34^ Ornithological Observations and Reflections in Shetland. 



it is a very gradual — softening of the voices, but why should 

 silence fall thus suddenly, at intervals, and this, too, at a time 

 when, though, by the clock, it may be called evening, no 

 feather of darkness has yet floated ' from the wings of night ? ' 

 In short, there is no apparent reason : some mood of mind, 

 beyond one's human grasp or understanding, has swept, as a 

 breath of wind, through the bird army, acting like a command. 

 Thus, fifteen years ago, I put a fact upon record, which I 

 could not, then, and am still unable to explain orthodoxl}^ 

 though, in doing this, it never, for one moment, occurred to 

 me that I was not acting quite fairly by orthodox science, 

 supposing, as I did and had reason to, that to bring the matter, 

 thus, to public and popular notice, was the surest way of 

 hushing it up. Conceive my surprise v/hen, in a work on 

 ornithology, published only a year afterwards, I found my 

 observations referred to, and others, of a similar kind, brought 

 forward in confirmation. The work in question is Mr. Henry 

 J. Pearson's ' Three Summers amongst the Birds of Russian 

 Lapland,'* and he gives his experience as follows: — 'As we 

 lay ' (the author and his brother) ' watching some bird to 

 its nest, suddenly without the slightest apparent cause, the 

 babel of voices ceased, and every bird in sight. Terns, Gulls, 

 Skuas, even some of the Ducks, would rise into the air in 

 silence, wheel about, several times, and then return with 

 redoubled chatterings. We were the only human beings on 

 the island, at the time ; nor were there any other large mam- 

 mals there, or birds of prey. No signal was perceptible ; it 

 was as if an electric shock touched them simultaneously. 

 Sometimes these peculiar movements took place at intervals of 

 less than ten minutes. 'f In regard to the numbers of the birds 

 affected by this simultaneous impulse — we have seen that 

 they included several species — Mr. Pearson writes : ' Arctic 

 Terns were now nesting in thousands in all directions — on the 

 wet sphagnum-moss in the marshes, on the crowberry covering 

 the higher ground, and among the shingle of the shore, so 

 that when it is remembered that the island meaures four 

 miles each way, and that no part was really free from breeding 

 birds, although they were certainly much thicker in some 

 places than others, it will be clear that " thousands " is not 

 an exaggeration. 'J Here the sudden silence, though it must 

 have been very striking, was, perhaps, no more than an ordinary 

 incidence of the rising in flight, or, at any rate, have had some- 

 thing to do with this. But the one thing is as hard to explain 

 as the other, and the conditions prevailing — the numbers and 



* K. H. Porter, 1904. 



t p. 33- 



X p. 32. I should hardly think it would be an exaggeration as applied 

 to the Terns which I watched. 



Naturalist, 



