170 BULLETIN 113, UNITED STATES NATIONAL MUSEUM. 



near the end. There is a slight roseate suffusion on the breast in 

 this i)lumage. Perhaps the flight feathers are not molted again 

 that year, but undoubtedly the plumage of the head is replaced by 

 the winter plmnage like that of the adult, and perhaps the wings 

 may also be molted again during the late summer or fall. I have 

 been unable to trace into subsequent plumages the peculiar wing 

 acquired during the first spring, nor do I know when it is replaced. 



The next step toward maturity we find in birds in both nuptial 

 and winter plumages in which the plumage is fully adult except the 

 primaries. This is undoubtedly the second year plumage, and the 

 inference is that it is acquired at a complete postnuptial molt 

 when the bird is a little over a year old, which means that the two 

 complete molts are only about six months apart. In this plumage 

 the primaries are black for a distance of about 3 inches from the tip 

 on the outer and for a decreasing distance on each succeeding pri- 

 mary. The tips of all the primaries are white, sometimes for an inch 

 or so on the outer, and sometimes there is an indistinct white spot 

 in the black of the outer primary. At each succeeding molt the 

 black in the primaries decreases and the white increases until only 

 a small black area remains on each primary. There is apparently 

 much individual variation in the extent and rapidity of this change. 



The complete postnuptial molt of adults occurs mainly in Au- 

 gust and September, but it is often not completed until October. 

 The outer primaries are the last to be renewed. Winter adults have 

 the forehead, lores, and throat white, and the occiput, cervix, loral, 

 and auricular regions densely mottled or washed with slate gray. 

 The beautiful nuptial plumage is acquired by a partial or perhaps a 

 complete prenuptial molt in April and May. 



Food. — The food and feeding habits of the Franklin's gull demon- 

 strate its value to the agricultural interests of the west, and prove 

 that it is almost wholly, if not entirely, beneficial to mankind. Dur- 

 ing the nesting season, at least, its food is almost whollj' insectiv- 

 orous. 



Doctor Roberts (1900) says of its food at this season: 



The stomachs and gullets of several birds collected by the writer and kindly 

 examined by Professor Beal, of the Biological Survey at Washington, con- 

 tained a mass of insect debris to the exclusion of all else. One stomach alone 

 furnislied some 15 different species, among them several varieties injurious to 

 the interests of man. The chief part of the food, however, during the time of 

 our visit to the colony, and that on which the young wei'e largely fed, was 

 the nymphs of dragon flies, which were then to be found in immense numbers in 

 the meadows near by. The writer counted no less than 327 of these insects in a 

 single stomach. 



Early in the spring, when the farmers are plowing, these gulls 

 follow the plow in large numbers, contending with the blackbirds 



