BIRDS OF WEST THURROCK MARSH. 263 
convenient habit of taking a short cut across the promontory, 
and it is thus easy for the ornithologist to get a good view of 
them, particularly if a strong S.W. wind is blowing. 
I once had the pleasure of noting five species in one day, viz.. 
Black-headed Gull (Larus ridibundus), Common Gull (L. canus), 
Herring Gull (L. argentatus), Lesser Black-backed Gull (L.fuscus), 
and Great Black-backed Gull ( L. mar inns). This was on a 
bitterly cold and boisterous day in January. Incidentally, I, 
would remark that the larger species of gulls appear to be more 
common at Thurrock and Purfleet in January than in any 
other month, and, providing that the weather conditions are 
as described, it is quite a common occurrence to see a fine adult 
Black-backed Gull battling its way against the wind within 
twenty yards of the observer. 
Towards evening (3.45 p.m. till dusk, in January), the interest¬ 
ing spectacle of the gulls* homeward flight may be seen from this 
point. High overhead they wing their way in extended wedge 
formation down the river to their roosting place, the larger species 
in small parties numbering from three to a dozen, and the Black¬ 
headed Gulls in bands which may number anything from twelve 
to fifty. I am of opinion that every gull haunting the river 
from Stepney to Purfleet passes over Stone Ness each evening. 
I can give no estimate of their number, but the passage of 
small parties is practically continuous during the period of 
time mentioned. 
A specimen of L. ridibundus which I examined in October 
1905, contained a great number of small crustaceans (? Gammarus 
sp.) 
In the first week of September 1905, I observed a small party 
of about a dozen Terns hovering and dipping over the water 
E. of the lighthouse. The distance was too great to admit of 
definite identification, but the call-note and actions of the birds 
were unmistakably those of Sterna. It would be interesting to 
know what they were feeding on. The Little Goby (Gobius 
minutus) and the Ditch Prawn (Palcemon varians) are invariably 
present in the little pools left by high tide on the saltings, hence 
the supposition is admissible that these ground-loving fish and 
crustaceans come to the surface of the up-flowing tide and 
possibly attract the Terns. 
I have personally noted the following ducks :—Mallard 
