180 LIFE-HISTORIES OF BIRDS 



cloudy weather, it moves with greater freedom and confi- 

 dence. There seems to be a better adaptation upon the part 

 of young birds, to the intense light of day, than upon the 

 parental part. May it not be that the constant habit of 

 sleeping during the day, consequent upon a full night's 

 carousal, has so weakened the organs of sight as to render 

 them ill-adapted to the strong sunlight ? Animals, that arc 

 accustomed to labor while it is day, suffer considerable in- 

 convenience for a while when compelled to adopt night-toil. 

 Again, if necessitated to come back to day-labor, the force 

 of habit again manifests itself, and a like inconvenience, 

 though probably in a less degree, is xperienced. The iricles 

 undoubtedly habituate themselves to this reversal of habit. 

 The fact that the young of Bubo virginianus can adapt 

 themselves to the intense light of the sun almost equally 

 with the Eagle although being mainly nocturnal in hab- 

 its, by the voluntary rather than automatic movements of 

 the iris, associated with the already mentioned circumstance 

 in the history of the present species, strongly favors the hy- 

 pothesis that all our Strigidce can in time adapt themselves 

 to a change of habit pari passu with visual modification. 

 The Day Owl is a noted example of a species that is pre-emi- 

 nently diurnal, which has undoubtedly evolved from a spe- 

 cies that was primitively nocturnal. 



The flight of this Owl is noiseless and gliding, and so still 

 as to be scarcely perceptible. While it spends much of its 

 time veering through the atmosphere in quest of the nocturnal 

 insects which contribute largely to its diet, it does not deem 

 itself too aerial to descend to the earth when it can subserve 

 its purposes. Like the Barn Owl, it is a great lover of low 

 meadows, and even the premises adjoining the barn, where 

 it makes terrible havoc among the small quadrupeds that 

 enjov such retreats. Sailing noiselessly over the tall grasses, 

 with the keenest vision it will readily descry the smallest 

 creature that moves, and in the twinkling of an eye will 

 pounce upon its victim and bear it away transfixed with its 



