BROOD-CARE IN BIRDS 159 



its nature depends partly on the condition of the young chicks. 

 There can be no doubt but that birds are modified reptiles, and 

 most probably ancestral birds, like living reptiles, hatched out in a 

 condition in which they were active and very closely resembled 

 their parents. If they were unable actually to fly, they at least 

 could run about actively, and make fluttering or gliding and para- 

 chute-like motions with their wings. The megapodes are the only 

 living birds that are hatched in such a stage that they are able to 

 fly at once, and in which parental care ceases with the laying of the 

 eggs in a suitable place. It is improbable, however, that these 

 represent an actually primitive condition that has survived. 

 They pass through a moult before they are hatched and it is very 

 likely that their extreme precocity is a comparatively recent 

 acquisition. If we count, not by species, but by orders, sub-orders 

 and really well-separated families, then by far the greatest number 

 of different kinds of birds are hatched in a stage in which, although 

 they are not able to fly, they are alert, active, able to see and to 

 pick up their own food, and all these are clad from the first in a coat 

 of down. Lists of names are not usually interesting, but I am 

 going to give a rough list which, although not complete, will carry 

 conviction. The young of the following groups are active and 

 downy, or precocious when they are hatched : Auks, bustards, 

 cariamas, cassowaries, coursers, cranes, curassows, divers, ducks, 

 geese and swans, emus, flamingoes, frigate-birds, frog-mouths, 

 game-birds (including pheasants and fowls, peacocks, partridges, 

 quail and all their allies), grebes, gulls, hemipodes, hoatzins, jaca- 

 mars, kiwis, nightjars, ostriches, penguins (although these are 

 rather helpless), rails, rheas, sand-grouse, screamers, seedsnipes, 

 sheathbills, shore-birds, (including all the plovers, turnstones, 

 woodcock, snipe, avocets, oyster-catchers, sand-pipers, and their 

 immediate allies), tinamous, turacos and trumpeters. This list 

 plainly includes birds of very different types with very different 

 habits, but I think I can make the general statement about it that 

 it does not include the higher types of birds and notably the perching 

 and singing birds. 



Next, there is a smaller assemblage of birds, to which the penguins 

 in the first list form a halfway stage. In these the young are 

 helpless when they are hatched, but are covered with a coat of 

 down. Such are the American vultures, all the ordinary birds-of- 

 prey, the eagles, hawks, harriers and Old World vultures, herons and 

 bitterns (although in the latter the coat of down is thin and hairy), 



