LIFE HISTORIES OF NORTH AMERICAN GUIXS AND TERNS. 297 



insects seek shelter on the lee sides of the reeds, which means a 

 bountiful harvest for the terns. 



Behavior. — The black tern is a restless waif of the air, flitting 

 about hither and thither with a wayward, desultory fliffht, light and 

 buoyant as a butterfly. Its darting zigzag flight as it mounts into the 

 air to chase a fluttering moth is suggestion of a flycatcher or a night- 

 hawk; as it skims swiftly over the surface of the water it reminds 

 me of a swalloAv ; and its true relationship to the terns is shown as 

 it hovers along over the billowy tops of a great sea of tall waving 

 grass, dipping down occasionally to snatch an insect from the 

 slender, swaying tops. When looking for food the bill is usually 

 pointed downward, but in ordinary flight it points forward. Mr, 

 Thompson (1890) made some calculations as to the speed at which 

 this tern flies and arrived at the following conclusions : 



A large number of observations resulted in an average of three wins; beats 

 per second, witti the greatest of regularity ; another series of observations, not 

 so satisfactory, allowed a distance of 5 yards to be traversed at each beat. 

 This gave only the disappointing rate of something over 30 miles per hour, 

 but this was at the uncertain foraging flight. Once the mother tern has se- 

 cured her load of provender a great change takes place, as already mentioned. 

 She rises high in air, and I am sure she doubles her former rate of speed, and 

 straight as a ray of light makes for home. It is said that many birds can not 

 fly with the wind ; not so the tern ; for now, if there be a gale blowing her way, 

 she mounts it like a steed and adds its swiftness to her own, till she seems to 

 glance across the sky, and vanislies in the distance with a speed that would 

 leave far behind even the eagle, so long the symbol of all that was dashing and 

 swift. 



The ordinary call note of the black tern, given in flight when not 

 particularly disturbed, is a short, sharp, shrill, metallic '•'•krihP 

 When much excited this is prolonged into a shrill scream like 

 " kreek " or " craik^'' given with ear-piercing vehemence when at- 

 tacking an intruder near its nest. Mr. Henninger, according to 

 Doctor Chapman (1904), contributed the following interpretation 

 of the notes : 



Call note, "Weed"; note of anger and anxiety, '' Icarr krr"; ordinary uotG 

 heard while on the wing, " gik." 



Doctor Chapman described the note used to call the young as a 

 soft " wheent-wheent-wheentP 



With all the varied inhabitants of the sloughs, its bird neigh- 

 bors, the black tern seems to live in peace and harmony. I have 

 never known it to molest the eggs or young of other species, or to at- 

 tack the adults, nor can I find in print any evidence of its hostility. 

 It is not as sociable as some other species, and its nests are usually 

 somewhat apart from others. As a species it is sociable and grega- 

 rious to a limited extent, and it shares with other terns the habit of 

 gathering in flocks to hover over a fallen companion. 



