===========+=============+============+==============+==============
LOCALITY | Wing | Tail |Exposed culmen| Tarsus
-----------+-------------+------------+--------------+--------------
Micronesia |203 (197-211)|83.6 (77-89)| 27.9 (26-30) |38.5 (37.5-40)
Phoenix |197 (193-203)|82.2 (79-85)| 26.3 (25-28) |37.2 (36-39)
-----------+-------------+------------+--------------+--------------
_Specimens examined._--Total number, 72 (44 males, 19 females, 9
unsexed), as follows: Palau Islands, AMNH--exact locality not
given, 64 (Oct., Nov., Dec.); Caroline Islands, AMNH--Truk, 4 (June
15, 16)--Ponapé, 3 (undated)--Kusaie, 1 (April 25).
_Nesting._--The Dusky Shearwater in Micronesia nests in holes on
high, and usually isolated, coral cliffs. Owston's collectors,
according to Hartert (1900:10), found a nest with one egg at Truk
on June 16. The nest was in a hole four feet deep in the side of a
cliff. The egg is white and measures 42 × 35. Yamashina (1932a:408)
records the taking of one egg at Arakabesan, Palau Islands, on May
26. Coultas (field notes) gives an interesting account of nesting
activities of this shearwater at the Palau Islands. He found the
bird nesting on small islands of the group from October to
December, 1931; however, he states that the natives told him that
the bird nests throughout the year. Land crabs and shearwaters were
often found together in the same burrow. Apparently the adult birds
did not remain in the burrow with the young during the day. At
Kusaie, Coultas was told by the natives that the adult birds were
caught by tying the mandibles of the young together. When the
parent birds approached and hovered over the young birds expecting
their mouths to open, the natives had the opportunity to strike
them down with clubs. Coultas collected six downy nestlings at
Palau in November and December.
_Remarks._--The first published account of this shearwater in Micronesia
was apparently by Kittlitz (1858, pt. 1:358) when he recorded his
"Schwärzlicher Sturmvogel" at Kusaie, according to Wiglesworth
(1891a:79). Finsch (1875:44 and 1881b:113, 115) studied specimens taken
by Tetens, Heinsohn, and Kubary at the Palau Islands and those taken by
Kubary at Ponapé. Earlier, Hartlaub (1868:832) used some of these
specimens from the Palau Islands to describe his _Puffinus opisthomelas_
var. _minor_, which was destined to be placed in synonymy (Murphy,
1927:10). Oustalet (1896:54, 55) recorded specimens taken by Marche at
Saipan in May, 1887, and at Rota in July, 1888. Oustalet referred to
them as _P. obscuras_ and _P. tenebrosus_, respectively. T. W. Gulick
obtained undated skins at Ponapé. Hartert (1900:10) reported on
specimens taken by Owston's collectors at Truk. In 1931, Coultas with
the Whitney South Sea Expedition took one shearwater at Kusaie and a
series of 64 skins at the Palau Islands. He failed to find birds at
Ponapé and wrote that their scarcity there may have been due to
persistent hunting of them by the inhabitants of the island. The NAMRU2
party obtained no information concerning the birds at Guam, Rota, or
Truk, but at the Palau Islands observed shearwaters at sea approximately
6 miles east of Babelthuap Island on September 2, 1945.
Murphy (1927:6-15) revised the shearwaters of the _Puffinus lherminieri_
group, and recognized several subspecies. _P. l. dichrous_ was assigned
a range consisting of Micronesia, the Phoenix Islands, and Nauru Island.
The breeding range of _P. l. polynesiae_ was given as the Samoan,
Society, Tuamotu and Marquesas islands. Color differences between the
two subspecies are very slight, and he separated them on the basis of
the length of the exposed culmen as follows: _P. l. dichrous_ 22.6-27
(26) in _P. l. polynesiae_ 25.5-30 (28.9). In other measurements they
closely resembled one another. At the time of his study, Murphy did not
have the shearwaters from Micronesia collected by Coultas and actually
did not have a large series from these islands. On studying this new
material, I find the length of the exposed culmen of 17 adult birds from
Micronesia (including 12 from the Palaus) to be 26-30 (27.9). In
comparison with Murphy's findings, my measurements of Micronesian birds
fall almost midway between the measurements which he recorded as
characteristic of _P. l. dichrous_ (from the Phoenix Islands) and _P. l.
polynesiae_. The intermediate position of the measurements of the
Micronesian birds, together with the absence of other distinguishing
characters, suggests that these shearwaters belong to only one
subspecies which consists of a group of isolated and variable
populations. Unless the old specific name, _obscuras_ of Gmelin, is
revived, the name for the entire group in Micronesia and Polynesia would
be _P. l. dichrous_. I agree with Murphy that the Bonin form, _P. l.
bannermani_, is a well-defined subspecies.
=Pterodroma rostrata rostrata= (Peale)