I attended my first bat survey on a drizzly wet wednesday night of this week (July 4th), in Platt Fields Park, Manchester. I loved it.
Tagging along with the South Lancashire Bat Group, of which I have recently become a member, the main aim of the outing was to try and locate the presumably close roosting location of Noctules (one of 10 bat species native to the region) that were recently found to feed at the site.
Our party was split into 3 groups, each situated at opposing ends of a large lake, in order to determine the location from which the bats travel. Each group was armed with torches, site maps, survey forms and heterodyne bat detectors. Conversely, heterodyne bat detectors work by transforming the inaudible (to humans) echolocation sounds emitted by bats into a frequency that our ears can detect. The resulting soundtrack can be used (by experienced ears) to identify bats to genus and even species level.
After an uneventful half hour, my bat detector, tuned in to 45kHz, suddenly clicked into action, emitting a rapid bubbly, clacking noise. This I was informed, was the call of a Common Pipistrelle, and sure enough a few seconds later a small bat swooped past me towards the lake. Soon after, my colleagues detector, tuned to detect Noctule’s, (~22kHz) also sprung to life with a slower wooden ‘clacky’ noise dispersed with high pitched chirrups.
Within minutes the detectors were relaying a mosaic of sounds. An occasional velcro like sound, I was told was the sound emitted when a bat caught its prey, other noises represented social calls, and re-tuning the detectors indicated the presence of additional bat species from the genus Myotis.
The visual display that accompanied the live soundtrack was equally impressive. Bats flying within meters of my person were swooping, diving and skimming across the lake for food whilst others were chasing each other in play. I was informed that in addition to each bats characteristic echolocation, its flying habits are a further means by which to identify its species.
After an hour or so of this display, our observations indicated 2 locations from which the Noctule’s were likely arriving and with it being dark and wet we decided to call it a day. Future studies in daylight will seek to confirm bat roosts in the predicted locations.
I will be doing another survey with the bat group next week and probably many more over the summer. Im looking forward to attending surveys that involve handling the animals as I have never had the opportunity to do this. In the meantime I need to familiarise myself with local bat ecology and also begin learning each species echolocation and defining physical characteristics.