l6 SMITHSONIAN MISCELLANEOUS COLLECTIONS VOL. 85 



Bird enemies. — The identifications of Annulata from nearctic birds 

 are : 690 for the Polychaeta, chiefly Nereidae, which have been found 

 in the stomachs of more than 70 species of birds and in numbers up 

 to 500 in a single stomach ; 428 for the Oligochaeta or earthworms 

 from 44 species of birds; and 11 of Hirudinea or leeches from 10 

 species. The robin (Plaiiesticus Jiiigratorius) feeds habitually and 

 voraciously upon earthworms and the woodcock (PJiilohela minor) 

 makes about half of its diet of these annelids. 



Number of identifications, 1131; percentage of identifications 

 among those of all animals, .4764 ; percentage of species in this phylum 

 among the whole number of animal species known, .7136. 



Other enemies. — Studies that have been made of the food of fishes 

 indicate that a very large number of marine fishes prey upon the 

 Nereidae and other annelids. They are eaten also by other worms, 

 starfishes, sea-urchins, sea-anemones, gastropods, and crabs. Fresh- 

 water oligochaetes form a steady contribution to the diet of the fishes 

 of their environment. Earthworms are eaten by predacious beetles, 

 by most batrachians, by some turtles, snakes and by various mam- 

 mals including shrews, skunks, and the armadillo, but especially by 

 the moles {Parascalops hrezveri, 26 per cent of the food ; Scalopus 

 aquaticus, 31 per cent; Scapanus fozvnsendi, 40 per cent; Coudylitra 

 cristata, 50 per cent.) Leeches are eaten by a variety of mammals, 

 birds, reptiles, amphibians, fishes, crustaceans, snails, and insects. 



Discussion. — Both of the annelids (Nereis and Aphrodite) Wallace 

 mentions as being warningly colored are eaten by birds and fishes, 

 Nereis frequently and in large numbers. Considering the aquatic 

 habits of most of the annelids it would appear that they are taken 

 by birds as often as could be expected. It is evident furthermore 

 that they have numerous other predatory foes and that they probably 

 contribute their full quota of food toward the dietary requirements 

 of the animal kingdom. 



ARTHROPODA (jOINTED ANIMALs) 



As recorded previously in the table of phyla, the Arthropoda, in- 

 cluding the exceedingly numerous class of insects, furnish, as would 

 be expected, a very large preponderance of the animals eaten by birds. 



Number of identifications, 210,752 ; percentage of identifications 

 among those of all animals, 88.7551 ; percentage of species in this 

 phylum among the whole number of animal species known, 74.6188. 

 The disproportion of the percentage of capture to that of frequency 

 reflects the relatively greater availability to birds of arthropods over 

 the other phyla. 



