274 CALIFORNIA ACADEMY OF SCIENCES. 



of color modification. The adults are generally exactly- 

 alike in color and the young frequently do not differ 

 greatly from them, but are sometimes distinctly barred 

 instead of mottled. Brown, gray, and white are the 

 usual colors, together with some buffy, tawny or ochrace- 

 ous. The genus Megascops is peculiarly susceptible to 

 the direct influence of the environment, and as has been 

 already mentioned under the head of geographical dis- 

 tribution, breaks up into a great variety of forms in dif- 

 ferent parts of the country. The Bubo virginianus group 

 is also interesting from the manner in which it becomes 

 pale toward the Arctics, being almost pure white at the 

 northern limit of its range. The general mottled ap- 

 pearance of most owls blends very well with the tree 

 trunks, and they are thus protected during the day at 

 which time they are so comparatively helpless when 

 attacked. The color of the burrowing owl (Speotyto 

 cunicularia hypogcea) blends very well with the ground 

 of the fields in which it is generally found, and its white 

 throat has already been mentioned as a socialistic mark- 

 ing which would be useful in the darkness of its bur- 

 row. 



ORDER PSITTACI. THE PARROTS, MA- 

 CAWS, PAROQUETS, ETC. 



FAMILY PSITTACIDtE. Parrots. 



Like the pigeons, this cosmopolitan and long estab- 

 lished group should be considered as a whole in attempt- 

 ing to arrive at any conclusions with regard to the 

 evolution of the colors. These birds are eminently 

 denizens of the tropics, and their colors have all the 

 diversity and brilliancy which we naturally associate 

 with that region. The green colors are probably in the 

 main protective in their nature, blending with the leaves, 



