Yellowlegs and other shore birds return to Delta 

 from their breeding grounds in early summer. 



southward migration takes place, there is 

 a heavy mixture of birds-of-the-year with 

 the adults. This mixture, however, may 

 not be taken as a rule for all kinds. In the 

 Golden Plover most adults are said to go 

 south along the Atlantic seaboard, where- 

 as the young, and some adults, travel 

 south in a broad movement across the 

 prairie regions of the continent ( Rowan, 

 1926). 

 There are many other kinds of birds, such as Catbird, Baltimore Oriole 

 and Yellow Warbler, which remain solitary near the breeding territory, 

 quietly inconspicuous during the molt, but announcing their presence in late 

 August with autumnal song. 



The primary wandering of juveniles 



The urge to roam must be innate in young birds, and the random nature 

 of their travel indicates no awareness of geographic direction (Figure 20). 

 Thorpe (1944:77) suggests that such juvenile explorations lead to "latent 

 learning," and he remarks that this is "especially characteristic of animals 

 which explore their environment without the satisfaction of any immediate 

 reward, but by their explorations secure information which may afterwards 

 be of use to them in a number of contexts, for example, in food-getting, in 

 escape from enemies, or in finding their way home." Such wandering serves 

 to give the young bird a familiarity with a wide area beyond the birthplace, 

 and this geographical experience must be an important factor in the homing 

 orientation of the following spring. 



Williams (1944), speaking especially of juvenile Redheads, says that 

 "the available evidence indicates a vagabond existence for the birds until 

 they concentrate on the wintering grounds." The extent of the youthful 



144 



