270 POULTRY AND WILD BIRDS 
in captivity; another way is to observe the rations brought 
by the parent birds to a nest of young ones; still another 
method is to examine the contents of a bird’s crop; and this 
has been done in hundreds of cases by government experts. 
Each of these methods independently establishes the fact 
that birds as a class consume an enormous quantity of food. 
Nor is this surprising. They are the most active branch of 
the animal kingdom. They are very busy creatures at all 
seasons of the year, — traveling long distances in search of 
food and in migrating. They rear large families, in many 
cases two or three broods in a summer. In short, for their 
size, they do a very large amount of work, and they require 
a corresponding amount of food to supply the energy. 
The Food of Nestlings. — Nestlings will eat one half of their 
own weight of food per day, and even more if they can get it. 
A case is on record of a young Robin that was brought up by 
hand and was fed on cutworms and earthworms, of which he 
was allowed 50 to 75 a day. When three weeks old a test was 
made to see what quantity he really could eat. His own 
weight was then three ounces, and in the course of the day he 
ate just five and one half ounces of cutworms or 165 in num- 
ber. To make room for so much food it is digested in a re- 
markably short time. The wonderful growth and develop- 
ment of young birds is accounted for by the satisfaction of 
their enormous appetite. 
The writer once watched a nest of Wrens for a week and 
counted the number of trips per day that the old birds made 
with food for the young. They began at daylight and worked 
the greater part of the day till dark, bringing 250 insects. 
This gives 50 insects to each of the five young ones. Let us 
feed them at this rate till they go South, which will be in about 
100 days, and 25,000 insects will be required for this brood. 
