Effects of wastewater treatment plant effluent on bat foraging ecology in an urban stream system

Kalcounis-Rüppell, M.C., Payne, V., Huff, S.R., Boyko, A. 2007 To examine effects of WWTP effluent on terrestrial predators in this system we determined prey availability, bat community structure, and bat foraging and commuting behavior at sites above and below WWTPs. We predicted an effect of effluent in the riparian habitat specialist Perímyotís subflaυus but not the habitat generalists Eptesícus fuscus, Lasíurus borealís, or Nyctíceíus humeralís. Nocturnal insect abundance was higher upstream of the WWTPs. There were more Diptera, Coleoptera, and Lepidoptera upstream of the WWTPs whereas there were more Odonata downstream of the WWTPs. There were more E. fuscus upstream of the WWTPs and more P. subflaυus downstream of the WWTPs. Despite the difference in bat community structure up-and downstream of the WWTPs, bat commuting and foraging activity levels were the same; there was no difference in the total number of echolocation sequences we recorded per night up-and downstream of the WWTPs nor was there a difference in the proportion of those sequences that contained a feeding buzz. Our results suggest the effect of anthropogenic nutrients in the stream persists through higher food web trophic levels as we found impacts on nocturnal flying insects as well as two common species of insectivorous bats. Perímyotís subflaυus and E. fuscus may serve as easily tractable terrestrial bioindicators of water quality as influenced by WWTP effluent in this, and other, urban watersheds

Effects of clear-fell harvest on bat home range

We investigated effects of roost loss due to clear-fell harvest on bat home range. The study took place in plantation forest, inhabited by the New Zealand long-tailed bat (Chalinolobus tuberculatus), in which trees are harvested between the ages 26-32 years. We determined home ranges by radiotracking different bats in areas that had and had not been recently clear-fell harvested. Home ranges were smaller in areas that had been harvested. Adult male bats selected 20-25 year old stands within home ranges before and after harvest. Males selected edges with open unplanted areas when harvest had not occurred but no longer selected these at proportions greater than their availability post harvest, probably because they were then readily available. This is the first radiotracking study to demonstrate a change in home range size and selection concomitant with felling of large areas of plantation forest, and thus quantify negative effects of forestry operations on this speciose group. The use of smaller home ranges post-harvest may reflect smaller colony sizes and lower roost availability, both of which may increase isolation of colonies and vulnerability to local extinction