on their way north, so that when they arrive at the northern nesting 

 grounds they are paired and ready to proceed at once with raising 

 their families. Mallards and black ducks may be observed in pairs as 

 early as December, the female leading and the male following when 

 they take flight. Naturally, these mated pairs migrate north in 

 company, and it was largely to protect such pairings that duck 

 shooting in spring was abolished by Federal law. 



In the coastal subspecies of the western flycatcher, the sexes 

 appear to migrate in synchrony during the spring in contrast to 

 migration of Hammond's flycatcher in which the adult males usually 

 precede the females (Johnson 1973). Both sexes of the common 

 blackcap of Europe appear to migrate together at least across the 

 eastern end of the Mediterranean during the spring (Fig. 9). 



Blackcap 



Numbers captured 

 300 



250 



200 



150 



Correlation 0.99 



100 



Figure 9. Numbers of male and female blackcaps captured daily in mist nets during 

 spring migration at Eilat, Israel, in 1968. At this point in their migration the sexes 

 are passing through the area at the same time. In other species (e.g., the buntings in 

 Fig. 8), the males often preceed the females. 



39 



