Nyctalus noctula is one of the largest bats in Europe (Petit & Mayer, 1999). It has long, narrow wings and short fur. The dorsal side is a reddish-brown colour whilst the ventral side is a duller, lighter brown. Juveniles are darker than adults, and appear pale brown on the dorsal side. The wing membrane, nose and ears are blackish-brown. Noctule bats are relatively common throughout most of England and Wales but are now scarce in areas of intensive agriculture, owing to the increased usage of pesticides and hedgerow removal. The noctule uses two main calls for echolocation. The frequencies of the first are 26-47 kHz, have most energy at 27 kHz and an average duration of 11.5ms. The frequency of the second call is 22-33 kHz, having most energy at 22 kHz and an average duration of 13.8ms (Parsons & Jones, 2000); (Obrist et al, 2004).
Nyctalus noctula favours open habitats (Petit & Mayer, 1999) and is found in woodland, parks, wetlands, pasture land and large gardens. Summer roosts have also been found in bat boxes, hollow streetlights and under bridges. Hibernation takes place in hollow trees, rock crevices and buildings (Schober & Grimmberger, 1989). Noctules emerge early, occasionally even before sunset, and so you are very likely to see them in summer as they swoop from tree height to catch midges, moths, mayflies and other tiny insects in the air. Occasionally, and mostly after midsummer, noctule bats take beetles (mainly chafer and dung beetles), and other quite large insects from the ground. They are fast fliers, capable of reaching 50 kilometres per hour.
- Petit, E. & Mayer, F. 1999. Male dispersal in the noctule bat (Nyctalus noctula): where are the limits?. Proceedings of the Royal Society of London, 266: 1717 – 1722.
- Parsons, S. & Jones, G.2000. Acoustic identification of twelve species of echolocating bat by discriminant function analysis and artificial neural networks. J Exp Biol., 203: 2641-2656.
- Obrist, M.K., Boesch, R. & Flückiger, P.F. 2004. Variability in echolocation call design of 26 Swiss bat species: Consequences, limits and options for automated field identification with a synergic pattern recognition approach. Mammalia., 68 (4): 307-32.
- Schober W. & Grimmberger, E. 1989. A guide to the bats of Britain and Europe. Hamlyn, London.
Compiled by David Mallaburn