WHERE BIRDS MIGRATE 



Migration by Populations Within Species 



Both length and duration of migratory journeys vary greatly 

 between families, species, or populations within a species. Bobwhite, 

 western quails, cardinals, Carolina wrens, and probably some of the 

 titmice and woodpeckers are apparently almost or entirely 

 nonmigratory. These species may live out their entire existence 

 without going more than 10 miles from the nest where they were 

 hatched. 



Many song sparrows, meadowlarks, blue jays, and other species 

 make such short migrations that the movement is difficult to detect 

 because individuals, possibly not the same ones, may be found in one 

 area throughout the year while other individuals that move south 

 may be replaced by individuals from the north. Information on 

 different movements of this type, within a species, can be gained by 

 observing birds marked with numbered bands, colored materials, or 

 identification of racially distinct museum specimens. 



The American robin is a good example of this type of movement. 

 This species occurs in the southern United States throughout the 

 year, but in Canada and Alaska only during the summer. Its 

 movements are readily ascertained from study specimens. The 

 breeding robin of the southeastern states is the southern race. In 

 autumn most of its more northern nesters, such as those from 

 Maryland and Virginia move into the southern part of the breeding 

 range or slightly farther south. At about the same time the northern 

 American robin moves south and winters throughout the breeding 

 and wintering range of its smaller and paler southern relative. Thus 

 there is complete overlap of wintering ranges of northern and 

 southern American robin populations, although some individuals of 

 the northern race winter in areas vacated earlier by the southern 

 race. 



Among many migratory species there is considerable variation 

 among individuals and populations with respect to distances moved. 

 Certain populations may be quite sedentary while others are strongly 

 migratory, and certain individuals of the same population can be 

 more migratory than others. For example, red-winged blackbirds 

 nesting on the Gulf Coast are practically sedentary, but in winter 

 they are joined by other subspecies that nest as far north as the 

 Mackenzie Valley. In certain populations of the song sparrow and 

 other species, males remain all year on their northern breeding 

 grounds while the females and young migrate south. 



Several species containing more than one distinguishable 



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