656 SYSTEMATIC SYNOPSIS.— EEBOPIONES—HEBOBII. 



There are about seventy-five species, very generally distributed over the globe, but especially 

 abounding in the torrid and temperate zones. Those that penetrate to cold countries in 

 summer are regular migrants; the others are generally stationary. They are maritime, 

 lacustrine and paludicole birds, drawing their chief sustenance from animal substances taken 

 from the water, or from soft ground in its vicinity ; such as fish, reptiles, testaceans, and 

 insects, captured by a quick thrust of the spear-like bUl, given as the bird stands in wait 

 or wades stealthily along. In conformity with this, the gullet is capacious, but without 

 special dilatation, the stomach is small and little muscular, the intestines are long and ex- 

 tremely slender, with a large globular cloaca and a coecum. Herons are altricial, and 

 generally nest in trees or bushes (where their insessorial feet enable them to perch with ease), 

 in swampy or other places near the water, often in large communities, building a large flat 

 rude structure of sticks. The eggs vary in number, coincidently, to some extent, with the 

 size of the species ; the larger herons generally lay two or three, the smaller kinds five or six ; 

 the eggs are somewhat elliptical in shape, and usually of an unvariegated bluish or greenish 

 shade. The voice is a rough croak. The sexes are nearly always alike in color (remark- 

 able exception in Ardetta) ; but the species in which, as in the Bittern, the plumage is nearly 

 unchangeable, are very few. Indeed, probably no birds show greater changes of plumage, 

 with age and season, than nearly all the herons. Their beautiful plumes are only worn 

 during the breeding season ; the young invariably lack them. There are still more remark- 

 able dififerences of plumage in many cases, constituting dichromaUsm, or permanent normal 

 difference in color, like that of the " red" and " gray " specimens of Scops Owl. Thus, some 

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

 species being variously colored. Such dichromatism appears in our Ardea occidentalis, Di- 

 chromanassa 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 season. 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 of the herons, white or otherwise, and has no elassificatory meaning; its 

 apphcation, 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 peculiarities ; some- 

 times the two legs of the same specimen are not colored exactly alike. The 9 is commonly 

 smaller than the $. 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 than those of the other- — a circumstance perhaps result- 

 ing from the common habit of these birds of standing for a long time on one leg. 



The North American Ardeidm, if not the whole family, are divisible into the two subfamilies 

 of Ardemm, or Herons proper, and BotoMrinis, or Bitterns. 



Analysis of Subfamilies, Genera, and Subgenera. 



BoTATJHiNiB. Tail-feathers 10. Two pairs of po-wder-do-wn tracts. (Bitterns.) 



Very small ; lengtli about a foot Sexes unlike . . . . Ardetta 267 



Medium sized; length about 2 feet. Sexes alike Sotaurus 261) 



Abdein^. Tail-feathers 12 Three pairs of powder-down tracts. (Herons.) 



Bill stout and comparatively short, not longer than very short tarsus, which is not perfectly scutel- 

 late in front. (Night Herons.) 

 Gonys convex, like the culmen ; tarsus longer than middle toe and claw .... Nycterodms 265 



Gonys about straight; tarsus about equal to middle toe and claw Nyctiardea 264 



Bill ordinary. Tarsus scutellate in front 



Length under 20 inches. Tarsus about equal to middle toe and claw. Green .... Butmides 263 

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



Blue or white. Adult without decomposed feathers on back Florida 262 



