134 Wild Birds and their Haunts 



Everard Home, that Montagu's objections are valid, for 

 in the Adjutant (Ciconia argala), which has a bag precisely 

 similar, he found that it contained ' ' nothing but air, 

 which the bird has the power of expelling and filling the 

 bag again at pleasure." In the adjutant the bag com- 

 municates with the large air-cells at the back of the neck, 

 and therefore we may fairly conclude it is intended to 

 render the birds light and buoyant for running, since they 

 are too heavy to fly without considerable difficulty. 



These birds are remarkable for the length of their legs, 

 which must be very advantageous for swiftness of 

 running ; but it would be wrong to infer as a general 

 principle that all birds with long legs are swift-footed. 

 On the contrary, the Wading Birds (Grallatores) , which 

 have proportionately much longer legs than the ostrich or 

 the bustard, are not well adapted for walking on land. 

 Amongst these the Flamingo (Phcenicopterus ruber) is 

 one of the longest legged birds ; yet it is in this respect 

 far exceeded by the Stilt (Himantopus melanopterus) , and 

 the legs in the latter are, besides, slender, and even ' ' so 

 flexible," as Wilson says of the American stilt, ' ' that they 

 may be bent considerably without danger of breaking," 

 as if, in accordance with Pliny's name (Himantopus), they 

 had been cut out of a thong of leather. 



The reasoning of naturalists, indeed, respecting the con- 

 formation of the feet of birds is, when not derived from 

 living specimens, as frequently wrong as right. It has 

 been usual, for example, since the time, if I mistake not, 

 of Gesner and Aldrovand, to consider the peculiar struc- 

 ture of the foot in parrots and woodpeckers, with two toes 

 before and two behind, as so peculiarly characteristic of 

 climbing birds that in systematic classifications the birds 

 which have their toes so placed are denominated climbing 

 birds (Scansores) ; but, unfortunately for this division, 

 many species which have the feet so constructed have 

 never been observed to climb, such as the cuckoo and the 

 wryneck, while many species which do climb, such as the 

 Nuthatch (Sitta) and the Creeper (Certhia) have their toes 

 placed in the usual manner. 



White's remarks on the walk of birds are well worth 



