THE NIGHTJAR :u,7 



drew attention remains to this day a mystery. It is not the body of 

 the claw itself that is serrated, but its inner edge, 

 which, as shown in the MM "r*f > yfiig drawing, is 

 extended to form a thin, flexible, but strong 

 comb with about ten notches, the number van'- 



- 1.1 i . 



ing from bird to bird, and from one foot to the TO. * r*o* 

 other foot in the same bird. It hat been thought 

 that the use of the comb was to clean the gape bristles. Macgillivray 

 denied this, on the ground that the bristles were too big to be inserted 

 in the notches. 1 But an examination of the skins at the Natural 

 History Museum, South Kensington, shows that some of the notches 

 in each comb are wider than others, and are quite wide enough to 

 admit a bristle almost up to its base. The real difficulty lies not in 

 the width of the notches, but in the absence of satisfactory evidence 

 that the bristles need so elaborate an instrument to keep them in 

 order. The flycatchers (Musicapidw), and, indeed, some of the night- 

 jars, 3 are without the comb, though they have the bristles. A third 

 sn^fstion IN that the pectinated claw a-sist^ the nightjar in maintain- 

 ing its favourite perching position, which is along a bough. As, how- 

 ever, the pectinated fringe is on the inner side of the claw, is flexible 

 and yielding, it is difficult to understand how it can be of much use in 

 preventing side slips of the foot For this purpose the points of the 

 claws would prove more effective. Moreover, the nightjar is in the 

 habit of crouching on the bough, so that the need for special supports 

 is not apparent. And certain species, like the coursers and stone- 

 curlew, which have the serrated claw, do not perch. A convincing 

 explanation has, therefore, yet to be found, and for this we must wait 

 till a much closer study of the habits of the species has been made. 



It is less difficult to find an explanation of the nightjar's habit of 

 perching on a bough lengthwise, a position in which it is frequently 



> History of Birds. I'll 033444. 



* Xyctibiusjatnacieiitis has distinct bristles, but neither as stiff nor an large for the size of 

 the bird as oar nightjar. Podarytu ttrigoidft has not, strictly speaking, bristles, bat bristly 

 feathers (shafts with a few barbs.) Neither have the to* pectinated. 



