Prey Analysis

To help us build a better understanding of bat foraging behaviour and what specifically they are feeding upon, aquatic invertebrate surveys are underway. Carried out by Craig Macadam of Bradan Aquasurveys Ltd, this work consists of a systematic search of the marginal vegetation at selected sites, followed by a scoop of the sediments on the canal bed.

The initial results show that the canals hold a healthy population of aquatic invertebrates, however the majority of these live solely within the water and would therefore not be available prey for bats.

Aquatic insects, the potential prey for foraging bats, were well represented with ten separate families recorded. The most common of these were the non-biting midges, Chironomidae. These small insects are well known prey for many species of bats and it was anticipated that they would make up the majority of specimens found. The samples collected can now be identified to species level, thus allowing flight periods, adult sizes, and hence the potential for the species to be a prey item for bats to be determined.

Our ongoing research will include the following areas of study :-

• Surveying for flying insects during periods when bats are active.

• Analysis of bat faeces to establish prey consumed.

• Aquatic invertebrate surveys.

• Water temperature and illumination relative to insect emergence.

• Bat foraging relative to insect emergence.

• Water quality using Average Score Per Taxon modelling.

• The relationships between bats and their associated ectoparasites