ON THE USEFULNESS OF BIRDS. 343 



from GO. At this rate five young birds would eat about 300 insects each day, or about 

 9,000 a month for each month, exclusive of the parents. There have been widely dif- 

 ferent estimates as to the number of insects that old birds eat, but it ought not to be 

 difficult to approximate the quantity. Only a small part of the contents of a bird's 

 stomach is entire enough to be distinguished and counted. If the balance is composed 

 as largely of insects, which is more than probable, then the whole number eaten dur- 

 ing a day by an insectivorous bird must be near 200. I reached the same conclusion 

 by actual tests. In the fall of 1874 I bought two Bartramian plovers from some boys 

 who had trapped them, and kept them for a week in a cage before they were set free, 

 I fed them locusts and other insects, which I counted for four days with the following 

 result : 



1st day 277 



2d day 452 



3d day 448 



4th day 439 



Total 1,616 



Average per day 404 



Average for each I 202 



I was compelled to go away or else the experiment would have been continued 

 longer. About one-fourth of the insects were locusts, and the balance were flies, ants, 

 beetles, &c. I gave them whatever insects the boys that I had hired gathered for me. 

 Oa the lirst day I failed to get all that they would have eaten, but afterward they 

 had all that they wanted. My impression, however, is that they ate less than they 

 would have done if they had been at liberty. But, lest there might be some mistake, 

 and to avoid all possibility of error on the wrong side, we will base our calculations 

 on an estimate of 150 insects each day for a mature plover. At this rate 20 old plov- 

 ers would eat 3,000 insects each day, or 90,000 a month. And suppose, further, that 

 thesa 20 plovers had ten nests, which averaged foar young ones each. At 60 insects 

 each day for each young plover, the 40 would consume 2,400 every 24 hours, or 72,000 

 a month. The 20 plovers and their progeny, together, would consume 162,000 insects 

 each month. At this same rate 1,000 plovers and their young would cousume in one 

 month 8,100,000 insects. That many locusts removed in one year from a farm of 160 

 acres would probably render it capable of producing crops even when these insects 

 are doing their worst. As there are many birds that eat more insects than do the plov- 

 ers, as well as many that eat less, 150 insects a day is probably a fair average for all 

 insectivorous birds. 



Here we meet with still other topics of misapprehension on the part of the general 

 public. It is as to the abundance of insects and their prolific character. Many can- 

 not understand how there can be enough insects to feed birds that devour them at this 

 rate. But it is well known among all naturalists that the lower forms of life are mar- 

 velous for the number of species and of individuals and for their fecundity. 



When I first came to Nebraska, in December, 1864, there were many species of birds 

 far more abundant than they have been during recent years. I never saw the black- 

 birds so abundant as they were during 1865 over Eastern Nebraska. As I stated under 

 the head of Bremer's Blackbird, vast numbers of them were poisoned around the corn- 

 fields in spring and fall during these years, so that often piles of them could be seen at 

 once that had been gathered together. It was done under the mistaken notion that 

 the blackbirds were damaging the crops, especially the corn. Great numbers of birds 

 of other species were destroyed at the same time. A single grain of corn soaked in 

 strychnine would suffice to kill a bird. For several years previous to my coming this 

 practice had been going on. In a single autumn, in Dakota County alone, not less than 

 30,000 birds must have been destroyed in this way. Supposing that each of these birds 



