76 THE NIDOLOGIST 
Petrels of Sitka, Alaska. 
BY JOSEPH GRINNELL. 
T. LAZARIA ISLAND lies within the 
S limits of Sitka Bay, about twenty miles 
southwest of the capital of Alaska. It 
is irregularly shaped, approximately a 
quarter of a mile in length, by three hun- 
dred yards in width at its widest portion. 
It has the general outline of a huge rock 
with steep sides, but in the main it is 
crowned by a heavy growth of large firs 
and hemlocks. ‘There is a rank growth of 
tall grass on those parts where there are 
few trees or none at all, and among the 
trees there are scattered clumps of salmon- 
berry bushes, while the porous sod is car- 
peted by deer’s feet and other low plants. 
This island is the one in the vicinity of 
Sitka chosen by thousands of sea-birds for 
a breeding ground. The exposed, broken 
precipitous sides of the island are the re- 
sorts of the Violet green Cormorants, Pig- 
eon Guillemots and California Murres, 
while the Glaucus- winged Gulls and Tufted 
Puffins select the grassy banks and promon- 
tories above the cliffs. But the Petrels, to 
be considered in the present paper, seem to 
prefer the dark forest, although their bur- 
rows are abundant wherever there is 
enough soil to hold them. 
I found two species of Petrel inhabiting 
St. Lazaria Island, Leach’s Petrel ( Oceano- 
droma leucorhoa),and the Fork-tailed Petrel 
(Oceanodroma furcata.) The former out- 
numbered the latter fully five to one, but 
even the Fork-tails were present in thous- 
ands. 
On first visiting the island, I had no idea 
that there were besides the conspicuous 
Puffins, Cormorants and the like, other 
avian inhabitants, and being unacquainted 
with the nocturnal habits of Petrels, it was 
only by chance that I discovered them, 
though they outnumbered the other birds 
many times over. In climbing to the top 
of the island, to which I was attracted by 
a shy flock of Crossbills, my feet frequently 
crushed through the sod into subterranean 
cavities. In one instance as my foot went 
deeper than usual there was a smothered 
squeal, and it soon dawned on me that the 
ground was inhabited by some kind of 
animal, not one of which was to be seen 
above ground. ‘The sod was light and 
flaky, and I had soon laid open several of 
the Petrel burrows, disclosing their be- 
wildered inhabitants. On being handled, 
both species of Petrel disgorged large quan- 
tities of the yellowish oil with a musky 
odor, so characteristic of this family. This 
oil rapidly saturated the plumage of the 
head and breast, and the birds had to be 
caught and killed with great care or else 
they became almost spoiled for specimens. 
I finally found that the best way to manage 
them was to hold them head downward 
until they had vomited most of their oil, 
then to kill them by compressing the thorax, 
plugging the bill and throat with a copious 
amount of the damp soil. If cotton plugs 
or corn meal were used, the oil soon sat- 
urated them and spread out over the feath- 
ers.* Even the young barely out of the 
shell, although I am sure they had not as 
yet been fed by their parents, had a good 
supply of the oil. 
Most of the burrows each contained an 
gg, in which case one bird, either male or 
female, was sitting. In case there was a 
young one, neither parent bird was present. 
When there were neither egg nor young in 
the hole, both old birds were at home to- 
gether. 
On June 17 the eggs of Leach’s Petrel 
were all fresh, but those of the Fork- 
tailed Petrel were nearly hatched, and 
several young of the latter were found. On 
July 7 the lLeach’s Petrels’ eggs were 
nearly hatched and a few newly-hatched 
young were found. Thus the incubation 
period of O. deucorhoais about twenty days. 
Of course these last statements are based 
on the majority of nests examined. I col- 
lected a few nearly fresh eggs of both 
species on the latter date. The young are 
puffy balls of down, those of Leach’s being 
dark slaty, while the young Fork-tails are 
light gray. The down js superabundant, 
and the young of the age of about two 
weeks are much bulkier than the adults. 
The feathers grow from the same follicles 
as the down, and in continuation with the 
latter. As the juvenile grows larger, the 
down wears off from the ends of the feathers 
and thus gradually disappears so that finally 
hardly a trace is left. This wearing away 
of the down is first noticable on the wings, 
back and breast, and is due to the bird’s 
movements in the narrow nest-cavity. I 
took specimens that showed this process 
plainly. 
The two species of Petrel possessed the 
same nesting habits. The entrance to the 
burrows are semi-circular and usually open 
out under some clump of grass or a bunch 
