128 TKANS ACTIONS OF THE IlililNOIS 



are so different as to enable any novice to distinguish between them at a 

 glance. In fact, a friend mentions, as I write, two birds whose nests are 

 much more easily distinguished than the birds themselves. 



Satisfactory as this argument seems, I do not wish to rest too much 

 upon it, and I will content myself with concluding that there is a fair 

 probability that the stomachs of these forty-one birds give us a correct 

 general idea of the ordinary food of the robin under such conditions as 

 have prevailed in this State during the last three years. When a species, 

 or its nest, or its eggs, may be very well described from two or three 

 specimens, I may reasonably express some confidence in conclusions 

 based upon these forty-one stomachs. 



I must, however, make one correction. In one important particular 

 my conclusions may be unfair to the bird. I have taken no account of 

 the food of the young ; and the robin is said by many observers to feed 

 its young largely on worms, larvae and soft-bodied insects. Doubtless a 

 good many earth-worms are taken in this way, but grubs, cut-worms and 

 caterpillars are also said to be used.* 



The experiments of Prof Treadwell, of Cambridge, as to the voracity 

 of young robins have been so often cited that I will only recall the fact 

 that he was compelled to feed his young robins every day at least their 

 own weight of insect-food, or its equivalent in flesh, to keep them from 

 starving to death. 



This species is not strictly migratory, but sometimes winters, in 

 considerable numbers, as far north as the White Mountains in New 

 Hampshire. I have not heard of its occurrence in winter in Central or 

 Northern Illinois, as there is at that season no sufficient food to tempt it 

 to brave our prairie winds. On the other hand, it is comparatively rare 

 in Southern Illinois in summer, but abundant there in autumn and winter, 

 so that as far as this State is concerned it is practically a migrant within 

 our limits. In the latitude of Bloomington its advent depends on the 

 forwardness of the season, but it usually appears not far from the first of 

 March, and the last of the species are gone by October 15th or Novem- 

 ber ist. 



During the month of March the food of the two specimens I exam- 

 ined consisted almost wholly of grasshoppers and some diptera larvae, 

 pronounced by Prof. C. V. Riley to be those of a long-legged fly, Bibis 

 albipennis (Say.), which feeds upon decaying vegetation. Sixty-seven per 

 cent, of the food consisted of these larvae, and twenty-four per cent, of 

 the grasshoppers. This same larva was found by Prof. Jenks, now of 

 Brown University, to constitute about nine-tenths of the food of the 

 robins examined by him in Massachusetts in February and March, 1858, 

 a fact which indicates a remarkable fixity of food-habits unchanged by 



* The parents of the young mocking birds mentioned in the foot-note to p. 121, 

 being allowed to feed their young for a time after the transfer of the nest to a cage, 

 were observed to bring them at first grasshoppers and caterpillars, and a little later 

 pieces of ripe tomato also. The pulp of water-melons, exposed as an experiment, they 

 look with avidity and fed it to the young. It is possible that the amount of " soft 

 food" fed to the young has been exaggerated. 



