310 ANNUAL REPORT SMITHSONIAN INSTITUTION, 1941 



The examination of stomach contents of wild animals, which has 

 been carried on so extensively by the United States Biological 

 Survey * over a long period, has been of great value in showing what 

 North American animals eat. The studies carried on in this manner 

 are valuable as guides in the keeping of captive animals. 



One of the most common errors in the feeding of carnivorous ani- 

 mals is to give them only choice red meat, on the assumption that 

 carnivores limit themselves strictly to such food. On the contrary, 

 in many cases when carnivorous animals make a kill, they eat the 

 viscera of the prey or drink its blood or eat its brains before they 

 will eat any of the red meat. Kecent studies in vitamins reveal that 

 the viscera of animals are rich in several vitamins ; liver is especially 

 rich, as are other glands of the body. Furthermore, it is probable 

 that the digestive fluids in the stomach and intestines, which are 

 regularly consumed by the carnivores, are really needed by these 

 animals. The fur or feathers and skin of the victims are regularly 

 consumed, and are obviously needed as roughage and bulk if they 

 serve no other purpose. The bones of the victims are relished in 

 many instances and are valuable as a source of minerals such as 

 calcium and phosphorus; also, red bone marrow is a valuable food. 

 Furthermore, the chewing of bones stimulates the flow of digestive 

 fluids and strengthens the teeth and jaws. 



Almost all carnivores will occasionally take plant foods to some 

 extent, as witness the cat that will frequently chew grass, apparently 

 taking it as a medicine or for the vitamins. Dogs do likewise. Bears, 

 other than polars, eat mainly plant products. 



Overfeeding is a frequent cause of animals becoming sluggish or 

 excessively fat, and even dying. Care should be taken to give an 

 animal only as much as it will clean up fairly promptly at its usual 

 time to eat. Surplus food that remains in the cage is likely to spoil 

 and poison the animal, and also to attract ants, flies, cockroaches, 

 and other pests. 



Nocturnal animals will not, of course, ordinarily take food that 

 is given to them in the daytime. Their failure to take it promptly 

 should not be construed as indicating that they are not hungry. 

 They should be fed in the evening. 



Fur farms are probably the most outstanding examples of progress 

 in the care and keeping of wild animals in captivity, for if a fur 

 farm is to profit, it must not only be able to keep its animals alive, but it 

 must be able to induce them to reproduce prolifically and to be in such 

 excellent health that their fur is of superior quality. Furthermore, 



* On July 1, 1940, this organization was consolidated with the U. S. Bureau of Fisheries, 

 formerly of the Department of Commerce, under the new title of U. S. Fish and WUdlife 

 Service, and transferred to the U. S. Department of Interior. 



