162 The Ottawa Naturalist. [Mar. 



We are endeavouring to increase the productiveness of the soil ; 

 birds will assist in doing this by destroying those agencies, name- 

 ly, insect pests which decrease the amount produced. 



The quantity of insect food consumed by birds is almost 

 incomprehensible, but the facts set forth by various investigators 

 on this continent and in Europe give us some idea of the extent to 

 which insects go to make up the diets of birds. Insects constitute 

 65 per cent, of the total yearly food of woodpeckers, 96 per cent, 

 of that of fly-catchers, and 95 percent, of the yearly food of wrens. 

 Upwards of 5000 insects have teen found in a single bird's stomach. 

 The value of the birds is increased by the fact that at the time 

 when insects are most abundant birds are most active and require 

 most food, especially animal food, to feed their young. A bird 

 normally requires a large amount of food owing to its active 

 habits and high temperature, all of which bodily functions demand 

 a constant and plentiful supply of fuel in the shape of food. A 

 young crow will eat twice its w T eight in food ; a robin weighing 

 three ounces was found by Nash to consume five and one-half 

 ounces of cutworms in a day. It is calculated that a pair of tits 

 and the young they rear will consume about 1 70 pounds of insect 

 food during a year. These facts and others to be given later will 

 indicate the enormous destruction of insect life that is accompli- 

 shed by the presence of birds. They constitute one of the 

 fortunate balances of nature. But man is constantly upsetting 

 the balance. Woodlands are cut down and give place to 

 open fields; snake fences give way to wire; subdivisions and 

 town lots obliterate the waste places and often the swamps. All 

 these circumstances tend to drive away the birds formerly resi- 

 dent and breeding in such localities. Then outbreaks of injurious 

 insects occur and their depredations are increased and prolonged 

 by reason of the absence of such important enemies. Therefore, 

 our aim should be to restore the balance by attracting the birds 

 back to our parks and natural reservations. 



Not only do birds destroy insect pests, but they contribute 

 to the destruction of weeds. Certain species of our native sparrows 

 are large consumers of such weed seeds as bindweed, lamb's 

 quarters, ragweed, amaranth, pigeon grass, etc. Judd records 

 the result of the examination of over 4000 stomachs of twenty 

 species of sparrows. It was found that for the entire year weed 

 seeds form more than half their food, and during the colder 

 months of the year these seeds constitute about four-fifths of the 

 food of many species. A single bird will often be found to have 

 eaten 300 seeds of pigeon grass or 500 seeds of lamb's quarters or 

 pigweed. Beal estimated that the tree sparrow may consume one- 

 quarter ounce of weed seed per day, and on that basis, in a state 



