1916] Miller: Oivl Remains from Rancho La Brea 



!>!) 



sight, the owl would not be tempted to so great an extent by the asphalt 

 victim. This aspect of the question is probably a very important one, 

 although some evidence may be noted running counter to it. Captive 

 owls are fed quite as readily upon non-living food as are the hawks, 

 even when the food bears no optical resemblance to the natural prey. 

 Owls also will alight upon mouse-baited steel traps set for carnivores ; 

 thus we have the suggestion that sound is only one factor in the dis- 

 covery and selection of the prey and the supposed difference in the 

 carrion habit of the hawks and the owls is reduced materially as a 

 factor in the prime question. 



Exposure of fresh asphalt was doubtless in more extensive masses 

 during the Pleistocene than at the present time, else it had been 

 impossible to entangle the large animals whose remains occur in these 

 beds. Such conditions would have increased the proportion of large 

 hawks and eagles in the catch and at the same time perhaps reduced 

 the number of small hawks and especially of owls, since in the larger 

 mass of asphalt, small prey captured during the day when the asphalt 

 was most plastic would have entirely disappeared before nightfall. 

 Under such circumstances the bait would be removed from the trap 

 before the twilight hunting-time of the owls arrived. It is a very 

 notable fact that the hawks and falcons are far outnumbered in the 

 asphalt collections by the much larger eagles. It is so hard to con- 

 cede a living fauna of such proportions that an effort to find some other 

 expanation is natural. While the number and variety of the eagles 

 was undoubtedly greater during this age of mammals, it seems prob- 

 able also that the larger size of the asphalt outpours and the consequent 

 rapid disappearance of the smaller raptor bait may have had some 

 influence upon the results and that the conclusions naturally drawn 

 from a study of the fossil remains would better be modified in regard 

 to the proportions of the various elements of the fauna. 



RECORD OF SPECIES 

 ALUCO PEATINCOLA (Bonaparte) 



This form is by far the most common of the entire group of Striges 

 in the Rancho La Brea deposits. The remains occur at all depths 

 and embrace all characteristic parts of the skeleton so that very 

 accurate determination of the species is made possible. Careful study 

 of this series of specimens fails to bring to light any variation outside 

 that natural to the species as it lives in the region to-day. 



