IOO 
1 HE ESSEX NATURALIST. 
estuary, and these birds are so tame that I have been able to 
see the thickening of the leg-joint indicative of immaturity. The 
usual call of these youngsters is a tri-syllabic “ too, too, too/' 
very loud and emphatic, often heard at night during the autumn 
migration. 
For a week or more in January 1918 a single Curlew haunted 
the Sewage Farm at Theydon Bois, and I have come across the 
bird on rare occasions in other parts of inland Essex ; but, 
strangely enough, I seldom hear this species on migration over 
Theydon. The rippling whistle of the Whimbrel is not unusual 
in May, and of course I have seen this passage-bird in fair numbers 
on the fields bordering the coast. 
On the 4th May 1912 a couple of handsome Black Terns 
were hawking for (apparently) emerging caddis-flies over the 
lake at Navestock. The white patch below the tail was very 
striking against the dark plumage. 
Gulls, I think, are, considering the proximity to the sea 
and to the Thames at London, strangely rare near Theydon 
Bois, and I do not often see them. The abundance of the Greater 
Black Back along the Thames Estuary below Grays struck me 
as noteworthy in winter. 
The Little Grebe nests in some numbers at Birch Hall, 
where I have sometimes been able to watch the swift movements 
(a second’s work) by which the bird draws a concealing layer 
of rotten weeds over its eggs before leaving the nest on alarm. 
The uninformed observer would most certainly fail to recognise 
the structure then as a bird’s nest, and the bird itself is an 
accomplished hideling. A Little Grebe picked up unhurt in the 
road outside spent a few hours in my bathroom before I re¬ 
leased it. Very often it used alternate strokes of the feet in 
paddling around the bath, and on alarm its sudden change in 
draught was remarkable, the body dropping in the water as 
though it had been pulled down. 11 A piece of board was placed 
in the bath for a perch ; but when we entered the room the 
Grebe always dived under the wood, holding the top of the head 
to the nostrils above the surface of the water, and staying in this, 
position as long as we remained in the room. 
1 Zoologist, 1910, p, 201. 
