138 THE ESSEX NATURALIST.
Commenting on the above observation, Mr. E. W. H. Blagg
suggests that the wood pigeon probably casts pellets only at
certain seasons of the year, when it has been feeding upon certain
kinds of food. He adds: "A few days ago (May 14th), I found
several 'castings' of this bird, composed chiefly of the husks of
oats."92
A pellet of this bird in the Essex Museum, picked up from
beneath a roosting tree, in March 1910, is made up entirely of
seeds of Holly.
Curlew.
Mr. R. Elmhirst, in 1915, described how he found, on a
favourite roosting-place of Curlews, numerous pellets, composed
chiefly of fragments of quartz and shells, which he reasonably
assumed to be castings of this bird. He describes them as "about
one inch long by half an inch broad, and consisting of 30 to 40
small bits of quartz, and weighing about four grains: some of
them contain a few bits of shell, and one consists almost entirely
of shell."93
Mr. J. E. Harting records that he extracted cockles of large
size, with the shells unbroken, from the stomach of a Curlew,
and he wondered how they could possibly have been swallowed
whole.94 Specimens of entire shells of Cardium taken by Mr.
Harting from a Curlew's stomach are in the Essex Museum,
the size of the largest being 22 mm. by 20 mm., and another
measuring 20 mm. by 18 mm.
Terns.
Mr. H. W. Robinson states: "I have studied very carefully
the food of Terns, and handled over two thousand young ones,
the majority of which regurgitated the contents of their crops.
The chief food of the common Tern consists of young herrings,
with a fair number of whiting, and also a few young codling,
lumpsuckers, and long rough dabs." (In Yorkshire Post, quoted
in Naturalist, July 1, 1920, p. 208). Mr. Robinson does not
say, however, if this regurgitated food takes the form of pellets.
Black-Headed Gull.
Pellets of this species are of common occurrence on the
feeding-spots. Useful testimony to the beneficial character of
92 Ibid. p. 236.
93 Zoologist, 1915, p. 71.
94 Zoologist, 1884, p. 68.