BIRDS OF THE SOUTH ORKNEY ISLANDS 355 



The two species are never found to intermingle in the rookeries, though colonies may 

 be established adjoining one another. The Gentoo Penguin, however, establishes his 

 small settlements among rookeries of P. adeliae, and the two species live in close com- 

 pany on amicable terms. 



The Adelie Penguins leave the South Orkneys in the early part of April, and probably 

 spend the winter in a pelagic state, moving about among the ice until the following 

 spring, when they again seek their breeding haunts. During the winter a few birds are 

 nearly always present in Scotia Bay, and no doubt parties of birds come ashore to rest, 

 at times, on every landing place in the group. 



While the ' Discovery II ' was engaged in survey work round the islands several fine 

 opportunities for observing the birds swimming occurred. As the ship cruised slowly 

 along the shores, companies of swimming penguins would often remain close alongside 

 for considerable periods. From the flying bridge, in calm weather when the sea was 

 smooth, their method of swimming was well observed. As stated by Dr E. A. Wilson 

 the flippers alone are used for propellent purposes. The flippers are brought forward to 

 a position almost at right angles to the body, edged horizontally. For the backward 

 stroke, the anterior edges of the flippers are depressed, so that the flippers make an 

 angle of about 30° with the horizontal. They are then swept backward and slightly 

 downward, until they lie at an angle of about 45° with the line of the body with their 

 tips slightly depressed. A momentary pause in the stroke is noticeable here, then the 

 flippers are edged horizontally and swept to the front again for the next stroke. When 

 the birds swim rapidly the pause is so brief as to be hardly noticeable, and the flippers 

 move so fast that it is impossible to follow them, but the same process is evidently 

 carried out. This method of swimming appears to give the birds a gently undulating 

 motion in their progress under water. When they break surface for breathing, or 

 "porpoise", the last down-stroke before surfacing is apparently a strong one, and the 

 head and tail appear to be both raised until the bird comes to the surface, when they are 

 both immediately depressed. Sharp turns are carried out, apparently, with a combined 

 movement of flippers, tail, and feet, the latter acting as a rudder, and for ordinary 

 small alterations of course the tail alone is sufficient for steering. When swimming, 

 penguins carry their feet held out in line with the body, the webs partially folded in so 

 that the claws are nearly closed up on each other. Adelie Penguins often swim on the 

 surface, more frequently when near their rookeries or during rests from feeding. When 

 alarmed they can attain a good speed in the water, and can certainly move at from 10 

 to 12 m.p.h., at any rate for short distances. 



Dr Wilson has written such an excellent account of these engaging birds that little 

 more remains to be said concerning their habits. 



Pygoscelis antarctica (Forster), Ringed Penguin. (Plate X.) 



In the South Orkneys, Ringed Penguins breed in large numbers on all the islands, 

 and this group ranks with the South Shetlands and South Sandwich Islands as one of 

 the three main breeding grounds of the species. A rough census taken of the group in 



