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taking note of their actions ; second, by destroying individuals 

 at different times and seasons, and examining the contents of 

 their alimentary organs, to ascertain the quality of their food. 

 Mr. Bradley, an English writer, mentions a person who was 

 led by curiosity to watch a pair of birds that had a nest of 

 young, for one hour. They went and returned continually, 

 bringing every time a caterpillar to their nest. He counted 

 the journeys they made, and calculated that one brood could 

 not consume less than five hundred caterpillars in the course of 

 a day. The quantity consumed in thirty, at this rate, by one 

 nest, would amount to 16,000. Suppose that every square 

 league of territory contained one hundred nests of this species 

 — there would be destroyed by the bfrds of one species alone, 

 a million and a half (1,500,000) of caterpillars, in the course 

 of one month for every square league of agricultural territory. 



I was sitting at the window one day in May, when my sister 

 called my attention to a Golden Eobin in a black cherry tree, 

 devouring the common hairy caterpillars ; and we counted the 

 number he consumed while he remained on the branch. The 

 time that elapsed was one minute by the watch, and during 

 this space he destroyed seventeen caterpillars. But it is worthy 

 of notice, that he did not swallow the whole insect. After 

 seizing it in his bill, he carefully set his foot upon it, tore it 

 asunder, and swallowed a small portion taken from the inside. 

 He then seized others in succession, and in like manner selected 

 and devoured his favorite morsel. Had he consumed the 

 whole caterpillar, five or six only would probably have satisfied 

 his appetite. But this is not the general practice of birds that 

 devour hairy caterpillars : they eat only an interior morsel, 

 and require a proportionally greater number to satisfy their 

 wants. 



This observation led me to consider how vast an amount of 

 benefit this single species of birds must contribute to agricul- 

 ture. We will suppose that each bird spends, at different 

 times during the day, sixty minutes, or one hour, in the ag- 

 gregate, feasting upon this kind of food. This is not an ex- 



