318 BULLETIN OF TIIE 



Many of the earlier ornithological writers regarded, as is well known, a 

 considerable proportion of the rapacious birds of North America as iden- 

 tical with species inhabiting the Old World. More accurate comparisons 

 of specimens from the two continents, however, eventually revealed ap- 

 preciable differences between them, and one after another of those of the 

 American continent were regarded as specifically distinct from their Old 

 World relatives; and now there is not one of the diurnal species that has 

 not been separated by one author or another. The owls of the two conti- 

 nents, with two exceptions, have also been similarly separated. While in 

 many of these cases there are appreciable differences that seem more or 

 less constant, in the majority of instances there appears to be no just causo 

 tor the separation. Especially is this the case in respect to Falco peregri- 

 nus (as already observed), Falco candicans, Archibuteo lagopus, Aquila 

 chrysaelos, Pandion halia'elus, Olus vulgaris, Brachyotus palustris, Nyctale 

 Tengmalmi, and Strix jiammca, in all of which species the American birds 

 have been specifically separated from the. European. Buteo borealis, 

 Astur alricapillus, and Falco columbarius present stages of plumage that 

 are scarcely distinguishable from certain stages of respectively Falco 

 cesalon, Buteo vulgaris, and A slur palumbarius , and it is hence not strange 

 that each of these European species have been described by many 

 good authorities as occurring in the northern parts of North America. 

 Certain styles of plumage presented by Falco columbarius, especially 

 at northwestern localities, so strongly resemble common phases of F. 

 cesalon, that one is readily puzzled to know whether to recognize the 

 latter as also inhabiting North America, or whether, since these types 

 imperceptibly grade into the so-called typical F. columbarius, all should 

 not be regarded as forming a single species, since they differ essentially 

 only in coloration, and never very widely. The specimens of F. asalon 

 before me (all immature) mainly differ from average specimens of F. colum- 

 barius of corresponding age in being less ferrugineous, the style of color- 

 ing being the same in both. 



83* Falco sparverius Linn€. Sparrow Hawk. 

 Falco sparverius Lixx£, Syst. Nat., 128, 17GC; and of subsequent Writers gen- 

 erally. 

 Fuku dominicrnsis Gmelin, Syst. Nat., I, 285, 1788. 

 Falco gracilis Suainsox, Lardncr's Cab. Cyc, 281, 1838. 

 Falco cinnamominus Swainsox, Ibid., 281. 

 Falco Isabel I inus SwAlNSON, Ibid., 281. 

 Falco sparveroides Vigors, Zool. Journ., Ill, 4.'!G, 1827. 



Abundant. Breeds in March. As has been previously pointed out, 

 though not observed by all writers, the sexes differ greatly in color, the 



