Identify Vespertilionid Bat Calls

Vespertilionid bat calls are very brief (usually less than 10 msec), but emitted in a rapid series with up to 25 calls per second. Each call will be heard as a short ‘click’, but may be prolonged into a slightly longer ‘tock’ or a much longer ‘slap’. Very quiet or distant calls may appear to be very quiet ‘ticks’.