NOCTULE AND PIPISTRELLE BATS
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get " under control " immediately it opens its wings. It swoops downwards with beating wings for a yard or two and then upwards or horizontally away. Even on warm nights and after a short time in the net we found them loath to take wing when the net was held low, with the top ring from which they hung 2 ' 6" to 3' from the ground. If it was raised to 4 ' to 4 ' 6" they quickly flew away. When they took flight from the lower level the invariable drop towards the ground before they were in fĂźll control brought them very close to it and and on a few occasions a bat actually landed on the ground before it could get into fĂźll flight. It seems probable that it was proximity to the ground which made them loath to take flight when the net was held low. The only other bats we caught were pipistrelles (P. pipistrellus). These we usually released as soon as they were caught, merely opening the hand in which they were held. They took flight at once from the open palm, Aying upwards almost like a helicopter. Hanging from a finger, as the noctules hung from the top ring of the keep-net, a pipistrelle seems to fly straight off with no marked drop toward the ground. If thrown into the air a pipistrelle seems to be in complete control immediately it opens its wings : once these Start to beat the bat remains at the same level, with no fall toward the ground. Occasionally we put a pipistrelle or two in the keep-net to take home and examine. Whether or not there were noctules in the net as well, the pipistrelles were very active, Aying from side to side across the narrow expanse, scarcely wider than a pipistrelle's wingspread of 7 to 8 inches. The difference between the take off Aight of the two species is therefore very marked. A pipistrelle with a weight of about 4 to 5 grammes, relatively broad wings and a wingspread of 7" or 8" has much more control at low speeds than a noctule with a weight of about 30 grammes, narrow wings and a wingspread of 14" or 15 ". T h e reverse of course is obvious when the two species are seen Aying together, the rapid dashing flight of a noctule is in marked contrast with the normal slow twisting one of a pipistrelle.