Vol. XII. 



1912 



1 Bell, Breeding Habits of White Tern. 27 



branches, and remind one very much of larqe white butterflies. 

 They commence to lay about the loth November, from which 

 date until the end of the month most of the females lay. Some 

 seasons no eggs are found before the end of Novem_ber, in which 

 case the majority lay from between that date and the 25th 

 December. However, it is not uncommon to find eggs much earlier 

 or later than the above-mentioned dates. 



White Terns lay one egg only, always on a pohutnkawa tree 

 {Metrosideros villosa), and as far from the ground as possible. 

 Sometimes they lay on the high lateral branches of a large 

 upright tree, when two or three birds with eggs may be seen close 

 together, but on different branches, for they are not very sociable 

 birds ; but more generally they are found singly, near the tops 

 of long, thin, leaning trees, especially those leaning over a steep 

 hillside or deep gully fully exposed to the wind. It is, in fact, 

 on such trees that about three-fourths of the birds lay. They 

 make no nest of any kind, but lay their egg on the bare stem or 

 branch, wherever there is a little flat place or any inequality 

 that will keep the egg from rolling off. They almost always lay 

 on the main stem of the leaning trees, and rarely where it is less 

 than 4 or 5 inches in diameter, though I have on three or four 

 occasions seen an egg on a stem which was not more than about 

 3 inches thick. One egg was about 50 feet from the base of the 

 tree, which was not more than 18 inches in diameter. I have in my 

 possession a branch, 2 J inches only in diameter, on which I found 

 an egg. This is by far the smallest branch I have seen an egg on. 

 These birds do not seem to mind whether the branch or stem 

 on which they lay is level or not. Usually it is fairly horizontal, 

 but sometimes it is very steep, occasionally, I should say, at an 

 angle of 30° or 40°. In short, almost any place seems suitable, 

 provided there is some inequality that will prevent the egg from 

 rolling off while the tree is fairly still. Should the bird leave 

 the egg, however, when there is only a light wind blowing, the 

 egg is likely to lall. I have seen it do so sometimes. A suitable 

 place for the egg may be formed by two slight ridges running 

 somewhat spirally round the branch, in which case the egg is 

 placed between them ; or a little flat place where a branch forks 

 laterally is sometimes used ; or the egg may be laid on the side 

 of a stem or branch, and merely supported by a bit of stout bark. 

 Once I noticed an egg placed between a strip of bark and the side 

 of a thin stem. The strip of bark was about 18 inches long and 

 ih inches wide. It was attached to the stem at one end only, 

 the other being about 3 inches clear. The egg was placed about 

 6 inches from the secured end, where there was a gap between the 

 bark and the stem of fully half an inch. I could give many other 

 cases of finding eggs in most precarious positions. 



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 



