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first week in April — that the males begin to show a slight 

 interest in the presence of the females. The former now spend 

 more of their time in the marsh, and resent intrusion into 

 their domains. By this time their reproductive organs show 

 considerable increase in size (Plate XXI, E). Among the 

 migrating birds at this time there is an increasing preponder- 

 ance of immature males and of females. The latter shun the 

 presence of the males, and whenever they do approach one 

 of the residents, they are immediately driven off. A flock of 

 fifteen females has been observed to be dispersed by a single 

 male and actually prevented from alighting in the marsh 

 undisturbed. This flock, after circling about the marsh and 

 attempting to alight several times, was finally forced to leave. 

 Arrival of resident adult females. — During the early part of 

 the third week in April, another group of females arrives. The 

 flocks break up and the single birds scatter over the marsh, as 

 did the resident males upon their first arrival. Usually they 

 select a place near some male or group of males. They are 

 much more retiring than the latter, however, and keep mostly 

 near the water's surface, where they are inconspicuous. 

 Whenever they appear on the tops of the cat-tails, or more 

 especially, when they attempt to fly, they are immediately 

 pursued by one or more of the males. Occasionally a male 

 drives a female in great circles over the marsh and even to a 

 considerable height. Eventually, however, he relinquishes the 

 pursuit and returns to his post. The earlier migrant females, 

 when pursued in this way, immediately leave the marsh. 

 But now, as the male ceases pursuit, the female checks her 

 flight and is soon again at her station near the male. Such 

 maneuvers announce the arrival of the resident females. The 

 resident males now remain the entire day in the marsh. The 

 females at first leave the marsh during the middle of the day, 

 but return to the same spot each night. Occasionally a 

 female is found to have selected a spot near a male, and for 

 some reason remains unmolested or even scarcely noticed by 

 him. Ordinarily she is persistently persecuted, and can not 

 appear above the cat-tails without being pursued. She always 

 returns, nevertheless, to the same area. After a varying 



