A REVISION OF THE FORMS OF THE GREAT BLUE HERON 

 (ARDEA HERODIAS LINNiEUS). 



By Harry C^. Oberholser, 



Of the Biological Survey, United States Department of Agriculture. 



Large birds, as a rule, do not seem to prove generally attractive to 

 the modern systematic reviser, chiefly because of the usual difficulty 

 of gathering together a satisfactory series, and of handling the mate- 

 rial in making comparisons. The great blue heron, Ardea herodias 

 Linmeus, like many other large species of North American birds, has 

 been in much need of careful systematic study, and the results m the 

 following })ages are ofl'ered as an attempt at such revision. Previous 

 literature bearing on the subject is confined to descriptions of new 

 forms, and to other short ]:)apers. Like the writer's recent review of 

 Butondes virescens and its races,^ the present paper was undertaken 

 at the suggestion of, Mr. H. W. Henshaw, chief of the Biological Sur- 

 vey, as an aid in working out the ranges of the forms of this species for 

 a forthcoming bulletui by the Biological Survey on the distribution 

 and migration of the North American herons. 



Notwithstanding the difficulty of obtaining material, it has been 

 possible to examine altogether 221 specimens of Ardea herodias, 

 including the types of all its valid races except t:wo, Ardea herodias 

 herodias and Ardea. herodias lessonii. This material comprises the 

 entire collections of the United States National Museum, with that of 

 the Biological Survey; the American Museum of Natural History; 

 the Academy of Natural Sciences of Philadelphia, with those of 

 Mr. Witmer Stone and AIi*. H. W. Fowler; the collection of Dr. Jona- 

 than Dwaght, jr.; also a number of specimens from the Museum of 

 Comparative Zoology at Cambridge, Massachusetts; from Messrs. 

 A. E. and O. Bangs; the Field Museum, of Chicago; Mr. John E. 

 Thayer; and Mr. Edward A. Preble. In addition, Mr. Joseph Grin- 

 nell very Idndly made some comparisons of specimens in the Museum 

 of Vertebrate Zoology of the University of California, also sent meas- 

 urements of a number of specimens; and Mr. G. Willett has furnished 

 information concerning the occurrence of the species on the Santa 



' Proc. U. S. Nat. Mus., vol. 42, 1912, pp. 529-576. 



Proceedings U. S. National Museum, Vol. 43— No. 1939. 



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