408 THE OWLS 



the fact that some did not is fraught with deep significance, throwing 

 an unexpected light on that most difficult of problems, the migratory 

 instinct. This must undoubtedly have been deficient in a certain 

 percentage of these birds, and this, too, although the species is an 

 eminently migratory one. "Lemming years" in Scandinavia are 

 attended with a similar increase in the number of this owl. But 

 though we seem to have no records dealing with the point, it seems 

 probable that this increase is not attended with a similar mortality, 

 since the venue of the plague slowly changes and is extended over a 

 large area. The owls follow their food. Since, however, the ultimate 

 destination of these migrating hosts is said to be the sea, all participat- 

 ing in this tremendous inarch ultimately perishing, there must, when 

 this consummation takes place, be a similar elimination of the birds 

 w r ith the non-migratory instinct. On this head, however, no observa- 

 tions appear to have been made. 



Small mammals do not, however, constitute the only food of the 

 shorteared-owl, for I myself have frequently found numbers of the 

 common dorbeetle (Geotrupes vernalw) in the crop and gizzard of these 

 birds, and bats, reptiles, and fish are also included in its dietary. 



Of the habits of the shorteared-owl prior to mating nothing seems 

 to be known. In their manner of nesting, as we have already hinted, 

 they differ conspicuously from the nearly related longeared-owl ; 

 haunting, as we have already seen, treeless areas, they breed, as might 

 be supposed, like the snowy-owl, upon the ground. Nest-building 

 may be, and often is, dispensed with altogether, the eggs being laid in 

 a depression in the ground, generally ready-made. But the Rev. 

 F. C. R. Jourdain tells me that he has found that in sandy soils the 

 bird scratches a hollow for herself. Sometimes two or three may be 

 found close together perhaps representing more than one year's 

 nesting-place. But it is instructive to notice that this hollow may 

 be lined with grass, or dry, broken leaves of sedges, and occasionally 

 a feather or two. Seebohm, when on an egg-hunting raid in the 

 Norfolk Broads district, had the good fortune to examine the nests 



