HABITAT USE BY BATS ALONG RIVERS IN NORTH-EAST SCOTLAND

Habitat use by foraging bats near Aberdeen, northeast Scotland (57 deg rees N), was assessed by means of ultrasound detectors. Common pipistr elles Pipistrellus pipistrellus (Schreber) and Daubenton's bats Myotis daubentoni (Kuhl) foraged mainly over the rivers or over nearby ponds , occasionally near trees. The river Dee, which is fed by mountain str eams and bordered by woodland for much of its length, and the river Yt han, which drains farmland and is bordered mostly by treeless fields a nd pastures, did not differ significantly in foraging bat density. Lik ewise, bat density over the water did not differ between treeless and wooded parts of the rivers, and was not influenced by the presence of bridges. However, bridges were probably used as mating stations by pip istrelles, as indicated by the high incidence of low frequency calls i n autumn. The result extends previous knowledge by revealing the impor tance of the river, rather than the riparian vegetation, as feeding ha bitat for two of the three common bat species in Scotland.