Etude comparée de l’adaptation des mésanges du genre Parus aux différentes essences forestières du bassin méditerranéen occidental

Résumé En

Data on some breeding parameters, especially clutch-size, of the Blue Tit from various mediterranean study-sites are presented (Table I). In the european oakwood vegetation belt (Southern Sweden to Southern France) clutch size remains more or less the same (10 to 12 eggs) (Table II). Conversely, in the evergreen oak vegetation belt (Mediterranean region), clutch size progressively diminishes southwards, and reaches its minimum value of 3.5 eggs on the Canary Islands. It is suggested that this is the «quality» of the habitat (i.e. food availability during the breeding season), which plays the «key» role in determining these differences in clutch sizes. The role of «environmental quality» is further emphasized by comparatives studies, still in progress, on the breeding patterns of Blue Tits and Great Tits in an evergreen oak woodland and in a deciduous oak woodland, both located in the same geographical area. The data at hand (Tables III and IV) show that there are important differences between these two kinds of habitats for such parameters as the onset of breeding, clutch size, and breeding success. The birds generally perform better in deciduous woodland.