Authors:J. Traba, M. B. Morales, C. P. Carmona, and M. Paula Delgado
, R. Kinks , J. Liira , L. Meléndez , T. Pärt , C. Thies , T. Tscharntke , A. Olszewski and W.W. Weisser . 2011 . Taxonomic and functional diversity of farmland birdcommunities across Europe: effects of biogeography and agricultural
Authors:P. Batáry, A. Kovács-Hostyánszki, C. Fischer, T. Tscharntke, and A. Holzschuh
Hedges and forest edges play a major role in providing nesting sites, food resources and shelter for birds in agricultural landscapes of western and central Europe. We investigated the response of farmland vs. woodland birds at two degrees of isolation of hedges from forest and to vegetation structure. We surveyed 200 m long sections of six forest edges, six hedges connected to forests and six isolated hedges. Species richness and abundance of farmland birds were higher in hedges than in forest edges, species richness and abundance of woodland birds were lower in hedges than in the forest edges. Species richness and abundance of both groups did not differ between connected and isolated hedges. Width and height of hedges and edges did not affect the species richness and abundance of either farmland or woodland birds. Furthermore, bird community composition differed between habitat types (hedge vs. forest edge) and also between hedge isolation levels (hedges connected to forest vs. isolated hedges). Based on our results, we emphasize the importance of hedges in conserving farmland birds and encourage policy makers to support hedge creation and maintenance with landscape-wide management strategies supporting a diverse hedge structure. Both connected and isolated hedges play an important role as they harbour different bird communities.
Authors:L. Redolfi De Zan, C. Battisti, and G. Carpaneto
The awareness of the importance of deadwood in forest ecosystems has increased in recent decades. Today, dead wood is recognized as a key factor affecting diversity of forest communities. Hole-nesting birds and saproxylic organisms represent an active part of the animal community through the recycle of decaying wood into the forest soils. Three relict beech forests of central Italy were surveyed for both saproxylic beetles and hole-nesting birds, using two different types of interception traps for the former group and point count method for the latter. The variables of dead wood quality were recorded from ten plots, particularly the decaying class and typology of all the wood debris with a diameter ≥ 5 cm. In order to correlate richness and abundance of beetles and birds in a symmetric way, we used co-inertia analysis (CoIA). To correlate in a predictive way the dead wood attributes (dead wood typology and class decay) with birds and beetles assemblages we used partial redundancy analysis (RDA). Our results showed a significant relationship between saproxylic beetle and hole-nesting bird communities. Three dead wood variables (the volume of standing dead trees, stumps and large branches on the ground) appeared to be good predictors of saproxylic beetle richness while the volume of standing dead tree and of dead trees on the ground were the same for hole-nesting birds. These results suggest specific recommendations useful for forest management and planning.
The acceleration of grassland loss on the global scale has been reported in many studies, which is often attributed to the combination of land use change and increased variability of climatic processes. Extensive steppe national parks serve as an ideal study site for grassland conservation, especially wilderness areas where the natural effects of grazing on wildlife can still be tracked. In our study we aim to investigate the effects of habitat structure, grazing type and intensity as well as climatic variables on species abundance, species richness and abundance of functional groups of ground-breeding bird species in the largest compact alkali grassland area of central Europe. We applied the information theoretic approach estimating the importance of ecological predictors according models of substantial support. The main result of our study shows that ground-breeding bird communities in steppe areas exhibit highly species-specific responses to the species of grazers, grazing intensity, habitat composition and climatic predictors. Across the most supported models, species-specific habitat composition values were the most supported predictors. Our findings show that although the response of ground-breeding birds to vegetation, grazing and climatic predictors is highly species-specific, consistent patterns of responsiveness to grazing and climatic patterns emerge, which calls for long-term studies on the combined effects of climatic variability and management of grazing systems.
Authors:C. Wehenkel, A. Reyes-Martínez, J. H. Martínez-Guerrero, C. Pinedo-Alvarez, and C. A. López-Sánchez
Bird migration constitutes a redistribution of bird diversity that radically changes the composition of the bird community worldwide. It comprises about 19% of the world’s bird species. Several studies have indicated that changes in avian community structure and differences in bird richness in different seasons are mainly driven by seasonality and by winter harshness, and that the associated costs increase with the distance involved. Western Mexico is an important wintering area for most passerines that breed in western North America, and that travel long on the long-distance Central and Pacific migration routes. In this study, we examined bird species richness and diversity during the breeding and wintering seasons in the Central Sierra Madre Occidental (SMO), North Durango (Mexico) in relation to i) tree species diversity, ii) tree dimension, iii) forest stand density and site quality, iv) density and dimension of snag trees, and v) various climate variables. The overall aim of the study was to determine how the observed associations between bird species diversity and variables i-v are affected by the season considered (breeding or wintering). The diversity of bird species in the breeding season was not affected by any of the climate and forest stand variables considered. In contrast, bird species diversity in the wintering season was significantly and weakly to moderately associated with climate variables, tree species diversity and stand density, although not with density or dimension of snag trees. Bird species diversity was higher at lower elevations and in drier and warmer locations of the SMO. The association detected is therefore mainly a local migratory phenomenon.