150 Hairy Caterpillars 



shoots, and in order to obtain sufficient nitrogenous material from 

 this rather low-grade food — low, I mean, in the percentage of nitrogen 

 — it is necessary to ingest it in very large quantity, and to deal with 

 it very rapidly after ingestion. 



There is, therefore, a large crop in which food can be rapidly 

 gathered and stored ; a very powerful, muscular gizzard, in which 

 the heather is thoroughlv ground between a number of hard quartzite 

 pebbles, before being passed on into the duodenum ; and, finally, 

 you notice the exceedingly long paired cseca, for retaining and 

 absorbing the intestinal contents, and effectively extracting the 

 nutritive properties before evacuating the useless residue. 



A Grouse, like a grass-fed cow or sheep, has to spend the best 

 part of the day in gathering food and digesting it, and that because 

 of its low nutritive value. Similarly, an Irish peasant living on 

 potatoes has to eat a vast quantity, in order to obtain sufficient 

 nitrogen (proteid), and, incidentally, gets more starchy food (carbo- 

 hydrates) than he requires, and no fat at all. Half-a-pound of beef- 

 steak would be worth a whole kettle-full of potatoes. 



For the purposes of my argument, I have taken heather as the 

 only food of the Grouse, and that is true in a general sense, but, of 

 course, they often secure food of a much higher dietetic value at 

 certain seasons of the year, e.g., grain, ripe fruit, insects of various 

 kinds and their larva;. 



There is one article of diet which is present on the moors in 

 quantity' from summer to late autumn — hairy caterpillars of various 

 kinds, more especially the larvae of the Fox moth [Bomhy.x rubi) — 

 but the birds — game birds I mean — won't look at them. 



I have seen the moor literally swarming with hairy caterpillars, 

 and yet I have never found one in a single example of tlie rather 

 numerous Red- and Black-Grouse I have examined. 



The food value of these larvae is high ; the Grouse could have 

 gathered a full meal in a very few minutes, but never a one was 

 touched. 



Smooth larva- I have found on dissection, but these were never 

 sufficiently abundant on the open moor to form any considerable 

 item of their bill of fare. 



To the general rule that birds leave hairy caterpillars severely 

 alone, there is one marked exception — the Cuckoo — there may be 

 other exceptions, but I do not know of them. 



It is probable that, under sufficient stress, other species might 

 overcome their distaste for this diet, and in the absence of anything 

 else, eat the hairy larvas. 



I remember a boy bringing me a live Land-rail which he had 

 picked up on a common in Suffolk ; the bird had struck some 

 prickly wire in its migratory flight, and was sorely crippled. One 

 leg was broken, and also the wing at the wrist (carpal) joint. It 

 couldn't fly, and could only move very slowly and distressfully with 

 the aid of the sound wing and leg. The accident must have taken 



