139* BIEDS OF ILLINOIS. 



Length, about 24.0U-28.00; expanse, 37.00-45.00; weight about V& lbs. (Audubon); wing, 9.80- 

 12.00; tail. 3.10-4.40; culmen, 2.50-3.20; depth of bill. .50-.65; tarsus, 3.10-3.85; middle toe, 2.90-3.00; 

 bare portion of tibia, 1.00-1.35. 1 



Subgenus Ardetta Gray. 



Ardeola Bonap. Synopsis, 1828 (teste Gkat, Gen. & Subg. 1855. 113). Type, Ardea exilis 



Gmel. (Not of Boie, 1822!) 

 Ardetta Gray, List of Genera, App. 18(2, 13. Type, Ardea minuta Linn. 

 Erodiscus Gloger, Handb. i, 1842, 410. Same type. 

 "Ardeiralla" (1855) Vebeeaux (teste Habtl. Orn. Westafr. p. 224). Type, Ardea sturml 



Wagl. 

 Subgen Char. Extremely small (the smallest of) herons, or miniature bitterns; dif- 

 fering from the true bitterns chiefly in their diminutive size, and in the fact that the sexes 

 differ in color. 2 



Although only two species of Ardetta are known to occur in 

 North America (with one additional species in South America), 

 there are various species in other parts of the world. 



The two North American species differ as follows: 



o 1 . Primaries tipped with cinnamon-rufous or pale cinnamon; adults with a distinct nar- 

 row stripe of buff along each side of back B. exilis. 



a". Primaries without rufous or cinnamon tips; adults without trace of lighter stripe 



along sides of back B. neoxenus. ;i 



This species, which was originally discovered in southern Florida, has also been taken 



in Ontario, Canada, and may possibly occur in Illinois. It is very different in color from 



B. exilis, the prevailing colors being black and rich chestnut. 



Botaurus exilis (Gmel.) 



LEAST BITTERN. 



Popular synonyms. American Least Bittern; Tortoise-shell Bird, or Tortoise-shell Bittern 

 (Jamaica) ; Little Yellow Bittern; Ardeola and Pescadora (Mexico). 



Little Bittern Penn. Arct, Zool. ii, 1785, 453, No. 359 (part). 



Minute Bittern Lath. Synop. iii. 1785, 66 (Jamaica); = female ad.). 



Ardea exilis Gmel. S. N. i, pt. ii, 1788, 645, No. 83 (based on the Minute Bittern of Lath. 



t # c .).— Wils. Am. Orn. viii. 1814, 37, pi. 65, fig. 4.— Nutt. Man. ii, 1834, 66.— Aud. 



Orn. Biog. iii, 1835, 77; v, 1839, 606. pi. 210; Synop. 1839, 263; Birds Am. vi, 1843, 100, pi. 



366. 

 Ardetta exilis Gundl. J. f. O. 1856, 345. -Baied. B. N. Am. 1858, 673; Cat. N. Am. B. 



1859, No. 491.— Ridgw. Nom. N. Am. B. 1881, No. 498.— Coues, Check List 2d ed. 



1882, No. 667. 

 Botaurus exilis Reichen. J. f. 0. 1877, 244.— A. O. U. Cheek List, 1886. No. 134.— Ridgw. 



Man. 1887, 127. 

 ? Ardea spadicea Gmel. t. c. 641 (Reichenow). 



1 From measurements of twenty-five adult specimens. 



2 We can find no other difference in form or proportion between Botaurus and Ardetta. 

 In the sexed specimens of A . involucris which we have been able to examine there is no 

 sexual difference of plumage. The sex of the single supposed female, however, may have 

 been incorrectly determined. 



» Ardetta neoxena Cory, Auk, iii, Apr. 1886, 262.— Botaurus neoxenus Ridgw. Man. N. 

 Am. B. 1887, 127. 



