124 CALIFORNIA ACADEMY OF SCIENCES [Proc. 4TH Ser. 
of the year. Perhaps there are two distinct breeding sea- 
sons, some birds laying in winter, others in summer. 
At Hood Island, quoting in substance from Mr. Gifford’s 
notes, they nested in small tunnel-like holes in the lava sea 
cliffs. The lowest holes were near the water and were damp, 
and the highest were sixty or seventy feet above it. As in 
some other petrels, the male and female become tenants be- 
fore the laying of the single egg, which is placed at the far- 
ther end of the hole, usually on the bare soil or rock, some- 
times within arm’s reach of the entrance. | 
These shearwaters are generally silent. However, on two 
occasions in January small flocks were flying about the cliffs 
at Academy Bay, Indefatigable Island, making a twittering 
sound. One evening near Essex Point, Albemarle Island, a 
flock of about a hundred was fishing. There was great ex- 
citement among them. Rushing madly about, they kept up a 
continual twittering. Twice at Hood Island, birds in their 
nesting holes were heard uttering notes somewhat resembling 
the mew of a kitten. In each instance the hole was tenanted 
by a pair of birds. These mewing notes, or one or two 
short shrill notes, were sometimes uttered when the collector's 
hand was thrust into the hole, which intrusion was always 
resented, a spirited defense being made with bill and claws. 
They showed a disposition to bully other birds. One was seen 
pursuing a Turnstone and several pestered a Brown Pelican 
until he retreated to a cliff to escape from the annoyance. 
Like some others of their tribe, they were sociably 1n- 
clined, frequently flying about the cliffs and rocks in small 
compact companies or congregating on the water or winging 
their way at times over its surface in loose flocks and strag- 
gling columns. When fishing, a community of interests was 
often formed with other species, particularly the Noddy and 
boobies. 
The flight is usually low and somewhat undulatory, as- 
cendant during the rapid wing strokes (which vary from four 
or five to eight or ten) and descendant during the short sail. 
In rough weather they rise higher and prolong the sailing 
flight, but do not attain to the “beautiful evolutions” of the 
Dark-rumped Petrel. In rising from a calm sea, they extend 
their wings and paddle rapidly forward for about two feet 
