ARDEID^ — ARDEIiX.E: HERONS. 873 



often in large communities, building a large flat rude structure of sticks. The eggs vary in 

 number, coincidently, to some extent, with size of the species ; large Herons generally lay 

 2-S-4, smaller kinds 5-(J ; the eggs are somewhat elliptical in shape, and usually of an uuva- 

 riegated bluish or greenish shade. The voice is a rough croak. The sexes are nearly always 

 alike in color (remarkable exception in Ardetta); but species in which, as in the Bittern, the 

 plumage is nearly unchangeable, are very few. Probably no birds show greater changes of 

 plumage, with age and season, than nearly all Herons. Their beautiful plumes are only worn 

 <luring the breeding season ; the young invariably lack them. There are still more remarkable 

 ditt'erences of plumage in many cases, constituting didiromntism, or permanent normal difier- 

 ence in color, like that of " red" and " gray " specimens of Megascops. Thus, some species are 

 pure white at all ages and seasons, in botli sexes, other individuals of the same species being 

 variously colored. Such dichromatism appears in our Ardea occidentcdis, Dichromanassa rufa, 

 and Florida ccerulea. It was formerly believed, in the cases of the two latter, that the white 

 were the young, the colored the adults ; but it now appears that the difference is permanent, 

 and independent of age, sex, or sea.son. Many species are pure white at all times, and to these 

 the name of Egret more particularly belongs ; but I should correct a prevalent impression that 

 an Egret is anything particularly different from other Herons. The name, a corruption of the 

 French word "aigrette," simply refers to the plumes that ornament most Herons, white or 

 otherwise, and has no classificatory meaning ; its application, in any given instance, is purely 

 conventional. The colors of the bill, lores, and feet are extremely variable, not only with age 

 or season, but as individual ]>eculiarities ; sometimes the two legs of the same specimen are not 

 colored exactly alike. The 9 is commonly smaller than the $ . Normal individual variability 

 in stature and relative length of parts is very great ; and it has even been noted that a specimen 

 may have one leg larger than the other, and the toes of one foot longer tlian those of the other 

 — a circumstance perhaps resulting from the couimon habit of tliese birds of standing fnr a long 

 time on one leg. 



North American ArdeidfC, if not the whole family, are divisible into 2 subfamilies — 

 Ardeiiue or Herons projjcr, and Botaurince or Bitterns. 



Analysis of Suh/amilies, Genera, and Subgenera. 



BoTAURiN*. Tail-feathers 10. Two pairs of powder-down tracts. {Bitterns.) 



Very small ; length about a foot. Sexes unlike Ardetta 



Medium sized ; length 2 feet or more. Sexes alike Botaurus 



ARDEIN.E. Tail-feathers VI. Tliree pairs of powder-down tracts. (Herons.) 



Bill stout and comparatively short, not longer tlian very short tarsus, which is not perfectly scutellate in front. 

 (Sight Herons.) 



Gonys convex, like culmen ; tarsus longer than middle toe and claw Nyetanassa 



Gonys about straight ; tarsus about equal to middle toe and claw Aycticorax 



Bill ordinary. Tarsus scutellate in front. (Day Herons.) 



Length under 20 inches. Tarsus about equal to middle toe and claw. Greeu Butorides 



Length over 20 inches, under 30. Blue, white, or variegated. 



Blue or white. Adult witliout decomposed feathers on back Florida 



Always wliite. Adult with decomposed recurved feathers on back Garzetta 



Ashy-blue, white below. Bill longer than tarsus Hydranassa 



Length 30, not 3G inches. Blue or white. Tarsus twice as long as middle toe. Bill shorter than tarsus 



IJicfiromaitassa 



Length .30 or more. Entirely white ; no crest ; long decomposed feathers on back Herodias 



Length 42 or more ; of dark varied colors, or wliite ; crested, without dorsal plumes Ardea 



Subfamily ARDEIN/E: True Herons. 



Tail-f.'athers 12 (in all North American genera), broad and .Mithsli. Powder-d'.wn tracts 

 ;? pairs. Tibiae naked b(low. Outer too not shorter than inner. Claws moder.ite. curved. 

 (Embracing most species of the family, and all ours except liilterns.) 



