98 BULLETIN 135, UNITED STATES NATIONAL MUSEUM 



blue nestlings lived on Buchanan and Barnes Keys; 20 on the Cape Sable 

 group. Among the adult birds was shown the same tendency of the great whites 

 to predominate on the lower Keys, and of the big blues to be more numerous on 

 the upper. Of the 40 nests examined, 3 held mixed broods of white and blue 

 birds in the ratio of 2:1, 2:2, and 2:1. The first had a blue parent, the second a 

 white parent; the parent of the last was not seen. The mixed broods were found 

 on Buchanan and Barnes Keys, but all the adult blues, collected on any of the 

 keys, showed admixtures of white blood. 



It has been stated that the great white heron and the Ward heron 

 are exactly alike in form, size and proportions, the only difference 

 being in color. This generally accepted statement has strengthened 

 the theory that they are merely color phases of one species. Mr. 

 Holt has made a careful study and comparison of 24 great white 

 herons, 24 Ward herons, and 10 Wiirdemann herons, all breeding 

 adults, whicli throws considerable new light on this subject. He finds 

 that a "noticeable feature of the white birds is the great reduction, 

 often total absence, of the occipital plumes. Only 9 of the 24 birds 

 have plumes over 100 millimeters in length, whereas more than half 

 have no plumes at all. These plumes, when present; are wide at the 

 base and taper to a fine point — a form perhaps best described as long 

 acuminate — lanceolate — and are quite different from the two long ligu- 

 late occipital plumes of Ardea herodias wardi.^^ Referring to his 

 tables of measurements we find that the average length of these 

 plumes in 24 specimens of occidentalis is 97.3 millimeters, the longest in 

 any individual being 192 millimeters; the average length in 24 spec- 

 imens of wardi is 177.8 millimeters, the longest in any individual 

 being 230 millimeters ; this leaves an average difference between the 

 two species of 80.5 millimeters, or more than 3 inches. 



The scapular and jugular plumes of the great white also show a tendency to 

 reduction, when compared with similar structures of Ward's heron. 



A small but distinct difference between occidentalis and wardi in absolute and 

 proportionate size of bill is indicated by the measurements of the six fully adult 

 occidentalis in hand, when compared with similar measurements tabulated by 

 Oberholser (1912) for six entirely comparable Florida specimens of wardi. The 

 average lengths of wing, tail, and tarsus in this series are greater for wardi than 

 for occidentalis, whereas the bill averages longer and thicker. When the length 

 of culmen is divided by the length of tarsus, the quotient gives an index of pro- 

 portion that is very constant, and which quite sharply separates the two species, 

 the index for wardi falling always definitely below that of occidentalis. 



Referring to the specimens examined of the so-called wuerde- 

 manni, he finds that the above characters are intermediate between 

 the two species and show a tendency to approach the characteristics 

 of the species to which the specimen seems to be the most closely 

 related. 



In the light of the above facts, there seems to be little, if any, 

 evidence to support the color phase theory and much to support 



