MIGRATION OF PACIFIC PLOVEE HENSHAW. 557 



of food. No such conditions appear to confront the winter sojourn- 

 ers of Hawaii. During its stay in the islands the plover, as also the 

 turnstone, feeds chiefly in the upland pastures and clearings, up to 

 6,000 or 7,000 feet, and on newly-plowed cane land. Both the sugar 

 planter and the stock raiser have much to thank the plover for, since, 

 while the birds feed on small seeds to some extent, they live chiefly 

 on insects, and according to Perkins, on insects of much economic 

 importance, since they depend largely on the caterpillars of two of 

 the most widely spread and destructive of the island " cut worms." 

 These insects are most abundant when the grass on the island pastures 

 is green and luxuriant, and this usually is in winter when rains are 

 most copious. That the supply of food in winter and spring is ample 

 is sufficiently attested by the fact that the birds get into such excellent 

 condition. Even if it be assumed that the supply of food in summer 

 is less than in spring, and hence inadequate for the needs of the 

 thousands that winter here, together with their young, still there is 

 enough to sustain very many more than the comparatively small 

 number of nonbreeders that summer here. 



From the standpoint of the food supply it is even more difficult 

 to explain why the tattler and the curlew leave the islands in spring, 

 since these birds feed almost wholly alongshore, where there can be 

 no appreciable difference in the quantity of food summer and winter. 



The question why the island plover migrate is all the more diffi- 

 cult to answer when we remember that the islands have been perma- 

 nently colonized by certain other American birds, such as the 

 Hawaiian stilt among the Limicolse, the night heron of the Hero- 

 diones, the Hawaiian mud hen and gallinule of the Paludicolse, the 

 Hawaiian goose, the short-eared owl, and the island buteo. These 

 birds came to the islands as waifs, as did the plover. Finding room, 

 shelter, and food abundant, they wisely elected to roam no more, but 

 to become permanent residents, and to forswear for all time the 

 perilous and unnecessary habit of migration. Since they successfully 

 resisted the impulse to return to their former summer homes to nest, 

 then why not the other species? As stated above, the failure of the 

 plover and turnstone to become permanent colonists is not because 

 they SLve crowded out by other ,species. In fall the migrants from 

 Alaska find the inviting island pastures unoccupied, and as they find 

 them in fall, so they leave them in spring. 



I can suggest no very convincing answer to the question, but I 

 in?ij note the significant fact that the present suitability of the islands 

 as a breeding ground for the plover and turnstones is very recent as 

 compared with the birds' acquaintance with them. The cleared strip 

 around each island now planted chiefly to cane, which may be roughlj' 

 stated to be 3 miles wide, and the extensive clearings above this 

 strip which serve for pasture for cattle, are less than 100 years old, 



