BIRD. 



435 



lowing their prey to some distance under water, 

 become less capable of motion on land or on the 

 wing, their bills increase in power. We have exam- 

 ples of this in the razor-bill and the puffin, which 

 though they can fly, do not habitually perform that 

 operation ; and still more in the great auk and the 

 penguins, which have very powerful trenchant bills. 

 With these one set of the sea birds may be said to 

 terminate ; and they bear nearly the same relation 

 to the water that the ostrich and apteryx bear to the 

 land it is their principal, and almost their exclusive 

 element. 



Guillimot. 



In the rapid sketch which we have taken of them, 

 we have traced the birds in their regular gradation, 

 from those that feed on foot upon the land, to those 

 that feed by swimming and diving in the water. But 

 the birds bring us out to sea on another element 

 the air ; and there are tribes which take up the con- 

 nexion from the heron and the kingfisher, which fish 

 in the fresh waters only, and the succession continues 

 till we come to races which are as discursive over 

 the sea as the swallows and swifts are over the land. 



But as all these nestle on the shores (for there is 

 no bird that breeds in the water), and as none of 

 them can be insect feeders on the wing over the sea, 

 there being no insects there, there is not the same 

 diversity of habit among them as there is among the 

 air-feeding birds of the land. The living produce of 

 the shoreward parts of the sea, the waste and refuse 

 which the sea casts up, and the waste which floats 

 on its surface, are the three principal classes of the 

 food of marine birds. 



There are none of these birds which prey directly 

 upon other birds, as the accipitres do upon land ; 

 and therefore there are none of them which have 

 crooked talons or beaks like these. It is true that 

 several of the eagles fish, and, though none of them 

 refuse land prey when they can obtain it, there are 

 some which depend more on the sea than on the 

 land ; but they are land birds, clutching their prey 

 with the feet, and altogether unfit for swimming. 

 Some of the sea-birds also prowl along the shores, 

 and eat the eggs and the unfledged young of other 

 birds ; and there are some which rob others of the 

 prey they have taken, by making them disgorge it 

 from their stomachs ; these last are birds of strong 

 bill and powerful wing, but still their characters, 

 though different from those of all land-birds, resemble 

 those of the omnivora more than the accipitres. 



The birds which make the most natural transition 

 from the herons and other tribes which fish in the 

 fresh water, are those which Cuvier calls totipalms, 

 or entire-feeted, from their having all the toes in- 

 cluded in one web. These, though not the birds to 

 which the name of " sea-eagles" is usually given, are 

 the ones which in their habit much resemble the 



eagles ; they dash into the water, and seize that prey 

 which they have previously discovered by the eye, 

 only they seize it with the bill. But most, if not all 

 of them have a double habit ; as they also catch prey 

 while swimming on the surface ; but they live more 

 upon live fish, and less upon the offal of the sea than 

 most of the other races. 



The bill of the gannet, of which a figure is given, 

 may be considered as the most characteristic of these 

 bills. 



It will be seen that it is stout at the base, nearly 

 straight, has both mandibles serrated, and both tips 

 a very little bent. Its outline is that which gives the 

 greatest stiffness with the same quantity of materials ; 

 but the upper mandible, as in all bills which act very 

 powerfully, has a little motion. When the bird de- 

 scends with velocity, this bill transfixes like a spear, 



Gannet. 



and retains its hold like a barbed hook. The darter 

 and the tropical bird have their bills formed in a 

 manner similar to that of the gannet. and they also 

 dart or descend on their prey ; but the darter is a 

 more landward bird, perching on trees, and fishing 

 chiefly in the fresh waters, or in those salt lagunes 

 where there are mangroves ; and the tropical bird is 

 more discursive over the sea. 



The cormorants, which fly lower, have the bill less 

 capable of thrusting with the point, or of resisting a 

 strain on the base. Its thickness is more uniform, 

 and the upper mandible is much more hooked, while 

 the lower one is truncated, and a small portion of the 

 bill has an oblique cutting motion. There is a trace 

 of the carrion bill in it, and the mandibles are not 

 serrated. The birds which have this bill do not 

 fish in the same style as the gannets and darters. The 

 bill of the albatross, which is a very wide-ranging 

 bird, has still more of the carrion shape ; but it has 

 also a sort of tooth on the bend of the mandible, and 

 thus can lift prey out of the water. 



The true scavenger's bill on the " high seas" is that 

 of the petrels, of which the fulmar's is typical. 



The angular portion at the tip of the upper man- 

 dible of this bill, and the bend on the lower, which 

 acts against it, are both very strong and hard, so that 

 it is well-adapted for tearing the flesh of whales and 

 of the larger fishes when their carcasses float dead on 

 the sea. By that most efficient part of the bill being 

 carried at an oblique angle to the water, while the 

 bird swims or skims the surface, it can easily pick up 

 all manner of garbage, however minutely divided, 

 and even sip the oil which floats on the sea. 



The numbers of these petrels are immense, far 

 greater than those of any other birds a single flock 

 is sometimes seen as numerous as would cover the 

 M M2 



