From Ian Rabjohns
You report on bats intentionally jamming each other’s sonar when several are feeding in the same locality (15 November, p 16). While recording bat species in the Wye valley area near south Wales I regularly picked up several common pipistrelles (Pipistrellus pipistrellus) feeding together.
Each individual made a slight shift in frequency from the standard 47 kHz. Every now and then I would get what I termed the “sod off” call – a very loud broadband “shout” covering the whole frequency range and much more at either end.
I always presumed that this was to discourage the opposition from coming too close to the bat concerned or to its prospective meal. It would also interfere with the reception of any other bat nearby; it certainly gave me a shock if I was close enough and wearing headphones.
Penallt, Monmouthshire, UK
