viii CASES OF ADAPTATION 133 



early morning to sunset, bringing mouthfuls of food at an 

 average four times in five minutes. This may no doubt be 

 taken as typical of a number of the smaller warblers and 

 allied birds. 



Blue tits, with a larger family, worked continuously for 

 sixteen hours a day at midsummer, bringing about two 

 thousand caterpillars to the ravenous young birds, who, 

 taking the average at ten (and they sometimes have sixteen), 

 would swallow 200 each in the day. A pair of marsh tits 

 were observed to feed their young entirely with small green 

 caterpillars, and in one case made 475 journeys with food 

 in seventeen hours. 



A gold-crest with eight young brought them food six- 

 teen times in an hour for sixteen hours a day. A wren fed 

 its young 278 times in a day. Even the common house- 

 sparrow, itself a typical seed-eater, feeds its young on 

 caterpillars or on small insects which it catches on the wing. 

 A flycatcher was observed to sit on a dead branch of an ash 

 tree near her nest, whence by short flights she caught small 

 flies, etc., on the wing, bringing a mouthful to her young 

 every two to five minutes. 



As every schoolboy knows, the number of nests is very 

 great to those who know how to look for them, some being 

 found in almost every wood, copse, or hedgerow. As examples, 

 in a small copse in Herts, nine different species of birds had 

 nests with young, all within 50 yards of each other. In 

 another case, nests of a tit, a flycatcher, and a wood-wren 

 were found within 10 to 15 yards of each other. In the 

 case of many small birds the whole period, from hatching 

 the eggs to that of the young leaving the nest, is only two 

 weeks, but swifts require from a month to six weeks. 



It must be remembered that the birds carefully clean 

 out the nest after every meal, and in wet or very chilly 

 weather carefully protect their young, and as they must also 

 procure food for themselves, it is evident that their labours 

 at this time are really prodigious. And this vast destruction 

 of insect-life goes on unchecked for several months together 

 and the supply never seems to fail. When the parent 

 birds leave the nest in search of food for their young, they 

 may be seen to fly to some adjacent bush or branch of a 



