FOOD OF THE SEROTINE BAT, EPTESICUS-SEROTINUS - IS FECAL ANALYSIS A VALID QUALITATIVE AND QUANTITATIVE TECHNIQUE

The diet of Eptesicus serotinus was investigated by faecal analysis an d the validity of this technique as a means of obtaining reliable quan titative results was assessed. Knowledge of what the bats cat will all ow predictions of which habitats contribute most prey. Three male sero tines were kept in captivity during the months of July and August 1991 and fed known quantities of identified insects. With captive E. serot inus the remains of prey appeared within 33 min of first bite and cont inued to appear for up to 32 h after consumption. Scales from two Noct ua pronuba moths consumed were contained in 59 subsequent droppings. S imilarly, fragments of three beetles, Geotrupes stercorarius, were con tained in 28 subsequent faeces. Analysis of the faeces of free-living bats revealed insects from seven orders. Coleoptera were found to be p resent in 96.1% of the droppings examined; the next most frequently fo und order was Lepidoptera, occurring in 14.7%. The beetles were mostly associated with hay meadows (Amphimallon spp. and Melolontha spp.), o r grazed pasture (Aphodius spp. and Geotrupes spp.). Quantitative dete rmination of prey eaten is not possible owing to the large number of t he droppings shown to contain the remains of marker insects and the lo ng period over which they are produced.