26 BIRDS OF CALIFORNIA AFFECTING FRUIT INDUSTRY. 



of insects, many of them harmful, the tanager has a fair claim to con- 

 sideration at the hands of the farmer and even of the orchardist. 



It is probable that means may be found to prevent, at least in part, 

 the occasional ravages of the tanager on the cherry crop. The tan- 

 ager, like the robin, prefers to swallow fruit whole, and as the latter 

 takes small wild cherries in preference to the larger, cultivated kinds 

 when both are equally accessible, it is probable that the tanager Avould 

 do the same; and it is suggested that a number of wild cherry trees 

 planted around California orchards might prove an economical in- 

 vestment for the orchardist. 



SWALLOWS. 



Swallows are the light cavalry of the avian army — always on the 

 move, always on the skirmish line, ever gathering stragglers from 

 the insect camps. They furnish another instance, and perhaps the 

 most remarkable one, of change of habit induced by civilization. In 

 eastern United States the bank swallow and the rough-wing are the 

 only species that adhere persistently to their original nesting sites. 

 In the West a third species may be added to these, the violet-green 

 swallow ; but there all the swallows are somewhat less domestic than 

 in the East. It is probable, also, that some species, notably the barn 

 swallow, are more abundant than when the country was unsettled, 

 owing to the increased number of nesting sites. Supposing for a 

 moment that the country was swept bare of buildings, where could all 

 the barn swallows find suitable places to nest? The cliff swallows 

 might discover enough overhanging cliffs upon which to attach their 

 mud domiciles; the white-bellied and the martin, as formerly, might 

 nest in the hollows of trees, but there are not caves enough east of 

 the Mississippi River to afford nesting places for one-tenth of the 

 barn swallows. In the far West they would fare better. When the 

 country was first settled, barn swallows must have been confined to a 

 few rocky cliffs and caA r es here and there along the seashore or in 

 mountains. Now they live wherever man has erected a structure of 

 any kind. 



As is to be inferred from the movements of these birds, their food, 

 with some curious exceptions, consists principally of insects caught 

 in mid-air. For this reason all the species are migratory, except in 

 the Tropics, for the food supply fails in regions where frosts prevail. 

 As many insects that usually do not fly, periodically ' swarm,' they 

 are often captured by swallows at such times in great numbers. Such 

 is the case with ants and 'white ants' (Termitidae), which most of 

 the time are concealed in the earth or in logs, but at certain times 

 1 swarm ' in immense numbers. Many species of beetles that live in 

 offal and ordinarily are not accessible to birds, in case of failure of 



