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 :	Palearctic migrants in Africa - Competition with tropical species.
Auteurs :	Volker Salewski, Auteur ; Franz Bairlein, Auteur ; Bernd Leisler, Auteur
Type de document :	Article
Dans :	Vogelwarte (44(1) FEB 2006)
Article en page(s) :	1-15
Langues:	Allemand
Résumé :	one of the main questions of former studies on the wintering ecology of long distance migrants is how migrants partition resources with residents in their winter quarters and to what extent competition between the two groups plays a role for the evolution of the present avian communities. Here, we summarize the results of our own studies from Ivory Coast that focused on niche partitioning of the Palaearctic Pied Flycatcher and Willow Warbler and Afrotropical species in their respective guilds with respect to habitat selection, microhabitat use and foraging ecology with the aim to (1) compare them with similar former studies, (2) to discuss whether there are general ecological traits which are characteristic for long-distance migrants, (3) discuss the possibility to detect competition between migrants and residents and (4) to discuss key questions for further studies. Our study revealed that migrants do not generally use more open habitat with respect to tree density than Afrotropical species and do not forage in a generally more open microhabitat. However, migrants were found most frequently in habitats with highest structural diversity and the most pronounced seasonal changes. They were also the only species within their guilds that were found in all three available habitats. The Palaearctic species showed the highest diversity of foraging techniques and in most cases, foraging substrate within their guilds. Pied Flycatchers were intraspecifically territorial but interspecific interactions were neither often observed in Pied Flycatchers nor in Willow warblers which regularly occurred in mixed species flocks with Senegal Eremomelas. A comparison of our results with those of former studies revealed that it is not possible to generalize the migrants' behaviour because there are species specific requirements which may vary with e.g. season and geography. Migrants however, seem to be more generalists than residents, in many aspects of their use of various resources. This may allow both groups to coexist but it is not clear whether this flexibility is an adaptation to survive on the wintering grounds or a prerequisite for the evolution of bird migration. Recent studies, however, questioned the notion about the migrants' flexibility. The solution to this apparent contradiction might be that different approaches were used to deal with this question. Migrants might be flexible when an ecological approach is used because they use a diverse repertoire of behaviours but might not be flexible from an evolutionary point of view because the use the same repertoire of foraging behaviours under varying conditions. With respect to the question whether competition shapes present migrant/resident communities it is discussed that probably neither mere chance nor exclusively interspecific competition is the key factor for the evolution of present resident/migrant communities. instead a set of factors seem to have acted in the past and at present including interspecific competition.It is further argued that problems with respect to studies of mutual influence of the ecology of migrants and residents are (1) to see migrants as a homogenous group although different species use different habitats and resources, (2) the dichotomous approach that concerns only a long-distance migrating lifestyle versus a resident lifestyle because it does not account for some migrants being territorial for several months in Africa and widespread intra-African migration and (3) that individual consequences for survival and fitness through the presence of other individuals are hrdly investigated and therefore, discussions about competitive situations remain speculative. This problems have to be overcome to find out more about the mutual influence of Palaearctic migrants and Afrotropical species. It is proposed, that investigations of mixed species flocks of migrants and African species or consequences of habitat selection of territorial migrants could answer some of these questions.

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+