UNIVERSITY OF CALIFORNIA PUBLICATIONS 



BULLETIN OF THE DEPARTMENT OF 



GEOLOGY 



Vol. 9, No. 8, pp. 97-104, 1 text figure Issued January 18, 1916 



THE OWL REMAINS FROM RANCHO LA BREA 



BY 



LOYE HOLMES MILLER : I 



CONTENTS 



PAGE 



Introduction 97 



Record of Species 99 



Aluco pratincola (Bonaparte) 99 



Otus asio (Linnaeus) 100 



Bubo virginianus (Gmelin) 100 



Asio 102 



Speotyto cunicularia (Molina) 104 



Summary 104 



INTRODUCTION 



These nocturnal birds of prey appear, for some reason, much less 

 commonly in the asphalt beds than do those generally distinguished 

 as diurnal hunters, the Accipitres. This difference is notable both in 

 point of numbers and in variety. Whereas the great group of hawks 

 and eagles makes up full fifty per cent of the whole mass of bird 

 material taken from these beds, the owls represent no more than five 

 per cent. Twelve species of accipitrines have thus far been deter- 

 mined from the mass, while many yet remain unidentified. On the 

 other hand, but six species of owls are to be distinguished in the same 

 collection. We thus have a preponderance of ten to one in numbers 

 and of more than two to one in species in favor of the diurnal birds 

 of prey. 



At the present time we might expect to find, at most, sixteen 

 accipitrines in the southern California region, while as many as eight 

 species of owls are recorded from the same locality, a ratio of two 

 to one. In point of numbers it would be difficult to make an 

 accurate estimate of the living population, though it would certainly 



