SMALLER MAMMALS OF NORTH AMERICA 



60^ 



malaria from infested areas. One or more bat 

 houses have been built at San Antonio, Texas, 

 for the purpose of assembling bats in large 

 numbers, and many untenable claims have been 

 put forth concerning the benefit to be derived 

 from their services. The Mexican bat is the 

 species which abounds above all others at San 

 Antonio and is the principal species which has 

 occupied the bat houses near town. It is def- 

 initely known that bats often fly miles from 

 their roosts wdien feeding and do not concen- 

 trate on any one kind of insect. Examination 

 of the contents of the stomachs of Mexican bats 

 shows that they feed on beetles and numerous 

 other insects, but rarely upon mosquitoes. I 

 have visited many Mexican towns and villages 

 in which every house was haunted by numbers 

 of these bats and where malaria was perennial. 

 The evidence against these animals serving any 

 useful purpose in checking malaria is con- 

 clusive. 



It may be repeated here, however, that all 

 of our bats are of high utility as insect-destroy- 

 ers and should be protected. Among the many 

 species of varying habits which exist in the 

 United States, a few make their homes about 

 houses in annoying numbers. In place of killing 

 them to abate the nuisance, it would be better 

 to exclude them from buildings by closing the 

 entrance ways promptly after all have left in 

 the evening, and thus by quiet eviction cause 

 tliem to find abiding places elsewhere. The 

 destruction of forests, and the consequent ab- 

 sence of the hollow trees where they formerly 

 lived, is mainly responsible for bats and chim- 

 ney swifts coming- to houses for harbor. 



THE BIG-EARED DESERT BAT (An- 



trozous pallidas and its relatives) 



{For illustration, see page 567) 



The marvelous variations in structure of the 

 ears and other organs about the heads of insect- 

 eating bats serve probably as microphones by 

 which the flight of their prey may be detected 

 and its direction located with instantaneous 

 certainty. The beautiful accuracy with which 

 this hearing mechanism works must be evident 

 to any one who will take a position where he 

 may have the evening glow of the western sky 

 as a background for flights of bats. It is cer- 

 tain that the small and ineffective eyes these 

 animals possess could never locate their minute 

 flying game and enable them to secure it in 

 the whirling, zigzag courses they pursue, often 

 at a speed and under a control which few, if 

 any, birds could rival. 



The great ears of the big-eared desert bats 

 illustrate one form of a highly developed hear- 

 ing apparatus and give these animals a hand- 

 some and strikingly picturesque appearance. 

 This character at once distinguishes them from 

 others of their kind in the United States. 



The distribution of this species lies mainly in 

 the arid parts of the Southwestern States and 

 Afexico. It extends from western Texas, south- 

 ern Colorado, Nevada, and Oregon, south to 



Queretaro, on the Mexican table-land, and to 

 the southern end of the peninsula of Lower 

 California. The vertical distribution extends 

 from sea-level up to at least 5,000 feet altitude. 

 By day these desert bats live in crevices and 

 caves in cliffs, in old mining tunnels, hollows 

 in trees, and in sheltered places about the roofs 

 and walls of houses, barns, or other buildings. 

 Their presence in dark hiding places may some- 

 times be detected by occasional grating squeaks. 

 They appear to lack any musky odor which 

 characterizes so many bats. About the ist of 

 June each year either one or two young are 

 born, and for a time these cling to the mother's 

 breast and are carried during her swift flights 

 in pursuit of insect prey. 



Often when camping at desert waterholes, I 

 have seen them come in just before dark to 

 drink, scooping up water from the surface 

 while in flight, and then circling back and forth 

 over the damp ground at an elevation of a few 

 yards for the capture of some of the insects 

 common in such places. At such times, with 

 the distant hills mantled with a deepening 

 purple haze and the pulsating heat of the day 

 replaced by the milder temperature of approach- 

 ing night, these bats could often be seen sharply 

 outlined against the rich orange afterglow of 

 the departed sun. Here and there in the still 

 air flickered and zigzagged multitudes of tiny 

 bats, like black butterflies, and among them the 

 occasional big-eared bats on broad wings ap- 

 peared huge in contrast. Their wing strokes 

 were slower and shorter than those of the 

 smaller species and impelled them forward in 

 a swift, gliding movement which gave their 

 evolutions a sweeping grace beautiful to see. 

 In August several years ago, during a visit 

 to the Indian School at Tuba, in the Painted 

 Desert of northern Arizona, I found these bats 

 living in considerable numbers about the build- 

 ings. Just before dark they swarmed out and 

 hunted about the surrounding orchards and 

 small fields. One evening my collector shot 

 at one as it circled over a potato field in a small 

 orchard. It continued its flight, circling low 

 among tlie apple trees as though unhurt, when 

 suddenly it dropped to the ground. Supposing 

 the bat to be wounded, it was cautiously ap- 

 proached and covered with a hat, when, with- 

 out a struggle, it permitted itself to be picked 

 up by the nape. It then became evident that 

 the bat was imhurt from the shot. The reason 

 for its sudden descent was revealed in the per- 

 son of a large, fat mole cricket (Stciwpahnatiis 

 fuscus) which it was holding firmly in its jaws, 

 and so ferociously intent was it in biting and 

 worrying its luscious prey that it paid not the 

 slightest attention to its captor. Finally it was. 

 killed by having its chest compressed and died' 

 with its bull-dog grip on its prey unbroken. 



These bats, like the other members of the- 

 tribe in the United States, are fully as bene- 

 ficial to the farmer as the best of our insect- 

 eating birds and deserve equal protection in 

 place of the general persecution from which 

 they now suffer. 



