NO. 7 PROTECTIVE ADAPTATIONS McATEE I33 



Let US now take up sonic of tlic groups of interest in the order of 

 their appearance in the tabulation. From the large number (274) 

 of records for shrews it would appear certain that the alleged special 

 defenses of these animals are no protection against birds. Thirteen 

 species of shrews were identified in the stomachs ; 27 species of birds 

 are known to prey upon our common short-tailed shrew and 23 upon 

 unidentified species of Sorex. Shrews are by no means gregarious, 

 nevertheless five specimens of Sorcx personatus were taken at a meal 

 by a great gray owl. Considering their almost exclusively under- 

 ground life, moles were captured fully as often as would be expected ; 

 the number of species of birds preying upon them is 12. 



Bats, again on account of their nocturnal activity, are not greatly 

 exposed to the attacks of birds. Six predators upon them are recorded 

 in our tabulation with a total of 19 identifications. While the Mus- 

 telidae are provided with unusually strong musky scents, they are also 

 rather above the size for many birds to attack. The single determina- 

 tion in our table, attributed to a crow, might perhaps be more correctly 

 added to the records of carrion. Skunks, of this family, customarily 

 cited as examples of animals having noxious qualities and warning 

 coloration to advertise them certainly are too large for all except a 

 very few species of our raptors to conquer. However there are a 

 number of published and other records of the great horned owl 

 preying upon skunks. 



Muridae (mice and rats) are secretive, elusive animals with what 

 would be called highly protective coloration, but this does not prevent 

 their being the staple mammal food of birds. Meadow mice, perhaps 

 our most ubiquitous rodents, are eaten by the largest number of 

 species of birds, namely 44. Twenty-six species of birds are known 

 to feed on the house mouse and 35 upon deer mice {Peromyscus). 

 We have records of five species of birds preying upon our largest 

 member of this family, the muskrat, and eight upon the smallest 

 (Rcithrodontomys) . 



Pocket gophers, like the moles, spend most of their lives under- 

 ground and this fact limits the opportunities of birds for capturing 

 them, yet there are 31 records for 11 species of birds; nocturnal and 

 burrowing habits shield also the pocket mice and kangaroo-rats. 

 Captures in these groups probably are in proportion to their reduced 

 availability. Jumping mice (14 records), a more diurnal group, seem 

 to be proportionately represented. 



Erithizontidae (porcupines) are entirely beyond the size of prey 

 practicable for birds, though possibly some of them are captured 



