798 



THE NATURE BOOK 



fur partly by the thumb and foot claws, 

 and partly by the milk teeth, whose re- 

 curved and often bifurcated points are 

 singularly well adapted for the purpose. 

 The infant Bat is blind and practically 

 naked, while immature Bats of the year 

 are usually markedly different in colour 

 from Hats of the previous generation. It 

 is probable that from, say, May to August 

 the females congregate apart from the 

 mak^s so as to have the control of their 

 family affairs undisturbed, but, during 

 hibernation. Bats 

 of both se.xes, and 

 often of several 

 different species, 

 may be found by 

 the score in suit- 

 able retreats — 

 caves, ruins, hol- 

 low trees, and so 

 forth. 



The duration 

 and profundity of 

 their winter sleep 

 is dependent on 

 the temperature of 

 their immediate 

 surroundings, and 

 if. as seems likely, 

 the crowding of 

 Bats during hi- 

 bernation m a i n - 

 tains this tempera- 

 ture at such a 

 height as to pre- 

 vent complete torpidity, their jostlings, 

 changes of position, and, as Millais hap- 

 pily puts it, " seething." may be easily 

 accounted for. The Xoctule, Serotine, 

 Pipistrelle and Long Eared Bat may- 

 be considered " light " sleepers. The fact 

 that a hibernating Bat, or a Bat that 

 has been reduced to a comatose state 

 by the vagaries of our English sum- 

 mer, feels damp as well as cold may, 

 perhaps, be due to the numerous 

 secreting glands on a Bat's body. 

 To such must certainly be attributed 

 the singularly noisome odour which 

 several oi our Bats, notably the Xoctule 

 and the Serotine, diffuse at random. 



All British Bats are insectivorous, 

 and not only the character of their flight — 

 which, be it noted, is a most difficult 

 and uncertain criterion f(;r distinguishing 



FORE-LIMB (X f) AND SKULL i NATURAL SIZE) 

 OF LONG-EARED BAT 



\. Collar bone (clavicle). 



2. Shoulder blade (scapula). 



3. I'pper arm bone (humerus). 



4. Fore-arm bone (radius) ; the ulna is merely a splint. 

 D 1. Thumb (pollex). D 2, 3, 4, 5. FinSers. 



The thinness of the bones composing the skull can be 

 judged from the fact that the roots of the teeth in the 

 upper jaw can be seen through them. 



the species — but also the heights to which 

 they ascend, and the localities which 

 they affect, are determined by the flight 

 and distribution of the insects on which 

 they are feeding. I have watched 

 Noctules hawking a hundred feet up 

 where it was impossible to determine 

 with a glass what they were after, and 

 I have seen more than twenty of them 

 together not more than twenty feet from 

 the ground, engaged in annihilating a 

 brood of the smaller stag-beetle {D. 

 parallflopipcdiis) 

 whose first experi- 

 ence of a free-fly- 

 ing existence was 

 terminated almost 

 before they had 

 quitted the de- 

 c a }• e d w a 1 n u t 

 trunk which for 

 some years had 

 provided them 

 with fond and 

 shelter. 



Although 1 

 watched this epi- 

 sode with keen 

 attention, was 



unable to detect a 

 single instance of 

 a Bat "pouching" 

 its victim. More 

 than one observer 

 has descril)ed a 

 m a n oe u V r e by 

 which ca])tive Bats make use of their 

 interfemoral (tail) membrane in order to 

 secure a hold of a refractory moth or 

 beetle, and one would have thout;ht tiiat 

 a beetle of the size of D. parallc/opipcJus 

 would have necessitated some such ex- 

 pedient. 



As it was, however, the Bats seemed per- 

 fectly satisfied with two or three sharp and 

 audible crunches, after which they allowed 

 what was left over to drop from their 

 mouths. The ground beneath them was 

 strewn with legs, wing-cases, and insect 

 remnants generally. Occasionally a 

 whole beetle w^ould come down, and two 

 or three of those which I picked had 

 been practically bitten in half. It is, 

 of course, possible that an oiibarras des 

 richcsscs had in this case disturbed the 

 normal order, l^ut I am inclined to think 



