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University of California Publications in Geology [Vol.9 



not seem to be so large a ratio as is shown by the fossil remains. 

 Does the ratio displayed in the collection of remains represent the 

 true faunal relation of these two groups at the time of deposition? 



Were we to assume that the proportion of owls to hawks at the 

 present time represents the true condition of affairs at the time the 

 asphalt deposits were forming, it would be necessary to concede that 

 owls were for some reason less positively attracted to the theatre of 

 action at Rancho La Brea than were the hawks and eagles. Does the 

 owl less often feed upon dead or disabled prey? Does it less com- 

 monly alight in hunting and therefore escape the asphalt trap? 



During several years' acquaintance with the Rancho La Brea 

 region, the present writer has been much interested to watch the 

 Recent outflows of crude oil for the operation of the trap as it is set 

 today. Conditions prevail there at the present time which must 

 approximate somewhat closely, except for magnitude, the conditions 

 in Pleistocene time. In the Recent outpourings of raw asphalt the fol- 

 lowing species of birds have been noted still in the flesh : 



These observations, so far as they are of value, go to show that 

 owls are among the most common victims of the asphalt and hawks 

 among the least. Certainly it would seem that the region is not 

 unattractive to owls. 



Dr. Joseph Grinnell, Director of the California Museum of Verte- 

 brate Zoology, in an informal conversation on the matter expressed an 

 opinion, the recording of which he has kindly permitted. In brief it is 

 this : Owls hunt by sound instead of by sight. The whole specialization 

 of the bird through enlargement of the auditory apparatus to receive 

 the slightest sound and the softening of the plumage to prevent con- 

 fusion by whirring flight, points to the dependence of the bird upon the 

 slightest noise made by the prey. Hence, unlike the hawk who hunts by 



Individuals 



Barn owl, Aluco pratincola (Bonaparte) 



Night heron, Nycticorax nicticorax (Linnaeus) 

 Green heron, Butorides virescens (Linnaeus) .. 



Meadow lark, Stumella veglecta Audubon 



Shore bird (indeterminate) 



Turtle dove, Zenaidura macroura (Linnaeus) . 



Pigeon, Columba livia Domestic 



Peregrine falcon, Falco peregrinus Tunstall ... 



Night hawk, Chordeiles, sp 



Linnet, Carpodacus mexicanus (Muller) 



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