i;8 MY NATURE NOTEBOOK. 



that summer's menace of an early and severe winter 

 has not approached fulfilment yet. But it is early to 

 boast of good luck. A change of wind may at any 

 moment cover the country-side with frost, and our 

 friends with overcoats and mittens. Meanwhile, 

 belated summer birds have here and there been 

 keeping company with the lingering summer flowers. 

 Sand-martins, the smallest of the swallow tribes, 

 have been seen well into November hawking for 

 flies as actively as in June. Although, presumably, 

 the weakest of the swallows, the sand-martin makes 

 these belated appearances so often in mild autumns 

 that Gilbert White strongly inclined to the belief 

 that it laid itself away for the winter in holes and 

 crevices of the cliffs and banks, where it was seen hawk- 

 ing to and fro, to and fro, through all the short hours 

 of early November sunshine; but no exploring of 

 rock-crevice, or digging of sandbank in the winter 

 ever brought a single dormant sand-martin to light. 



THE WORK OF THE WINDS. 



The fact, of course, is that warm south-west 

 winds stop the southerly migration of birds as surely 

 as the north wind compels it ; and it is less correct 

 to quote the lingering presence of summer birds as 

 evidence of the " abnormal mildness of the season " 

 than to regard both the mildness of the season and 

 the presence of the birds as effects of the same cause, 

 the prevalence of southerly winds. For the summer 

 birds have no other guide in their autumn migration 

 than those winds whose chill breath tells of waning 

 insect life. Then they fly ; and the winds which 



