724 



STERNA. 



Though there is no impulse on" the part of the tern 

 to this incubating only during the nipht and when 

 the weather is inclement, yet there is an obvious 

 purpose answered by it in nature, and this is the 

 proper lesson of wisdom for us to draw from it. 

 Where the tern breeds the pasture is rather a poor 

 one, and food, even for a small bird, cannot be ob- 

 tained without a good deal of labour. From the 

 smallness of the prey too, and the necessity of ranging 

 for it on the wing only, the clearest light is essential 

 for the feeding of the bird ; and those very circum- 

 stances of the locality which render it necessary that 

 the female tern should be abroad finding her food for 

 the greater part of the day, carry on the incubation 

 of her eggs without her assistance at the time, when 

 she is thus occupied. 



Thus, when we take a proper view of this, we come 

 to the very same conclusion to which we are led in 

 every case in nature when we take it upon its own 

 evidence, and do not call in the aid of a gratuitous 

 sort of " inferior reason," which vitiates the whole 

 case. All the birds of bare and sandy places, from 

 the ostrich on the great inland desert to the tern on 

 the shingly beach of the sea, are under the same law, 

 though that law, as well as their own organisations 

 and habits, are varied so beautifully according to the 

 circumstances, that each is the best adapted for its 

 own locality. If the bird must, according to its 

 general habits and habitation, range the w hole day in 

 feeding, the eggs are always so placed as to be 

 hatched by the sun during that time ; but to give the 

 bird credit for plan and purpose in this matter would 

 not be less absurd than to give it credit for plan and 

 purpose for having adapted the structure of its body 

 to the place which it holds in creation. Indeed, if 

 we admit the one we eventually admit the other, 

 whether we avow it in so many words or not. 



Wilson says that the eggs of the lesser tern in 

 America are generally four in number, while the 

 most careful of the British authorities say that they 

 are never more than three. This would not be a 

 ground for supposing a difference of species, because 

 the eggs of various birds are more numerous in 

 America than they are in the corresponding species 

 of Europe. This seems to arise from America being 

 better adapted for the bird. In the tern this is 

 remarkably the case, because there are many more 

 salt marshes and mud banks on the coasts of America 

 than on those of Europe. These eggs are very 

 similar in size, shape, and colour, to those that occur 

 in this country, and they are always placed higher 

 than the greatest high-water line. We must not 

 consider, however, that the bird studies their safety 

 any more than that she places them on the dry 

 surface, knowing that the sun will assist in hatching 

 them there. The birds are very clamorous, however, 

 when their breeding-ground is invaded. Wilson 

 says " During my whole stay, these birds flew in 

 crowds around me, and often within a few yards of 

 my head, squeaking like so many young pigs, which 

 their voice strikingly resembles. A humming bird, 

 that had accidentally strayed to the place, appeared 

 suddenly among this outrageous group, several of 

 whom darted eagerly at him ; but he shot like an 

 arrow from them, directing his flight straight toward 

 the ocean." The food of these birds is exclusively 

 animal insects, Crustacea, small mollusca, and all 

 the produce of the peculiar places to which they 

 resort. They feed on the wing, catching their prey 



in the air, on the ground, or in the water ; but they 

 do not walk in search of it. They can range for a 

 long time, but they are often much exhausted, and 

 remain motionless on the ground for hours together. 

 Besides having more numerous broods, the American 

 species is about an inch longer than that of the 

 eastern continent. 



AMERICAN MARSH TERN (5. aranea). This spe- 

 cies is about the same size as the gull-billed tern of 

 the eastern marshes, but it is a bird of different 

 character, more rapid on the wing, and with the bill 

 differently formed. The length of this species is 

 fourteen inches, and the stretch of the wings not less 

 than two feet ten inches ; the bill is rather stout, 

 much rounded on the culmen, and of a glossy black 

 colour ; the crown and nape are black, and the rest 

 of the upper part dull bluish white, with the shafts of 

 the quills and tail-feathers pure white ; the under 

 parts are pure white ; the tail is much forked, and 

 the closed wings extend two inches beyond it ; the 

 legs and feet are black ; the eggs are three or four 

 in number, of a greenish olive colour, spotted with 

 brown ; the young have the points of the feathers 

 on the upper part of the head white, but the basal 

 parts, as far as the black extends in the mature birds, 

 is dark coloured ; the feet are dusky orange, and 

 there are some mottlings on the tips and edges of the 

 primary quills. 



Wilson found this species on the cold marshes, 

 where the eggs were deposited on the drift grass 

 without any formal nest. The principal food appeared 

 to be a large black spider, which is abundant in these 

 situations, and moves under the water as well as in 

 the air. 



THE BLACK TERN (S. nigra) occurs in Britain, 

 but it is not a very common bird. Its breeding- 

 places are by the pools in the salt marshes, and the 

 nest is placed in the cover of reeds and other tall 

 aquatic herbage. It makes a nest, though a very 

 rude one, of dry leaves and other vegetable matter?. 

 In its dimensions it exceeds the lesser tern, though 

 not by a very great deal. In summer the upper part 

 of the body is bluish-ash, with the exception of a 

 small margin of white on the external feathers of the 

 tail ; and the nape, the chin, the throat, and all the 

 under parts, are greyish-back. The male is easily 

 distinguished at this season by a small white spot on 

 the chin, which is wanting in the female. In winter 

 all the colours of the under part fade to white, and 

 the colour on the back becomes much paler in the 

 tint. The webs of the feet are much more deeply 

 notched between the toes than those of the other 

 terns. The young have the upper part brown, with 

 the borders of the feathers paler than the rest. 

 During the breeding season these birds keep close in 

 the cover of the marsh vegetation ; but in the end of 

 summer, when their broods are matured, they di- 

 sperse along the line of the shores, the time of their 

 stay in the marshes being about three months. They 

 have been sometimes confounded with the common 

 tern, but they are a distinct species. 



THE ROSEATE TERN (S. Doitgalii). This is a larger 

 species than the preceding, and its habits are less 

 those of a marsh bird, for it is found only by the sea, 

 and in the lower estuaries of the tidal rivers, espe- 

 cially where there are flat islets and long expanses 

 of shingle and sand, without being flooded at high 

 water. It is fifteen inches in length, but has the 

 wings much shorter in proportion than most of the 



