43(5 



B I R D. 



of a county. They ail'ord a _ very striking 

 instance of the vast productiveness of the sea ; for 

 thev, numerous as they are, are only one of the races 

 that subsist on its refuse. But when we consider tiiat 

 the sea is more than twice as extensive in surface as 

 the land, and that it is inhabited to the depth of many 

 fathom?, while the land can (as the barren places com- 

 pensate for the elevations, whether of hills or of ve- 

 getables) be reckoned only as the one surface, we are 

 within the limits when we say that the productive 

 power of the sea is a thousand times greater than 

 that of the land ; or that, if its productions could be 

 arrived at, and their nature would suit, the sea might 

 support all the life that could exist upon the land, and 

 never feel the burden. 



The storm-petrels are lighter birds, and of more 

 rapid wing than the common petrels ; but they have 

 the bill of the same form, though weaker. They 

 subsist chiefly upon the smaller garbage, and especially 

 apon oil, which they collect from the water on the 

 feathers of their breast, and then remove with the 

 bill. All the petrels have the nostrils enclosed in 

 separate tubes sometimes single, and sometimes 

 double ; but the use of these in their economy is not 

 known. 



With the storm-petrels one group of sea-birds, 

 classed according to their habits in feeding, and the 

 structure of their feeding organ, may be said to ter- 

 minate ; but there is still another, the commencement 

 of which may again be taken from the shore, and 

 traced to the more extended pastures of the other. 



The group which has now been mentioned as ex- 

 tending from the gannet to the storm-petrel inclusive, 

 may be regarded as having a relation (such a loose 

 relation of mere analogy as can exist between preyers 

 at sea and preyers on land) to the birds of prey the 

 gannets and races which have similar habits to the 

 eagles, the petrels to the vultures, and the storm- 

 petrels to the birds which catch insects on the wing. 

 The analogy is, as has been said, a loose one; but it is 

 of use in forming a relative estimate of the economy 

 of the sea and the land. 



We may, therefore, continue it with the remaining 

 sea-birds, which are principally the lestri or skuas, 

 the gulls, and the terns. These are the omnivorous 

 birds of the ocean ; but the term, as applicable to 

 that element, does not include vegetable food, though 

 many of these sea-birds feed on land, during the 

 breeding season, and also when the sea becomes too 

 stormy for them. 



The leslri, though called eagles (the real sea-eagles 

 are land-birds), are the ravens of the deep ; and in 

 their bills, their claws, and the general cast of their 

 bodies, they have a raven-like air. The following is 

 the bill of the common skua, the most typical and 

 powerful of the genus. 



Common Skua. 



'This bill is very strong, coulter-shaped, hard in its 

 texture, and considerably hooked at the tip of the 



upper mandible, though nearly straight for the greatci 

 part of its length. But it is not a murderous bill or a 

 very prehensile one. It has no tooth or notch, or 

 even the sliding motion at the point which charac- 

 terises gnawing bills. Accordingly, though the 

 skuas are strong and bold birds, they do not kill 

 lull-grown prey, neither are they very dexterous in 

 catching their own fish. They rob the m-?ts of other 

 birds, and they rob the gulls of the contents of their 

 stomachs. They are, what their systematic name 

 expresses, lestri robbers, takers of that which belongs 

 to others. They seek not the shore-bird, they seek 

 its eggs ; they seek not the sea-bird, they seek its 

 food ; and even among mankind, it has always been 

 reckoned more cowardly to attack the infants than 

 the father, and baser to injure " the means " than 

 openly attack the man. 



The gulls follow, as the rooks and crows of the sea, 

 fishing occasionally, but only for fry and the smaller 

 fishes, and living on carrion, mollusca, worms, and 

 " whatever they can find." Some of them come occa- 

 sionally on shore and clear the ploughed land of 

 larvae and worms along with the rooks ; and not a few 

 breed in small lakes and marshes many miles inland, 

 and find marsh food for themselves and their broods. 

 Their bills correspond, as may be seen in the follow- 

 ing figure. 



Common Gull. 



The terns take up the succession from the gulls ; 

 and, in the gull-billed tern, which may be considered 

 as the commencement, there is much similarity not 

 only in that organ but in the general air of the body; 

 and" as we trace them to the more typical terns, the 

 bill does not assimilate to that of the swallows (though 

 the terns have not very discerningly been called 

 " sea-swallows"), but to that of the pratincole, which 

 may perhaps be considered as the last of the 

 omnivorous feeders among the land-birds, and the 

 most powerful on the wing. And it is not a little 

 remarkable, that when this rare but beautiful stranger 

 makes a dash over from the Danube to the Hebrides 

 or Zetland, by way of a morning trip, it is found in 

 the company of gulls and terns. 



The storm-petrels are the real swallows of the sea 

 the birds which feed upon the lightest and highest 

 production of the waters, just as the swallows and 

 swifts are the last of the land tribes which feed exclu- 

 sively upon living creatures ; arid, although the food 

 is different, and requires a different form of bill, it is 

 not a little remarkable that the general structure, air, 

 and even colour of the storm-petrels, resemble those 

 of the swallow tribe ; while those of the terns have 

 more of the pratincole in them. 



Notwithstanding the length to which this part of 

 the subject has already extended, there are still some 

 very striking analogies of which it may be desirable 

 to take notice, the more especially that they have 

 not, so far as we are aware, been previously noticed 



