Preservation of foraging habitats is a fundamental approach to bat conservation. Yet, knowledge on the primary foraging sites of Mediterranean bats remains scarce, particularly during the summer when the availability of prey can be limiting. This study was designed to determine in which habitats bats forage in Southern Portugal, during this potentially stressful period. During the summers of 1994 and 1995, bat foraging activity was monitored in representative habitat types using an ultra-sound detector. The number of feeding-buzzes and bat-passes were counted and species identified through the analysis of recorded echolocation calls. None of the recorded species restricted its foraging activity to a single habitat type, but water sites were preferred by most bats. Tadarida teniotis was an exception to this habitat use. Further analysis confirmed that riparian habitats when surrounded by autochthonous broad-leaved forests seem to provide optimal foraging areas for bats during summer. Opposite, water sites within habitats resulting from intensive agriculture or forestry, provide very poor foraging areas. The typical Mediterranean landscape of Iberia, dominated by oak-woodlands and with numerous, scattered and well vegetated water sites, seems to grant optimal foraging habitat for bats during summer. However, this landscape is itself at risk. Current production demands are causing substantial land-use changes and, despite some European programmes on the preservation of Mediterranean oak woodlands and their biodiversity, the furtherance of this landscape is at stake. The preservation of traditional management strategies of oak-woodlands and associated water sites should be strongly encouraged.