342 



ODICNEMUS. 



pressed toward the tip. The culmen of the upper 

 mandible is elevated, and that of the lower forms an 

 angle a structure of bill which combines the two 

 properties of lightness and strength. The nostrils 

 open longitudinally in the middle of the length of the 

 bill, and are in part protected by a horny plate. The 

 legs are long and slender, with three toes to the front, 

 but not even a rudiment of a hind toe. The three 

 front toes are bordered with a membrane which unites 

 them as far as the first joint ; and this structure of 

 foot possesses great elasticity, and also affords a firm 

 plant or base to the bird in running. The enlarge- 

 ment of the knee, or rather of the ankle, from which 

 the birds get their common name, is produced by the 

 enlargement of the upper end of the tarsus, and the 

 bones with which that is articulated. By this means 

 a sort of cross lever power is given to the joint, which 

 enables the bird to have great command over the 

 tarsus, while the dry soil upon which it chiefly runs 

 does not require.very great weight or general strength 

 in that bone. The wings are of mean length, but 

 they are rather pointed, the second feather being the 

 longest. The tail is wedge-shaped, and the general 

 form of all the organs of flight adapts the birds well 

 for turning on the wing, or otherwise having a power- 

 ful command of the air. 



Though this genus of birds were long confounded 

 with the plovers, there is a remarkable distinction 

 between them. Plovers, though they prefer open 

 places and not woods, do not betake themselves ab- 

 solutely to the desert ; whereas the thick knees are 

 always found on dry sands, and generally remote 

 from the dwellings and the labours of man. They 

 are exceedingly timid, and generally remain concealed 

 during the day, so that one may pass near the places 

 where they are without having the slightest chance 

 of seeing them. When, however, the twilight closes 

 in, the birds take advantage of its shade to come 

 abroad on their feeding excursions. Their food con- 

 sists of small ground animals, such as slugs, insects, 

 and the more minute reptiles ; all of which are, like 

 themselves, abroad chiefly in the twilight. During 

 the night they fly with rapidity, and utter a sharp 

 plaintive cry, which is heard at a considerable dis- 

 tance. During the day the sound which they utter, 

 when alarmed or otherwise excited, is in a deeper 

 key, and heard at a much less distance. At these 

 times they trust more to their legs than to their wings 

 in seeking safety from enemies. There are very few 

 animals of the same localities which can overtake 

 them in running ; the chief danger to which they are 

 exposed is from birds of prey in the air, and by keep- 

 ing the ground they can escape these better than if 

 they were to take the wing. Birds of prey, which 

 kill on the ground, could not descend with certainty 

 upon a thick-knee if once alarmed, because that bird 

 would be far enough out of the way before the enemy 

 reached it ; and as even those birds which prey on 

 the ground, upon other birds or warm-blooded ani- 

 mals, must make a rush in the air in order to acquire 

 the requisite impetus, it becomes impossible for them 

 to make any thing of a bird which can run swiftly. 

 Owing to these circumstances, the day flight of the 

 thick-knees is always low and taken in short reaches. 

 Their chief security upon the ground, however, con- 

 sists in their being so like the colour of the sand, and 

 squatting so closely upon it, tkzi birds of prey cannot 

 see them. 



Their's is a wide range in nature, but it is exceed- 



ingly laborious ; and therefore, besides their noctur- 

 nal activity in ranging from place to place, they are 

 obliged to migrate with the seasons. They proceed 

 northward about the month of April, and are driven 

 south again by the autumnal rains. On their migra- 

 tions they generally keep in flocks, resting during 

 the day, and making their passage during the night 

 with rapid wing, and apparently encouraging each 

 other by their cries. When the nesting time comes 

 the flocks break up, as is common with all birds which 

 breed in comparatively bare pastures. Indeed this 

 is so general a habit that it is necessary to be attended 

 to by every one who wishes rightly to understand 

 the nature of birds, and their general uses in the eco- 

 nomy of creation. If the birds nestle where food is 

 abundant for them, they are generally social in their 

 nesting places. We have this exemplified in rooks, 

 in herons, in house sparrows, and many others, espe- 

 cially of those birds of the rich tropical forests which 

 load the trees with their nests. Of these social 

 breeding birds it appears that the one excites the 

 other, and the encouragement thus mutually given 

 makes the labour proceed with greater celerity. But 

 there is of course a limiting of this encouragement 

 which bird can give to bird in the performance of 

 labour ; for, though the stimulus of a neighbour's 

 voice and activity may prompt to labour, it cannot 

 find a reward for that labour, unless such a reward is 

 obtainable in the locality. We have often a very 

 striking illustration of this in the case of the common 

 rook. If, during the incubation, and especially after 

 the young are beginning to break the shell, a severe 

 frost should set in, and close the earth and the brooks 

 for a succession of days, there is grievous lamenta- 

 tion among the dark inhabitants of the trees. The 

 females cannot of course leave their charge, and thus 

 the males are on the wing far and near in quest of a 

 supply. This, which is always obtained with great 

 labour under such circumstances, is often exceedingly 

 scanty ; and the complainings are sometimes painful 

 to an experienced ear, as they express sufferings 

 which are severely felt and cannot be relieved. 

 When a kindly thaw comes, and the stores of the 

 earth are again opened, the cawing of the rooks be- 

 comes exceedingly joyous ; and no one would easily 

 believe, if he had not carefully observed the fact, that 

 notes so different in their sound and expression could 

 be uttered by the same birds, at perhaps an interval 

 of not more than two or three days. 



Those birds which disperse at the pairing time are 

 not subject to these casualties, because each has 

 a sort of farm to itself, upon which no bird of the 

 same species intrudes. There are not perhaps any 

 two distinct species of birds which feed upon exactly 

 the same sort of food ; and therefore the dispersed 

 birds are not so liable to suffer from other species as 

 they would be from their own. 



Birds which thus disperse in the breeding time 

 rarely have any battles of gallantry among the males. 

 Each pair betalces itself to its own station, where the 

 two remain during the season in constant attendance 

 upon each other. The female chooses some little 

 hole sheltered by a tuft or bush, in which she depo- 

 sits her eggs, which are usually two in number, gene- 

 rally of a greenish-yellow ground and spotted with 

 brown. The young are carefully nursed for a time 

 by the parent birds ; and they are at least two or 

 three years in acquiring the plumage of full maturity, 

 which is gradually arrived at by a single yearly mpult. 



