THE BIRDS AND MAMMALS 01 IMAW BUM. 755 



This suggests two possible explanations. 



(i) That there had been an epidemic amongst the young birds themselves in 

 1913 or 1914. 



{it) That there was an epidemic amongst insects in one or other of those 

 years, with consequent lack of food for the young birds. 



Considering the great irregularity of the chmate in a mountainous region such 

 as the N. E. frontier subject to a highly modified monsoon, the whimsicality 

 with which a month will be fine one year and pouring with rain the next, such 

 epidemics may be more common than is usually supposed. 



If the Lisus are one enemy of bird life on the N. E. frontier, snakes are another. 

 During the summer months small snakes of all kinds literally swarm in the 

 temperate forest belt between 6,000 and 9,000 feet ; and the curious thing is 

 there are far more snakes there— or at least they are far more commonly met 

 with — than in the hot semitropical valleys. During the rains of 1919 I rarely 

 went into the forest without meeting at least one snake, generallj' two or 

 three. Most of them were no doubt harmless to man — they were at any rate 

 quite small reptiles ; but it was otherwise with birds. 



And now comes the strangest thing of all. 



The great majority of small birds met with seemed to build their nests on, or 

 close to the ground. 



The fact that without any search, I ran into (it is the best expression) thirteen 

 nests with eggs or young between June 1st and July 3lst, says something for 

 the bird life of the country. Of these, one was probably, and two were possibly 

 beyond the reach of snakes ; the rest were all either actually on the ground, or 

 in long thick grass within a foot or two of it. I had long suspected, from seeing 

 broken egg shells on the ground and finding nests deserted, that snakes took 

 heavy toll of the birds, and at last I obtained direct proof. 



One evening I flushed a small bird off a nest in the long grass which bordered 

 the pathwaj^ below the village, at an altitude of 5,000 feet. There were three 

 sky blue eggs, like an English hedge sparrow's, which the nest also resembled. 

 These I left, deciding to return next day and spot the bird. 



As I approached the place next morning I saw the male bird hopping about 

 in the bushes close to the nest and twittering, evidently in great distress. At 

 first I supposed I was the cause of alarm, but on approaching closer and peering 

 into the nest I saw a small black snake with narrow yellow rings, calmly coiled 

 up in the bottom of the nest sucking the eggs ; it escaped my efforts to kill it 

 and left the nest gutted. 



The snake was not above 18 inches long, the nest about the same height above 

 the ground. 



However there were plenty of small birds seen above 8 000 feet, and at this 

 altitude snakes were more rare. In 1914 I saw two vipers in a marsh at about 

 8,000 feet altitude, and in 1919 a snake three feet long came into our camp, in a 

 marshy meadow at 9,000 feet, and was promptly killed. No doubt in such 

 localities plenty of snakes might be met with. 



It may be observed in passing that an abnormal number of snakes in one year 

 might imply a decrease in the number of birds during the following year ; and 

 conversely, a decrease in the number of birds might re -act unfavourably on the 

 number of snakes in the third year, allowing the number of birds to become nor- 

 mal again in the fourth — if indeed the ravages of one season can be made 

 good again so rapidly. 



I wish, however, in particular to insist on the number of snakes in the 

 Htawgaw Hills ; and in general to point out that in a country so proUfic of life, 

 there is a destruction of life correspondingly prolific. 



In August the common Yunnan green parrot was often seen in the valley. 

 On some days numbers of swallows (?) would be seen wheeUng and darting over 

 the village. Then they would disappear mysteriously and not be seen again fov 



