FIELD NOTES ON ESSEX ORNITHOLOGY. 99
Here I find the birds, in the nesting season, much addicted to
perching on bare trees or stumps; and on the 18th May a bird
was actually uttering its "jick-jack" note from the branch of a
dead ash tree 30 feet from the ground. Near the same spot I
saw a Snipe forcibly knocked from its perch on an iron rail by a
smaller bird which was either a Thrush or a hen Blackbird. The
nest of the Snipe in this district is always well concealed. Since
1912 the Snipe's curious habit of flying back downwards has been
noticed on several occasions in Essex.
Sometimes we notice the purring whistle of migrant Dunlins
over Theydon, and the bird occurs also on the lake at Navestock.
A dense flock manoeuvring over the Maplin Sands on the 7th
January 1910 was, I estimated, three-eighths of a mile long. In
May of the same year, near Rainham, we watched a flock of
fifteen Dunlins in full summer livery, and I came to the con-
clusion that these belonged to the larger northern race which I
used to see on migration in the northern counties when the
resident Dunlins were already settled at their breeding stations.
In 1909, 1910 and 1911 I frequently encountered the Green
Sandpiper in Essex, chiefly in autumn, and sometimes in winter.
Along the Roding I seldom failed to see it, but latterly this
entertaining bird has seemed scarcer. At Theydon on the
30th April 1917 we saw a spring example. During a Zeppelin
raid in 1916 we startled a Green Sandpiper from the pond on
the Green at Theydon Bois, its piercing whistle (surely the
shrillest of bird voices) cutting into the low growl of the other
migrant. The same night (either August or September) there
was a considerable passage of Bar-Tailed Godwits, yapping like
puppy-dogs as they flew overhead.
The Common Sandpiper in Essex often consorts with the
Green Sandpiper, but may be recognised at once by its inveterate
bobbing as it walks. On the wing the Green Sandpiper calls
to mind a gigantic House Martin, owing to the pattern of dark
upper parts and snow-white croup.
The Redshank now breeds pretty freely down the Roding
Valley, and sometimes at Theydon Bois, where I have often seen
the birds in summer. In Essex the nests seem less concealed
than they are elsewhere. Like the Snipe, the nesting Redshank
is found perching on trees or other elevated objects.
In August one comes across the Greenshank along the Thames