LIFE HISTOKIES OF NORTH AMERICAN GULLS AND TERNS. 173 



trait peculiar to almost all gulls. Mr. Preston (1886) says of their 



behavior : 



While defending their nests they evince great courage and spirit, successfully 

 routing the Canada goose (Bernicla canadensis), white pelican (Pelecanus 

 erythrorhynchus) , and other large birds which chanced to molest them. A most 

 distressing sight was the determined but unsuccessful attempt of a dozen 

 frightened gulls to chase a large snapping turtle from a nest on which it had 

 killed the mother bird and was leisurely devouring her eggs. When I ap- 

 proached the nest the owners, with a few others, hovered about crying piteously, 

 almost striking me with their wings. 



Fall. — After the breeding season is over these gulls gather into 

 immense flocks and wander about in search of suitable feeding 

 grounds, where they must prove of great benefit in destroying vast 

 hordes of injurious insects, such as locusts and grasshoppers, which 

 are swarming on the prairies during the latter half of the summer. 

 Mr. George Atkinson, according to Macoun (1909), says of their 

 abundance at that season : 



While driving into the Eagle hills, about 40 miles west of Saskatoon, on July 

 30, 1906, we passed an extensive mud flat and salty slough, on which rested 

 between four and five solid acres of gulls. I fired a shot into the air to note 

 the effect and they rose as one bird in such a cloud that their wings clashed 

 together in a frantic flapping and their discordant cries were almost deafening. 

 It would be entirely impossible to estimate the number of birds in this flock. 



Dr. Thomas S. Eoberts has sent me the following interesting ex- 

 tracts from his field notes on the behavior of Franklin's gulls in the 

 great autumnal gatherings of this species in Minnesota: 



Immense numbers of these gulls spend the nights out in the open lake, congre- 

 gating to form one or two or sometimes three flocks, 600 or 800 feet long and 

 200 or 300 feet wide. The gulls sit close on the water, so that from a distance 

 they look like vast " banks " of ducks, except when the sun strikes them just 

 right, then they show white. During the day the gulls feed on the fields and 

 prairies at some distance from the lake, returning toward evening in various 

 sized flocks and assembling out in the lake for the night. About sunrise in the 

 morning they begin to stir, and for a time there is great commotion among 

 them. Soon they get up in a body and the air is filled with them. As the 

 slanting sun strikes their snowy bodies and slowly moving wings it is a 

 curious and beautiful sight, appearing as though the air were filled with huge 

 snowflakes or eddying bits of silver tinsel. Rising to some distance above the 

 water they start for their feeding grounds in a great straggling company, the 

 head of the flock soon becoming V-shaped as geese fly. Later they break up 

 into numerous smaller flocks, each flying in more or less perfect V-shaped 

 formation. They return at night in the same way or in broad straight-fronted 

 flocks, and when the light makes them appear dark the inexperienced sportsman 

 is apt to think a tempting flock of small geese is approaching. They fly too 

 slowly for ducks. 



On October 4 at 5 p. m. the gulls came from the north at a great height, 

 circling around against the blue sky, appearing like shining white specks as the 

 sun struck their white bodies. The wings were invisible, but their movements 

 caused a flickering or twinkling, causing the gulls to look like stars in the deep 



