26 REPORT OF XEW JERSEY STATE MUSEUM. 



migrants in shaping their course, for it is well known that mountains 

 and river valleys stand out distinctly on moonlit nights, and it is on 

 clear nights only that birds migrate. 



Xight migrants flock together during the flight, forming- an im- 

 mense scattering host of various species, which keep within hearing 

 of one another, if not within sight. 



It is possible to hear the chirping of the passing birds on a quiet 

 night, and they may be seen by the aid of a telescope directed toward 

 the full moon. 



Professor Cooke has recently shown that many birds have as definite 

 winter homes as they have summer ranges, and furthermore, that 

 species which are closely associated during the breeding season may 

 betake themselves to very different regions in winter. For example, 

 the Black-throated Blue Warbler winters in some of the West Indies, 

 passing southeastward through Florida and the Bahamas, while the 

 Black- throated Green Warbler, which has nearly the same breeding 

 range, travels southwestward to Central America for the winter, being 

 practically an unknown species in Florida and the West Indies. 



From the standpoint of any single locality, we may divide our birds 

 into several classes, according to their habits of migration, viz. : 



(1) Residents. Birds that are with us throughout the year. 



(2) Summer Residents. Birds that nest with us, arriving from 

 the South in the spring and returning in the autumn. 



(3) Winter Visitants. Birds which nest to the north of us, but 

 come to our neighborhood to pass the winter, returning in the spring. 



(4) Transients. Birds which nest to the north of us and winter 

 to the south, passing through our territory in the spring and fall. 



(5) Accidental or Irregular Stragglers, which do not normally 

 occur in our district. 



It is obvious that some birds may belong to two classes, as, for 

 instance, such species as breed with us, but winter just a little farther 

 to the south. Some individuals of these may occasionally remain with 

 us for the winter, and thus become Residents, while the bulk of the 

 species are Summer Residents. The Robin is a good example. 



It is also obvious that in a State with such a long extent north and 

 south as New Jersey possesses, some birds may breed in the northern 

 counties, but not in the south, and vice versa. 



The birds of Xew Jersey may be grouped as follows : 



