Bibliothèque Tour du Valat

Se connecter

Mot de passe oublié ?
Pas encore inscrit ?

La Tour du Valat

Institut de recherche pour la conservation des zones humides méditerranéennes

Détail

Ajouter au panier

Ajouter au panier

Lien vers la notice

Titre :	Winter bird communities in an agricultural landscape (Schweitenkirchen, Upper Bavaria) - influence of local climate conditions, landscape structure, and landuse systems
Auteurs :	Hans Utschick, Auteur ; Josef Repplinger Und, Auteur ; Bernhard Foerster, Auteur
Type de document :	Article
Dans :	Ornithologischer Anzeiger (54(1) AUG 2015)
Article en page(s) :	13-40
Résumé :	From 2004/05 to 2013/14 winter birds were counted by quantitative grid mapping (250 m x 250 m units) over 57 km(2) of a hilly landscape 50 km north of Munich. Models for the distribution of farmland and open landscape birds are developed based on a fine grained land use classification, on landscape topography and on winter climate conditions. To this end, bird species are classified into groups representing preference for open land, vicinity of settlements, cultural landscape, and agriculture (with Linnet as key species).Due to the unstable distribution of winter birds in open landscapes, the models show that an estimation of winter bird densities is only possible for larger land units such as the study area. At lower scale (6,25 ha units) the models indicate whether winter birds may be expected or not, and important variables for the evaluation of winter bird habitats in open landscapes can be related. Winter bird abundances in open landscapes are positively influenced by high proportions of small scaled hop and winter cereal complexes together with hedges and small tree groups; abundances within mostly treeless areas are positively influenced by richness of small, not economically used landscape structures like field margins, small water bodies or extensively used habitat islands, served by an extensive network of unsurfaced tracks and this especially within areas near settlement. The models show no preference for winter fallows or set-aside land, which many other studies show to be important for winter bird abundance. This may be because the few such resources in the study area are exhaustively used by birds by late autumn. Where topography is concerned, landscape structures toward the top of broad ridges are important, mainly for the Linnet. As was expected, frosty, snowy winters cause low winterbird densities in open landscapes. Icy early winters cause departure of species typical for farmland winter landscapes such as the Goldfinch; mid-winter frosts cause departure of more ubiquitous species such as the Chaffinch and the Tree Sparrow and their movement from open landscape closer to settlements; cold late winters also cause departure of typical cultural landscape species like Greenfinch and Yellowhammer.Within the study area, only models for ubiquitous openland winter birds showed a negative influence caused by the increasing and more large scaled production or energy plants like maize or rape. But there are hints, that the winter densities of typical farmland birds are lower in areas with large scaled energy plant production compared to fine grained landscapes, diverse land use systems and fallows. Within a hop-growing region, winter birds in open landscapes will benefit mainly from a hop production with undersown crops and retraction of cultivation work to early spring. In woodlands and especially in small woods near settlements, winter bird densities are higher than in the open landscape. But singularities like temporary large scale fallow effects following heavy damage from a hailstorm or short time set-aside of large fallows in response to subsidies indicate, that winter birds prefer open landscapes, if extensive land use systems offer high winter seed resources. A further expansion of organic farming could have similar effects. Winter populations of the Linnet show narrow affinity to ca. 30 ha units of optimally structured open landscapes. This narrow dependence is both dangerous for the species, but presents the Linnet as a key species for optimizing agricultural landscapes by promotion programs at landscape level.

FAQ

Infos pratiques

Heures d'ouverture et contact

Lundi , mardi et jeudi de 9h à 12h et de 13h à 17h00 : ouverture au public ...

Liens utiles

A-
A
A+