400 NATURAL HISTORY. 



their usual range, by scarcity of food or other causes ; such are the 

 Nyctea nivea, Astur atricapUliis, Colly rio borealis, Pinicola canadensis, 

 and others. Second, those which visit us in July and August, which 

 are mostly the young of species breeding further south. Examples 

 of these are to be seen in the Rhynchoj^s nigra, some species of Ardei- 

 da?, &c. In the third class are to be ranged those whose appearance 

 is totally accidental, dependent upon no fixed habit of the bird. 

 Thus, species of T hallassidroma and Puffitius have been seen upon the 

 Potomac, and a Milvulus (M.. forjicatus, probably) and the Chamoipelia 

 passerina have been detected. 



The great mass of the birds which pass through the district in their 

 spring migrations do not stop to breed before reaching, at least, the 

 Mew England States, and probably the majority go still further north, 

 spreading through the Canadas and into British America to the region 

 around Hudson's bay. Our regular winter visitants, as the Junco 

 hyemalis, Spizella monticola, and the Anatidce generally, do not usually 

 stop much short of Labrador and the regions of that latitude. Other 

 species, however, breed with equal readiness in almost any latitude. 

 Thus the Dendroica aestiva is very common through the summer in the 

 district, and doubtless even further south; while it breeds also in very 

 high latitudes in British America. During the winter these migra- 

 tory species mostly retire to the Antilles, or into Central America, 

 though many linger in the Gulf States along our southern border. 

 The manner in which these extensive migrations are performed varies, 

 doubtless, with different groups of birds, but it is very difficult to 

 conceive how some weak and short-winged species can perform the 

 immense journey. Some accomplish the distance by continually flying 

 from forest to forest, and from hedge to hedge; while others mount 

 directly high into the air, and uninterruptedly continue their flight 

 until hunger or weariness compels them to desist for awhile. This 

 kind of migration is performed by some species wholly in the night 

 time. Some of the small insectivorous birds have been noticed just 

 at daybreak to descend from a great height, and after remaining 

 motionless for sometime, as if to recuperate their energies, search 

 diligently for food, and again resume their flight towards evening. 

 The distance at which the notes of birds flying overhead can be 

 heard is truly surprising. We have heard distinctly the mellow 

 notes of the Bob-oHinlc while the bird itself was entirely beyond our 

 range of vision. The loud "honking" of wild geese while migrating 

 is well known. 



'A circumstance which has considerable influence on the appearance 

 of birds in the immediate vicinity is the presence of a large city. 

 This is most strikingly shown in the case of the ducks and other wa- 

 ter fowl, to which the attention of the sportsman is especially di- 

 rected. The peculiar character of Chesapeake bay and its tributa- 

 ries render them the favorite winter resort of nearly all the species 

 of Anatidce ; but the incessant persecutions to which these birds are 

 subjected have effected a material diminution of their numbers, and 

 caused a great part of them to retire to the bogs and inlets of more 

 southern shores. The same is true, though less markedly, of various 



