640 DOMESTIC ANIMALS, DAIRYING, ETC. 



it is true, the effects of a combined attack of birds upon caterpillars, 

 cankerworms, or other insects which are present in unusual numbers 

 or have played havoc with the foliage, are too evident wholly to es- 

 cape attention; but more often birds work unnoticed, and the good 

 they do is not at once obvious to the busy farmer. There are few 

 visible tokens of the process by which the crop of hay or green feed 

 has been saved from the cutworms by crows, or the potato crop res- 

 cued from the Colorado beetle by the grosbeaks. The birds have 

 done their work quietly but none the less effectively. They have 

 saved, or greatly assisted in saving, the farmer's crop, and nobody is 

 the wiser, save the few who make it the business of their lives to study 

 the habits of birds. 



The time has long passed when the practical fanner can afford 

 to ignore the relation of birds to agriculture. Larger and larger areas 

 are being devoted to tillage every year, and the amount of capital in- 

 vested in agricultural pursuits in the United States is constantly in- 

 creasing. Irrigation, until recently almost unpracticed in the United 

 States, is fast assuming national importance. The whole world is 

 being laid under contribution for new fruits, forage plants, and 

 crops for the benefit of the American farmer, in order that by his 

 superior energy and foresight he may not only feed our own people 

 but create a surplus of American products for consumption in less 

 favored lands. 



Along with these new introductions and as a necessary result of 

 international commerce, new pests have been introduced. Here, un- 

 der a favorable climate and new conditions, they multiply till they 

 inflict great damage. The Hessian fly, 'San Jose scale, and codling 

 moth are examples in point. 



Such pests usually go unnoticed until the damage they do forces 

 them on the attention of a community, when usually they are so 

 numerous and widespread that their extermination is impossible. 

 Once introduced into the country they are here to stay, and the vast 

 sums already spent in efforts to stay the ravages of such pests em- 

 phasize the importance of utilizing to the utmost all the allies nature 

 places at our disposal. 



As a means of checking these introduced insect pests, as well as 

 native ones, birds are of vast importance. Yet it must be remem- 

 bered that, when once the productive powers of insects have had full 

 play and an invasion occurs, the farmer can not suddenly augment 

 the number of birds and summon the winged hosts to his aid. Birds 

 reproduce but slowly, and in the natural course of events often suffer 

 immense losses during their migrations, by climatic extremes and 

 through the assaults of birds of prey and predaceous mammals. 

 Hence a marked increase in the number of birds, either as a class 

 or in the case of a given species, must come slowly and as a result of 

 favoring conditions extending over a term of years. Moreover, as 

 stated above, birds alone are inadequate to cope with sudden insect 

 irruptions. It is their province rather by incessant watchfulness and 

 constant warfare to prevent over-production of insect life rather than 

 to reduce excess, although in the latter regard their aid is important. 



