70 
Some Piinjah Blver Birds. 
The measurement of 9 eggs yields the following results: 
lengtn from 39.4 to 42.5 mm. Breadth, from 28.1 to 31 
mm. Average dimensions, 41.8 x 29. G mm. 
A more interesting Tern than Sterna acena is the 
Black-bellied Tern, Sterna melaiwgastcr, Temm., which is 
perhaps- the commonest Tern of the Punjab waterways- -at 
any rate the most generally distributed both in time and 
place. Yet for some reason I have found it much more dilH- 
cult to secure eggs of this species than of the others — 
though I have found numbers of nests either empty or with 
young. 
It nests in company with other Terns and Pratincoles, 
or in small colonies of its own, or else alone; and is jnost 
courageous in defence of its young, making tremendous stoops 
at an intruder, often passing within a foot or two of his 
head. In fact a rough guide to the whereabouts of the bird's 
nest is obtained from the vehemence of the bird's attacks, 
which become more violent as the nest is more closely ap- 
proached. 
As far as I can make out the bird is probably in 
some degree a migrant, but as it is equally common at all 
times of the year it is difficult to define the extent to which 
it is migratory. Yet the presence of flocks at certain limes 
and places in addition to the ordinary population clearly points 
to some form of migratory movement being in progress. 
It is a great wanderer and soon finds out and visits any 
patch of water^ even a small temporary flood, miles away 
from permanent ponds or waterways. 
The nest in this species is a plain hollow, scooped 
in the sand without any use of materials. Three eggs seem to 
forni the normal clutch. The eggs are of the typical Tern 
colouration, but the shape is rather more elongated than those 
of Stenw, aeeiia. They are laid in April and May. 
The measurements of two eggs are as follows : — 34.0 
x 25.5; 32.5 x 26.5 mm. 
This Tern is most distinctive in appearance, owing 
to the sooty black of the undcrparts. It is thus described' 
{loc. cit. Vol. IV., p. 316).* 
Forehead, crown, and nape, with the sides of the huad down to 
tlu; lowi i- edge or the orbit, blaeli ; very often the oxtrcni'' I)as(; 
of the forehead is white like the lores, ehin, and throat ; upper parts 
* "Fauna of British India." 
