AUSTRALIAN WHITE TERN. 
“ The usual place for the birds to lay is on a damaged place on the stem 
of a tree. These damaged places have the appearance of being caused by 
stones falling from the cliffs above. In time these stricken places become 
surrounded by a slightly raised ring of young wood or bark, so that the whole 
looks not unlike a miniature volcanic crater or a small funnel-shaped pit, with 
usually, though not always, a slightly raised rim. Somewhat similar places 
may be formed by dead branches dropping off, leaving a sort of socket. Such 
places, very common on pohutukawa trees, are no doubt formed in various 
ways, and are the chosen laying-places of about four-fifths of the White Terns. 
I have sometimes watched the birds at work on these places. They stand 
on the edge of the selected place (or pit, as I shall call it) and work round side- 
ways, advancing the right foot first and scratching at the edge of the pit with 
the left. When they have worked round five or six times they stop, take a 
step or two backwards, and carefully examine what they have done, picking 
up with their bills any bits of loose bark they may have scratched off and 
casting them away. This operation is repeated until aU the loose bark is cleared 
from the proposed laying-place. Occasionally both birds work at the pit 
together, each with its head over the other’s left shoulder ; but this is rarely 
done as the pit is usually too small for two birds to work at together. It was 
noticed that whenever an egg was found, the bark or wood about it was 
always carefuUy cleaned. 
“ Whenever the White Terns lay on a pit it is either a very large or a 
very small one. This is a rule to which there is practically no exception. 
The larger pits are never less than 8 or 10 inches in length (often they are much 
more), and any width from 1 to 6 or 8 inches. They generally have very little 
rim. They are usually sloping, and sometimes very steep. A fair number 
of birds lay in such places, but whenever they do the egg is always placed at 
some point where no rainwater can collect about it. The small hollows are, 
however, much more favoured laying-places, perhaps because they are more 
numerous ; but, in any case, two-thirds of the birds use them. These pits 
are from about half to one inch across, and usually circular, so that when the 
egg is in position, it is usually supported all round, and stands well above the 
surrounding wood or bark. I do not remember having seen an egg with more 
than about a third of its bulk below the level of the ring of bark, and generally 
it is placed much higher. In some cases the pit on which the egg is laid is^so 
small that I have actually seen the egg totter when the bird retired at my 
approach. The only reasons for the egg being placed so high, that I can at 
all understand is, firstly, to prevent any rainwater which may collect in the 
pit in heavy weather from coming in contact with the egg ; and, secondly, 
to allow the parent bird while incubating to almost — or, I believe, in most 
VOL. II. 
437 
