^°'lflO^'"] Henshaw, Migration of the Pacific Plover. 249 



the bird colonists from America, like the owl, night heron, gallinule 

 and coot, have resided in the islands so short a time that they have 

 changed very little from their American ancestry. Others, like 

 the hawk, stilt, and goose, have changed more, and hence pre- 

 sumably have been residents of Hawaii a longer time. Changes 

 of color, proportion, and size, however, be they great or small, 

 cannot be used as time measures, except in the vaguest way, since 

 practically next to nothing is known of the length of time they 

 require. We are perhaps justified in concluding that none of the 

 above species have changed sufficiently to call for isolation from 

 their American ancestors for periods to be reckoned by geologic 

 intervals rather than by thousands of years. 



Spring migration of Plover. — The impulse to migrate in spring 

 is by no means simultaneous among all the plover that winter in 

 the islands, or that winter on any one island; nor apparently is it 

 the rule for large bodies of plover to migrate together. The plover 

 and turnstones, probably often in mixed companies, begin to leave 

 for the north early in April, and the migration continues till at least 

 the latter part of May (probably even later), being dependent 

 apparently on the state of preparedness, or the inclination of 

 individual birds. 



When the time to migrate comes, small parties, from a dozen or 

 even less, to flocks of 200 or more, strike boldly out to the north- 

 ward, apparently without hesitancy or doubt of the result. Mr. 

 Hasvrell of Papaikou, which is on the coast about 15 miles north 

 of Hilo, soon after daybreak during the early days of April, 1900, 

 saw several flocks rise to a great height and, after widely circling 

 about a few times as if to orient themselves, finally disappear in 

 a northerly direction. 



It is probable, however, that day migration is not the rule with 

 plover and other shore birds. Apparently it is more usual for the 

 flocks to feed by day and leave just before nightfall, as do many 

 other birds in different parts of the world. Mr. R. C. L. Perkins 

 states that several times he "witnessed these departures always 

 late in the afternoon, or just before dark." He adds: "When 

 about to return to the north the plover frequently assemble in very 

 large flocks, and before setting out on their journey, rise to an 

 enormous height in the air, even beyond the range of sight. I have 



