted by an adjacent surface mining operation. Three habitats were sampled: closed canopy, riparian forest with no open water; fragmented canopy, riparian forest with flood plain oxbows; and reclaimed mined land with constructed ponds. Despite shifts in species composition, overall bird species richness, measured as the mean number of bird species recorded/transect route, did not differ among habitats and remained unchanged across years. More species were recorded solely on mined land than in either closed forest or forested oxbow habitats. Mined land provided stopover habitat for shorebirds and waterfowl not recorded in other habitats, and supported an assemblage of grassland-associated bird species weakly represented in the area prior to mining. A variety of wood warblers and other migrants were recorded in the forest corridor throughout the survey period, suggesting that, although surface mining reduced the width of the forest corridor, the corridor was still important habitat for movement of forest-dependent birds and non-resident bird species in migration. We suggest that surface mining and reclamation practices can be implemented near riparian forest and still provide for a diverse assemblage of bird species. These data indicate that even narrow (0.4 km wide) riparian corridors are potentially valuable in a landscape context as stopover habitats and routes of dispersal and movement of forest-dependent and migratory bird species.     

Winter bird communities in forest plantations in western England and their response to vegetation,growth stage and grazing

This paper presents the results of a study of wintering bird communities across a wide range of coniferous, broadleaved and mixed forest stands in the Forest of Dean, western England. Bird communities of broadleaved and coniferous woodland differed with respect to their species composition. The mean number of individual birds recorded increased linearly with woodland age and was not influenced by woodland type, stand size or the presence of grazing. Woodland age and type and the presence or absence of grazing all significantly influenced bird species richness and the proportions of the bird community made up by granivores, insectivores and omnivores. Broadleaved stands held more species than coniferous stands. Ungrazed stands held significantly more species, particularly seed-eating species, than grazed stands and this effect was independent of woodland type. Ordination was used to relate variation in tree species composition and stand structure to bird community composition. A larger number of species was associated with broadleaved stands and stands with abundant undergrowth than was associated with coniferous stands or stands with little undergrowth. Woodland age had less effect on bird community composition than the extent of undergrowth and the conifer to broadleaf ratio. The results of this work have relevance to the enhancement of winter bird communities in commercial forests.     

三峡重庆库区不同鸟类群落的物种组成及多样性研究

1996～1997年,对三峡工程重庆库区的鸟类群落物种组成和种群数量进行了调查,共调查记录库区鸟类15目48科226种,数量18929只。用鸟类数量级划分、Sorensen相似性指数、Shannon-Wiener指数和Pielou指数分析库区各种生境鸟类群落物组成和物种多样性结果表明：1）库区天然林、人工林、灌草丛和水域生境中鸟类群落的组成与农田生境具有较高的相似性,尤以人工林和农田的相似性最高;2）库区人工林生境鸟类群落物种多样性最高;3）库区由于长期以来人类活动的影响,生境日趋单一,已逐渐形成一种以农田灌丛鸟类为主的鸟类生态系统。     

Birds of a high-altitude cloud forest in Alta Verapaz, Guatemala

The Northern Central American Highlands have been recognized as endemic bird area, but little is known about bird communities in Guatemalan cloud forests. From 1997 to 2001 a total of 142 bird species were recorded between 2000 and 2400 masl in cloud forest and agricultural clearings on Monta?a Caquipec (Alta Verapaz, Guatemala). The bird community is described based on line transect counts within the forest. Pooling census data from undisturbed and disturbed forest, the Gray-breasted Wood-Wren (Henicorhina leucophrys) was found to be the most abundant species, followed in descending order by the Common Bush-Tanager (Chlorospingus ophthalmicus), the Paltry Tyrannulet (Zimmerius vilissimus), the Yellowish Flycatcher (Empidonax flavescens), the Ruddy-capped Nightingale-Thrush (Catharus frantzi), and the Amethyst-throated Hummingbird (Lampornis amethystinus). Bird communities in undisturbed and disturbed forest were found to be similar (Serensen similarity index 0.85), indicating low human impact. Of all recorded species, approximately 27% were Nearctic-Neotropical migratory birds. The most abundant one was the Wilson's Warbler (Wilsonia pusilla). The Monta?a Caquipec is an important area for bird conservation, which is indicated by the presence of four species listed in the IUCN Red List (Highland Guan Penelopina nigra, Resplendent Quetzal Pharomachrus mocinno, Pink-headed Warbler Ergaticus versicolor, Golden-cheeked Warbler Dendroica chrysoparia), and 42 Mesoamerican endemics, of which 14 species are endemic to the Central American Highlands. The results presented here will be useful as baseline data for a long-term monitoring.     

