Nature Near London: River Thames Bat Walk, Monday July 15th, 2013

In order to measure the results of our project work in Richmond, Kingston and Hounslow, it is necessary to be able to survey sites for species that it is hoped will benefit from the creation of habitat or the reintroduction of certain management regimes. One animal that is an important indicator is the bat. We're blessed in Richmond that 55 percent of the land area is open space, compared with a mere 12 percent in Kingston, while Hounslow claims to have the "highest percentage of green areas of all London boroughs" (http://www.hounslow.gov.uk/index/leisure_and_culture/parks_and_open_spaces.htm). All this open space, together with continuous mature tree lines along our rivers are important for bat foraging and roosting.
Our guide and trainer for the evening was renowned local bat expert, Alison Fure, who has an encyclopaedic knowledge of these fascinating creatures. The group met on the Hampton Wick side of Kingston Bridge and were issued with the all-important bat detectors. After a short introduction about the use of the detectors and what we might be able to detect, we started off along Barge Walk in the direction of Hampton Court Palace.
After walking for some time, without detecting anything other than bush crickets at 30 kHz, the light was quickly fading as we approached the outlet tunnel from the famous filter beds at Seething Wells on the Surrey bank. This is a prime site for bats, and so it was that the first bats we detected were Daubenton's emerging from the tunnel. Now it was pretty dark, particularly away from the light pollution of central Kingston, and it wasn't long before bats were all around. Within no time at all, we'd detected six species, including Common pipestrelle, Soprano pipestrelle, Nathusias's pipestrelle, and the rather rare Leisler's and Natterer's, as well as Daubenton's feeding over the water. Occasionally, Alison would shout "20", which was our instruction to turn our bat detectors to the frequency where we might detect Leisler's or perhaps Nocutule bats, but being novices we were usually too slow and the bat had gone.
It's easy to forget the time as one focuses on trying to distinguish between the different species according to their ultrasonic behaviour, and so within no time at all we needed to head back to Kingston Bridge, detecting as we went. By now bats were foraging on insects all along the towpath.
By the time we got back to Kingston it was late, but everyone had enjoyed a fascinating evening. Strangely, joining a bat walk is perhaps one of the few occasions when you would choose to venture along the banks of the Thames at night.
Now, hopefully we feel better equipped to try and survey bats at other sites across the three boroughs, to help us understand how our work can benefit different species.