CLASSIFICATION AND LIFE HISTORY 17 



to their stock. Lastly, it is permissible to ask how is it that 

 when the young birds emigrated to more congenial surround- 

 ings they omitted to take their parents with them ? Each of 

 these points presents a difficulty, and the combination of them 

 renders the migration theory untenable as an explanation for 

 the absence of birds at any time up to the beginning of August. 



Another favourite theory is that all the young birds have 

 been drowned, and if it so happens that there has been a severe 

 thunderstorm in June the theory becomes a certainty though 

 not a single drowned chick may have been found on the moor. 



There is no doubt that many young Grouse are destroyed 

 by drowning, either as a result of being caught in a drain by a 

 heavy shower, or by the flooding of low-lying ground. It is 

 impossible to estimate the loss occasioned by drowning in sheep 

 drains, owing to the extreme difficulty of detecting the small 

 corpses in the swollen stream. One of the Committee's corre- 

 spondents, a gamekeeper, who makes it a rule to inspect all 

 the drains upon his ground several times during the nesting 

 season, states that on one occasion only has he found a drowned 

 chick in a drain. This evidence is, of course, only negative, 

 and against it has to be reckoned the fact that many observers 

 have spoken definitely as to the damage arising from this cause. 

 On many moors the sheep drains have been scoured by floods 

 into deep chasms, from which it would be difficult for the chick 

 to emerge on the approach of danger, and any one who has 

 seen a hill drain immediately after heavy rain, when it is run- 

 ning bank high in a miniature torrent, can picture the risk 

 which might attend any attempt on the part of the mother 

 bird to lead her brood over the obstacle. Much may be done 

 to minimise this risk by forming little backwaters in the drains, 

 with shelving banks by which the young Grouse may escape 

 in time of danger. With regard to flooding, it is necessary to 

 speak with more reserve. Flooding is a gradual process, and 

 the instinct of self-preservation, which teaches the young Grouse 

 to hide from his foes, will doubtless also teach him to retreat 

 before the rising waters. In one case, however, flooding is 



B 



