OBSERVATIONS ON THE NOCTULE. 58 



The time at which the first Bat issued from the hole varied 

 from twenty-eight minutes after sunset, on April 21st, to seven 

 minutes before sunset, on Aug. 14th. The Bats leave the den in 

 rapid succession — on Aug. 27th twenty-two emerged within a 

 minute — but their return is much less regular. This is probably 

 due to the varied success of individuals in obtaining food. During 

 August and September, at any rate, on fine still evenings, the 

 duration of the vespertinal flight is sometimes less than an 

 hour ; on Aug. 27th a Bat entered the den fift^^-five minutes, and 

 on Sept. 4th fifty-seven minutes, after the first had emerged. On 

 each evening, however, the flight in some cases lasted at least an 

 hour and a half; and on Sept, 5th some of the Bats were absent 

 for more than two hours. It is probable that on wet and windy 

 evenings the duration of the flight is even less than an hour, but 

 I have no data to prove this. It is easy to count the Bats as they 

 leave their den in the twilight, but a difficult matter to make sure 

 of the number that return. They do not often enter the hole 

 immediately on their arrival, but dash round and among the trees, 

 and in many cases pitch several times for an instant on the tree- 

 trunk near the hole. Their advent is proclaimed by the beating 

 of their wings, but even on moonlight nights all that one sees is 

 a form silhouetted for an instant against a patch of sky. When 

 the Bat is flying against a background of tree-trunks or foliage 

 one can see nothing. It is true that aiaint rustle may be heard 

 when a Bat actually enters the hole, but this resembles the noise 

 made when it pitches for an instant on the tree-trunk, and if two 

 or more Bats arrive together, as often happens, the confusion is 

 increased. A good deal of intermittent squeaking may be heard 

 in the den after the arrival of the second Bat. The following 

 extracts from my note-book describe the course of events on 

 three evenings : — 



Sept. '6rd. — Fine moonlight evening; no wind. First Bat 

 emerged at 7 7, followed by twenty-six others before 7.11. Much 

 squeaking for half an hour before they appeared. None seen or 

 heard until 8.S.2, when one returned and entered the hole, after 



1898, I saw several flying above the Beaver's Pool, on the Conway, near 

 Bettws-y-Coed. la August, 1895, Mr. T. A. Coward saw many at Nevin, 

 Carnarv- nshire. The Bats, which were flying low over the fields at the 

 edge of the cliffs, appeared to be feeding on the winged males of a black ant. 



