ORNITHOLOGY. 



567 



Insessores. chiefly on insects — in the West Indies (if the species are 

 s ""~y^— 'identical), on rats and reptiles. 



Order II.— INSESSORES or PERCHING BIRDS. 1 



This is the most numerous order of the class of birds, 

 and, as Cuvier has observed, is distinguished chiefly by ne- 

 gative characters ; for it embraces all those various groups 

 which, sometimes possessing but little in common, are yet 

 in themselves neither raptorial, scansorial, grallatorial, na- 

 tatorial, nor gallinaceous. At the same time they exhibit 

 a eeneral resemblance to each other in structure, and pre- 

 sent such gradual transitions from group to group, as to 

 render definite subdivisions by no means easy. 



They are said to possess not the violence of birds of 

 prey, — meaning thereby our preceding accipitorial order. 

 Yet a fly-catcher crushing the body of a slender-limbed and 

 delicate gnat, a blackbird pertinaciously dragging a reluc- 

 tant worm from its subterranean dwelling, or a sparrow 

 with his bill as full of tortuous caterpillars as it can con- 

 tain (to say nothing of the butcher-bird, which is said to 

 impale his prey alive upon " the blooming spray"), is as- 

 suredly as raptorial or predaceous as need be well desired. 

 Neither can the division of the smaller birds into granivo- 

 rous and insectivorous be strictly maintained, though we 

 doubt not that the strong, conical billed species eat most 

 greedily of seeds and grain, while those of softer and more 

 slender bill are chiefly avidous of insect life ; — but all pre- 

 cise divisions, founded on the love of any special diet, must 

 be received with reservation, — seeing that almost all passe- 

 rine birds feed both themselves and young in spring and 

 early summer with what may be correctly called animal 

 food (that is, insects and worms), while in autumn and 

 throughout the winter season they just as generally (and 

 for the best of reasons) have recourse to all manner of 

 seeds and grain. The tender-billed birds are certainly 

 more dependent on insect food than the others, and it is 

 consequently among them that we find the greater propor- 

 tion of our migratory species ; for as the increasing dull- 

 ness of autumn depopulates the busy world of insect life, 

 so our finest songsters (the familiar red-breast forming a 

 delightful exception) take then their departure for other 

 climes, not so much by reason of the immediate influence 

 of cold upon themselves, as because they find their accus- 

 tomed food becoming daily less abundant. Such of the 

 insectivorous tribes as remain with us throughout the year 

 assuredly combine the graminivorous diet with their more 

 favourite food, just as the hard-billed species sustain them- 

 selves during spring and summer by the capture of insects. 

 In tropical countries, where the seasons are less strongly 

 or differently marked, and the death-like torpidity of our 

 northern winters is unknown, this periodical change of food 

 may probably either not obtain, or be less perceptible in 

 its occurrence ; but as we know that over a great part of 

 the globe it is true, that for one portion of the year most 

 insect-eating birds feed on seeds, and that for another por- 

 tion of the year most seed-eating birds feed on insects, we 

 may be permitted to doubt the propriety of rigorously di- 

 viding the great body of passerine species into insectivo- 

 rous and granivorous sections. We admit that, either 

 from the nature of things, or the feebleness of human lan- 

 guage, the terms applied to the greater divisions of natural 

 history ought not to be construed according to their strict- 

 est literal interpretation, as they are frequently of a con- 

 ventional character, and have in some cases been substi- 

 tuted for numerical signs, as more easily held in remem- 

 brance ; but it is nevertheless to be greatly desired, that 



those who are influential in the nomenclature of science Insessores. 

 should avoid bestowing appellations which convey an erro- '— "■v^'-' 

 neous idea of the objects intended to be expressed. 



The feet of the insessorial order are especially formed 

 for perching, the hind toe springing from the same plane 

 as the anterior ones, — a structure which gives them great 

 power in grasping. Their legs or tarsi are always of mo- 

 derate length, and the claws not strongly curved. The 

 form of the bill is too various to be generalized ; and the 

 same may be said of the length of the wings, of which the 

 comparative breadth generally bears relation to the habit 

 of life of each particular tribe. The stomach is in the 

 form of a muscular gizzard, generally preceded by a greater 

 or less expansion in the shape of crop, and there are usu- 

 ally two very small ca;ca. The lower larynx is very com- 

 plicated, especially among the various tribes of songsters. 

 We must now rest satisfied with these brief and barren 

 generalities. " The great order of Passeres or Insessores of 

 authors," Mr Macgillivray observes, " is so heterogeneous 

 in its composition, that all who have attempted to charac- 

 terize it, whether in few or in many words, have utterly fail- 

 ed ; for this plain reason, that its various groups are as un- 

 like to each other as they are to the Raptores or Rasores, 

 and that in fact the only common features which they ex- 

 hibit are those of the general organization of birds. A 

 hornbill and a humming-bird, a parrot and a wren, a king- 

 fisher and a swallow, a starling and a toucan, not to men- 

 tion others still more dissimilar, are surely as unlike each 

 other as a hawk and a shrike, a pigeon and a plover, or a 

 flamingo and a pelican." 2 



The first principal division of the passerine birds con- 

 sists of those genera in which the external toe is united 

 to the internal by not more than one or two of the joints, 

 and contains the four great tribes of Dentirostres, Fissiros- 

 tres, Conirostres, and Tenuirostres. 



Tribe 1st. — Dentirostres. 



Bill with a marginal notch towards the extremity of the 

 upper mandible. 



The dentirostral tribe is composed chiefly of insectivo- 

 rous groups, and, according to the modern views, contains 

 the following five families, viz. Laniadm, Merulidce, Syl- 

 viada, Ampelidce, and Muscicapidte. We do not think the 

 general reader, with whose tastes the treatises in our En- 

 cyclopaedia are for the most part made to conform, would 

 be benefited by our entering into the complexities of these 

 circular arrangements, or by an extended exposition of the 

 innumerable minor groups of which the families are com- 

 posed. We shall therefore here content ourselves by no- 

 ticing the principal generic groups which form as it were 

 the groundwork on which the more elaborate systems have 

 been erected, and with which it is necessary to become 

 familiar in their more general and comprehensive form, 

 before their minuter subdivisions (to be elsewhere studied) 

 can be understood. The genera are chiefly determined 

 by the form of the bill, which is strong and compressed 

 among the shrikes and thrushes, depressed in the fly- 

 catchers, rounded and thickish in the tanagers, slender and 

 pointed in the warblers, — but in each and all exhibiting 

 different degrees of the typical character, or a tendency to 

 transition, which admits of various systematic views. 



Mr Swainson divides the Laniadae or shrikes into five 

 sub-families, viz. Laniance, or true shrikes ; Thamnophili- 

 nm, or bush-shrikes ; Dicrurince, or drongo shrikes ; Ceble- 

 pyrinee, or caterpillar catchers ; and Tyrannina, or tyrant 

 shrikes ; and each of these contains a great variety of ge- 



Pice and Passeres, Linn. 



BritUh Birds, vol. i. p. 311. 



