THE COMMON TERN. 
283 
eggs : — the latter number had not unfrequently been found by 
one of our boatmen. The spot from which one or two of the 
terns rose to-day was kept in view. On going to it the eggs 
were discovered, and they felt warmer than I thought it possible 
they could have been from the mere heat of the sun. It is com- 
monly believed at all the breeding-haunts of terns I have visited, 
that the bird never sits on its eggs during the day. Our boatmen 
admitted that although they had never seen terns leave the ground 
so that they could say they were just off their nests, yet on ob- 
serving them rise at a distance they have “ marked” the spot, and 
on going to it found their eggs. The various boatmen who have 
rowed us to the Mew Island made a similar remark. On the 16th 
of July, 1850, an intelligent boatman told us the belief here is 
that the sun incubates the eggs, which are always placed on the 
sunny side of the rocks ; he remarked that it must be so, as the 
birds do not sit on the nests by day. It is also considered that 
two birds sometimes lay in the same nest, as six eggs (twice the 
usual number) have been found together. That the birds do not 
sit on the eggs during the day, or do so very rarely, is certainly 
the case at the several islands visited by myself. If they did so, 
they would be hardly less conspicuous than “ snow upon a raven^s 
back;” and hence instinct may prompt them — in localities in 
which they are liable to be disturbed, both for their own sake 
and that of their eggs — to absent themselves from their nests 
in the day-time. 
Mr. Garrett has found terns' eggs perfectly fresh on islands in 
Strangford Lough, about or near which he did not see a tern all day. 
The S. hirundo has, however, not only been seen sitting on their 
eggs, but shot in rising from them, on bare rocky islets of Bantry 
Bay.* Several birds were observed on their nests placed on the 
short grass of the island off Islay, to be hereafter mentioned. In 
the latter locality (and probably in the other also) these birds are 
very rarely disturbed. 
In the month of June 1836 a number of specimens of the com- 
mon and arctic terns, killed on the islands of Strangford Lough, 
* Mr. G. Jackson. 
