30 



it is given. This may vary also with the character of the food. 

 Fruits, berries and greens pass through in about one-half the 

 time required for boiled rice, crackers, eggs, and the like. Yet. 

 even these are never retained long enough to be more than half 

 digested. 



Observations of this kind were easily gotten by giving each 

 time only the following varieties of food: Crackers, soaked in 

 raw egg or milk; raspberries, boiled rice, crushed blue or huckle 

 berries, and hard boiled eggs. Occasionally these were varied 

 and others added for the day. It was found that rice was liable 

 to cause constipation, and so it was sometimes mixed with 

 crushed sweet apple, lettuce, or grass cut up fine. Seeds and 

 groimd grain, as Indian meal, were little, if any, digested. Like 

 all other birds, these require a certain amount of mineral mat- 

 ter which is supplied in the natural state by the cuticle of in- 

 sects, or dirt that is in them or gotten with them. To make up 

 this deficiency in artificial raising, and to keep the digestive 

 tract in a healthy condition, it was found that plain dirt or fine 

 sand answered the purpose as well as anything. Accordingly, a 

 small quantity of it was mixed with their food two or three 

 times a day. If. however, this was not sufficient, ground shells 

 were added. The young of birds do not require any water. The 

 moisture in most foods, combined with the saliva from the par- 

 ent's mouth is sufficient until they are old enough to fly and eat 

 of their own accord. 



The food of a bird is, to a certain extent, an acquired charac- 

 teristic, and birds can be taught to eat things that are entirely 

 unnatural to them. As. for example, a young robin that had 

 been raised on soft food was placed, as soon as it was old enough 

 to feed itself, in company with an adult chipping sparrow caught 

 when full grown. Soft food for the robin and seeds for the spar- 

 row were kept in seperate dishes inside the cage. The robin being 

 young naturally imitated the sparrow and took to eating seeds. 

 Later it seemed to prefer these to the softer foods and finally 

 it was fed entirely on them. 



Some interesting data was gotten in regard to the rate of 

 growth as compared with the amount of food taken. It was not 

 convenient to weigh each individually and compare it with the 

 amount of food given it; so the plan was followed of weighing 

 the total quantity of food eaten at each meal and comparing the 

 total daily quantity consumed with the gain in weight from day 

 to day. The following is the total amount eaten daily as com- 



