RING-OUSELS. 99 



LETTER XXXVII. To T. PENNANT, ESQ. 



DEAR SIR, Selborne, 1771. 



ON the twelfth of July I had a fair opportunity of contemplating 

 the motions of the caprimulgus, or fern-owl, as it was playing 

 round a large oak that swarmed with scarabai solstitiales, or 

 fern-chafers. The powers of its wing were wonderful, exceeding, 

 if possible, the various evolutions and quick turns of the swallow 

 genus. But the circumstance that pleased me most was, that I 

 saw it distinctly, more than once, put out its short leg while on 

 the wing, and by a bend of the head, deliver somewhat into its 

 mouth. If it takes any part of its prey with its foot, as I have 

 now the greatest reason to suppose it does these chafers, I no 

 longer wonder at the use of its middle toe, which is curiously 

 furnished with a serrated claw.* 



Swallows and martins, the bulk of them I mean, have forsaken 

 us sooner this year than usual ; for, on September the twenty- 

 second, they rendezvoused in a neighbour's walnut-tree, where 

 it seemed probable they had taken up their lodging for the night. 

 At the dawn of the day, which was foggy, they arose p]l together 

 in infinite numbers, occasioning such a rushing from the strokes 

 of their wings against the hazy air, as might be heard to a con- 

 siderable distance : since that no flock has appeared, only a few 

 stragglers. 



Some swifts staid late, till the twenty-second of August a 

 rare instance ! for they usually withdraw within the first week.f 



On September the twenty-fourth three or four ring-ousels ap- 

 peared in my fields for the first time this season : how punctual 

 are these visitors in their autumnal and spring migrations ! 



* 1 have noticed this species perform the feat which is here mentioned by Mr. White, but am 

 inclined to attribute to it a rather different purpose, as its foot is manifestly but very ill calculated 

 for capturing prey. It will be observed that, on bringing the foot of a dead motheater towards 

 the mouth, the serrated claw is admirably adapted for detaching the hooked claws of beetles, 

 which must of course often hitch to the sides of the bird's mouth, and impede its swallowing o 

 them. To this explanation it has been objected that some members of this genus are withou 

 this curious appendage, whereas others which have no rictorial bristles are provided with it. 

 would suggest, in the former case, that the food is more exclusively lepidopterous ; and, in th 

 latter, that it evidently is not so much the movable and yielding vibrissae as the corners of th 

 mouth which require the aid of this singular and remarkable structure. The same explanatio 

 will equally apply to the other various birds in which the pectinated claw is observable. Ei>. 



-! \ stray swift has been observed sometimes in September. En. 



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