广西大明山鸟类群落组成、区系成分和垂直分布

为了了解鸟类组成和海拔分布状况,利用样线法和固定调查点法于2007~2015年对广西大明山的鸟类进行了研究。在大明山共记录鸟类337种,隶属于17目56科。繁殖鸟类(包括留鸟和夏候鸟)共计234种,占大明山鸟类种数的69.4%,具有明显优势,构成了大明山鸟类区系组成的主体。大明山具有典型的华南区向华中区过渡的鸟类区系特征,67.1%的繁殖鸟类属于东洋型的种类。随着海拔的增加,东洋型的种类逐渐减少。依据海拔梯度和植被的不同,可以将大明山鸟类分成6个类群,鸟类总种数和繁殖鸟类种数均以海拔500~900 m的范围内最多,海拔200~500 m范围内鸟类次之。由于大明山地处热带南缘,本研究将为今后监测气候变暖对鸟类的影响提供依据。     

Angola’s central scarp forests: patterns of bird diversity and conservation threats

Despite Angola’s central scarp forests being recognised as a critical global priority for bird conservation, fine-scale information on threatened bird distributions and patterns of bird diversity are lacking. These data are essential to identify sites within the Western Angola Endemic Bird Area that should be targeted for conservation. First endemic and near-endemic species and subspecies, and species with isolated populations along the Angolan scarp were identified to highlight taxa of greatest priority for conservation and for use in studying the evolutionary origins of the region. Thereafter survey data collected during 2005 from 13 forest sites along the central scarp was analysed. These data show that there are three distinct bird communities across the width of the escarpment, each associated with a distinctive forest type. Of note is the finding that threatened and Near Threatened endemic species occur almost exclusively in the dry forests adjacent to the main escarpment, rather than in the moistest forests found on the main escarpment, which instead are richer in Congo Basin forest birds. Based on these data, summaries of ranges, populations and conservation threats are given for the seven most threatened bird species. Attention is drawn to threats to the habitats of greatest importance to these species. A conservation area network should be established that encompasses the full spectrum of bird diversity described, to ensure survival of current unique taxa and the future evolutionary potential of the area.     

Effects of forest modification on bird community composition and seed removal in a heterogeneous landscape in South Africa

Human disturbance threatens and modifies forest ecosystems worldwide. Previous studies have investigated the effects of human impact on local bird communities in disturbed forests, but we still lack information on how bird species richness and ecological processes respond to different forest modifications present at a landscape scale. In a heterogeneous South African landscape, we chose six types of indigenous scarp forest, differing in the intensity of human disturbance: continuous natural forests and natural forest fragments in nature reserves, forest fragments in eucalyptus plantations, fragments in the agricultural matrix, forest gardens and secondary forests in game reserves. In 36 study sites, we investigated the bird community using point counts and observed the seed removal of birds at the native tree species Celtis africana. Species richness did not differ among the forest types, but abundance varied significantly with most birds observed in fragments in the agricultural matrix, forest gardens, and secondary forests. The higher bird abundance in these forests was mainly due to forest generalists, shrubland and open country species whereas forest specialists were rarely present. Changes in species composition were also confirmed by multivariate analysis which clearly separated bird communities by forest type. Frugivore abundance in C. africana was highest in natural forest fragments, fragments in the agricultural matrix, forest gardens and secondary forests. The same trend was found for the estimated total number of fruits removed per C. africana tree, though the differences among forest types were not significant. Consequently, modified forests seem to maintain important ecological functions as they provide food sources for generalist species which may, due to their mobility, enhance natural plant regeneration. However, we could show that protected forest habitats are important refugees for specialist species sensitive to human disturbance.