Factors influencing post-fire dynamics of Sardinian and Dartford Warblers in Mediterranean shrublands

We studied the post-fire dynamics of two Mediterranean warblers (the Sardinian (Sylvia melanocephala) and the Dartford Warbler (Sylvia undata)) to determine whether these were influenced by local habitat recovery or by external population trends unrelated to the occurrence of fire. We used the point-count method to survey warblers from the first to the sixth breeding seasons after fire in burnt and unburnt control zones of the Iberian Peninsula. Both species increased similarly in the burnt zone until the fourth year after fire, but the Dartford Warbler increased faster than the Sardinian Warbler from then on. Six years after fire, the abundance of the Dartford Warbler was even higher in the burnt zone than in the control, where the population of this species remained constant during the study period. In contrast, a parallel increase in the populations of Sardinian Warbler in both zones was observed, thus suggesting that processes other than fire were profoundly involved in the dynamics of this species in the burnt zone. Our results indicate that the post-fire dynamics of these two species greatly differ, the Dartford Warbler being highly influenced by local habitat changes in the burnt zone and the Sardinian Warbler by population trend on a larger scale than the disturbed habitat.