22O PATAGONIAN EXPEDITIONS: ZOOLOGY. 



Mr. Saunders, referring to the variation in size of L. dominicanus, 

 writes: "The female is smaller and has a less robust bill; there is, how- 

 ever, much individual variation irrespective of sex. For example, there is 

 as much difference between birds obtained on the Island of Kerguelen 

 alone as there is between examples from all the rest of the area frequented 

 by the species." (Cat. Bds. Brit. Mus. XXV. p. 248, 1896.) 



In "Voyage of the Beagle, Zoology," Part III. Birds, page 142 (1841), 

 Darwin writes of Larus dominicanus'. "This Gull abounds in flocks on 

 the Pampas, sometimes even as much as fifty and sixty miles inland. 

 Near Buenos Ayres, and at Bahia Blanca, it attends the slaughtering- 

 houses, and feeds, together with the Polybori and Cathartes, On the gar- 

 bage and offal. The noise which it utters is very like that of the common 

 English Gull (Larus canus, Linn.)." 



Tom Bay, Straits of Magellan: "One fine day in April we noticed a 

 great concourse of gulls and shags, attracted by a shoal of fish, in the 

 pursuit of which they ventured unusually close to the ship. This gave 

 us an opportunity of observing that the common brown gull of the chan- 

 nels, the female of L. Dominicanus, behaves towards the male bird in 

 many respects like the skua. No sooner would one of the ' black- 

 backed' (male) birds capture a fish, and rise from the surface, than he 

 would be attacked by one of the brown birds, and chased vigorously 

 about the harbour ; the predatory bird not desisting from the pursuit until 

 the coveted prize had been dropped by its rightful owner. This I noticed 

 on more occasions than one. As a rule, however, the female was content 

 to fish for herself. Several Dominican gulls in immature plumage were 

 seen amongst the crowd, and were easily distinguished from the adults 

 by the mottled brown plumage, and by the colour of the mandibles being 

 green instead of orange, as in the males, and black as in the females. 

 Now and then the whole flock of gulls and shags would rise on the wing, 

 as they lost the run of the shoal of fish. They would then be directed to 

 the new position of the shoal by the success of some straggling bird, when 

 a general rush would be made to the new hunting ground. It was most 

 amusing to witness the widely different fishing powers of the shags and 

 gulls, and the consequently unequal competition in the struggle for food. 

 The shag in flight, on observing a fish beneath him, at once checks him- 

 self by presenting the concave side of his wings to the direction in which 

 he has been moving, and then, flapping legs foremost into the water, turns 



