PROTECTION OF BIRDS 



467 



of grain eaten, thus leaving only that portion which can be 

 considered to the bird's discredit. The figures represent the 

 per cent of the total food for the year that any item forms. 



LABORATORY EXERCISE 36 



Purpose. To study the food habits of some common birds. 



Directions. From a study of the above food chart answer 

 the following questions. Copy the following table in your 

 notebook and write in it the answers to questions 1-6 by 

 writing the names of the birds in the proper column and the 

 per cents in order, the largest first. 



1 . Which birds are specially valuable as destroyers of insect 

 pests (50% or over) ? 



2. Which are especially valuable as destroyers of weed 

 seeds (50% or over) ? 



3. Which are valuable for destroying both insect pests and 

 weed seeds (20% or more of each) ? 



4. Which birds feed to any extent on grain (10% or 

 more) ? 



5. Which birds feed to any noticeable extent on cultivated 

 fruit (10% or over) ? 



6. Which birds feed to any extent on beneficial insects 

 (10% or over)? 



7. Which of those birds that feed on grain or cultivated 

 fruit destroy enough insect pests or weed seeds to balance the 

 harm done ? 



