================+==========+=========+=========+=========
NUMBER AND SEX | Wing | Tail | Culmen | Tarsus
----------------+----------+---------+---------+---------
8 males | 103 | 91 | 27 | 26
| (98-105) | (88-93) | (26-28) | (25-27)
| | | |
6 females | 100 | 87 | 27 | 26
| (97-101) | (86-89) | (26-28) | (25-27)
----------------+----------+---------+---------+---------
_Specimens examined._--Total number, 27 (14 males, 13 females), as
follows: Caroline Islands, USNM--Truk, 2 (Feb. 16, not dated);
AMNH--Truk, 25 (Jan. 29, Feb. 1, 8, 10, 11, May 6, 9, June 11, 13,
14, 15, Oct. 11, 31, Nov. 2, 11, Dec. 3, 12, 17, 20).
_Nesting._--Yamashina (1932a:404) reports on the taking of a nest
containing one egg at Natsushima, Truk Atoll, in May, 1931.
According to Hartert (1900:5) Owston's collectors obtained nests on
June 1, 4, and 12. Two were in breadfruit trees about twenty feet
above the ground. Each nest contained one egg. Hartert writes, "The
eggs are cream-coloured, speckled with brownish red, more
frequently and often very thickly on the large end, and with some
deeper lying pale purplish grey patches, and one has some very fine
black lines on the large end."
_Molt._--A study of adult specimens obtained at various times of
the year indicates that _Metabolus_ normally molts in the period
from about October through January.
Mayr (1933e:1-10) has studied the variation of immature and adult
plumages in _Neolalage banksiana_ (Gray) and other birds pointing
out the occurrence of "retarded" and "progressive" plumages.
Bogert has followed this work in interpreting the condition of the
plumages in _Metabolus_, and through the kindness of Ernst Mayr I
have examined Bogert's unpublished manuscript on the series of
_Metabolus_ at the American Museum of Natural History, from which
the following account of the plumage is taken.
In the series of skins, there are specimens of non-molting,
immature males with "normal" plumage (that is to say, plumage with
upper parts cinnamon-colored and lower parts whitish and darker
buff) taken in October and in February. There are also specimens
of non-molting, immature females with "normal" plumage taken in
November and in May. These immatures are in fresh or slightly worn
plumages. In addition, there is one non-molting, male specimen
(November) which has some white on the crown and throat, some
black on the lores and chin, but because the black feathers are
fresh, the specimen is considered to be a "transition" bird and
may be either a "retarded" adult or a "progressive" immature male.
One non-molting female (October) shows some sooty-black mottling
on the chin and throat and a few black feathers on the crown; this
is apparently a "progressive" immature because the lower mandible
has a yellow basal part, characteristic of the immature. Another
female (June) shows black feathers on the crown, nape, chin,
throat, and breast; this bird is in the process of molting with
the black feathers representing new growth and is an immature
assuming the adult condition--in "progressive" plumage. One
non-molting male (January) has an intermingling of white feathers
in the cinnamon coloring of the head and body, black on the
forehead, chin and throat, primaries black with cinnamon edges,
and bill similar in color to that of the adult; it is considered
to be an adult with "retarded" plumage. Two molting males
(December) resemble adults except for cinnamon coloring on
shoulders, back, primaries, retrices and a slight cinnamon wash on
breast feathers; these may be "retarded" adults. One molting
female (June) has mixed cinnamon and sooty-black feathering; this
may also be a "retarded" adult. Another molting female (December)
with more sooty-black feathering and less cinnamon feathering is
also considered to be a "retarded" adult. In fully adult birds
there is considerable individual variation, especially in the
males where the amount of black on the throat, the extent of the
black on the terminal part of the primaries, and the extent of the
black on the basal part of the tail feathers is variable.
Scattered white feathers may be present on adult females.
_Remarks._--Hombron and Jacquinot first obtained the Truk Monarch, but
it was not until the time of Kubary and of the Japanese collectors of
Owston that very much was learned concerning the bird. In 1945, McElroy
of the NAMRU2 party reported that he found no birds at the several
islands of Truk that he visited in December. Some of the Japanese
residents of the islands told McElroy that they did not know the bird.
Evidently, its numbers are low or it has been eliminated, at least on
the islands then populated by the Japanese.
_Metabolus_ belongs to a group of flycatchers including the genera
_Pomarea_, _Mayrornis_, _Neolalage_, _Monarcha_, and _Clytorhynchus_.
The different plumages of the adults and the immatures are not unusual
in this group of genera, this feature being observed in many of the
flycatchers of Oceania. Mayr (1933c:1) points out some of the
relationships between _Metabolus_ and some of these other genera; he
comments that all of them have rather thin bills, in contrast to those
of other flycatchers.
_Metabolus_ became established at Truk probably as the result of an
independent colonization. It is a well differentiated genus showing
little resemblance to _Monarcha godeffroyi_ of Yap. In looking over the
genera found in the Pacific area, it appears that _Metabolus_ is closest
to _Clytorhynchus_ of the Melanesian region, especially to
_Clytorhynchus hamlini_ Mayr, which is resident at Rennell in the
Solomon Islands. The bills of these two birds are similar, both being
long and thin, with a pronounced hook. In coloration there is some
resemblance; _C. hamlini_ has the blackish forehead and chin like the
male _Metabolus_ and also the burnt-orange underparts. In _C. hamlini_,
however, the sexes are similar, _Metabolus_ also resembles _C.
nigrogularis_. Like _Metabolus_, the immatures of this latter species
are different in color from the adults.
=Monarcha godeffroyi= Hartlaub