RARE PLANTS IN BRITAIN 
69 
to twist one wing in the wind, for it makes a sound like that pro- 
duced by cutting the air sharply with a cane, only much louder. 
These parasites torment the birds much, and sometimes seem 
to overcome them altogether. I was once opening some new 
holes under the south eaves for the swifts to build in, when I 
found a swift clinging to the end of a rafter. It did not move 
when the top of the ladder was placed near it, and it allowed 
itself to be taken by hand. With a pair of scissors I relieved it 
of eight of these horrible creatures. They are very nimble and 
can run backwards and forwards and sideways ; and this gives 
them a very uncanny appearance. They have such a hold with 
their claws that they will drag out a small feather sooner than 
let go, even when cut in two. They are not much smaller than 
those which infest the grouse, but their wings are not so fully 
developed— -in fact, they seem quite rudimentary. The swifts 
have also the small flat brown lice on them, but they are not 
troubled by fleas like the house and sand-martins. 
There are one or two undoubted instances of a swift being 
caught by a hobby. I suspect that the victims were caught 
before they knew their danger, either being taken by surprise and 
struck before they had time to get way on, or through treating the 
hobby with the same indifference with which most swifts usually 
regard a kestrel or a sparrow hawk. I can hardly credit that any 
bird could beat a swift that was in good condition in fair flight. 
The female birds will stay out in the longest evenings in 
July catching flies for their young ones as late as 9.15, when one 
would have thought that they could not see their prey. I 
have once seen one out at 9.25. 
The swifts sometimes scream in their nests late at night. 
I imagine that the swifts pair for life like the swallows and 
all the other birds of which both the sexes return to the same 
nest year after year. 
(To be continued.) 
NOTES ON THE DISTRIBUTION OF RARE PLANTS 
IN BRITAIN. 
(Continued from page 43.) 
NUUJg SHALL not dwell long on the second natural Botanic 
I M Garden — the classic Glens of Clova. In them I have 
gathered in abundance Polypodium alpcstre, so out- 
wardly similar to Athyrium Filix-famina, and Poly- 
stichum Lonchitis in as wild profusion as on Ben Lawers. This 
fern, I may observe, is scarcely a rare, but rather widely distri- 
buted, Scottish fern. I have met with it also in abundance on 
Stronechrubie rocks in West Sutherland, and sparingly on the 
Storr Rocks and the Quiraing in Skye. In South Britain I 
have seen it but once, viz., on Clogwyn y Garnedd, one of the 
