-----------------+----+--------+-------+-------+-----------+-----------
| | | | |Exposed |
SUBSPECIES | No.| Sex | Wing | Tail |culmen | Tarsus
-----------------+----+--------+-------+-------+-----------+-----------
| | | | | |
_A. l. luscinia_ | 11 | males | 84 | 83 | 36.0 | 30.5
| | |(81-86)|(80-86)|(35.5-39.0)|(30.0-31.0)
| 1 | female | 78 | 73 | 37.0 | 28.5
| | | | | |
_A. l. syrinx_ | 31 | males | 78 | 71 | 26.5 | 26.5
| | |(76-80)|(68-75)|(25.0-27.0)|(25.0-29.0)
| 12 | females| 75 | 68 | 25.5 | 26.0
| | |(74-78)|(65-70)|(24.0-27.0)|(24.0-26.0)
-----------------+----+--------+-------+-------+-----------+-----------
Immature: Resembles adult, but upper parts duller and more brown
and less olive; underparts less yellow; wing and tail feathers
lighter brown.
_Measurements._--Measurements are listed in table 37.
_Weights._--The weights of three adult males obtained at Guam by
the NAMRU2 party are 30, 30, and 31 grams. An adult female from
Guam weighed 27 grams.
_Specimens examined._--Total number, 12 (11 males, 1 female), as
follows: Mariana Islands, USNM--Guam, 6 (June 2, 13, July 2,
18)--Saipan, 6 (Sept. 27, 30).
_Nesting._--Oustalet (1895:209) writes that Marche found nests at
Guam in June, 1887. The NAMRU2 party obtained two males with
enlarged gonads in June, 1945.
_Molt._--Specimens taken in June, July, and September are either
in worn plumage or in molt. Birds in worn plumage become a faded
straw-brown above. Oustalet apparently interpreted this coloring
of the worn plumage as a seasonal coloration.
_Food habits._--Seale (1901:53) reports that four stomachs which
he examined contained insects and larvae. Marshall (1949:21) lists
as food items: lizards, snails, spiders, and insects.
_Remarks._--The Nightingale Reed-warbler at Guam is restricted to cane
thickets and adjacent areas in and near fresh and brackish water
marshes. In 1945, the NAMRU2 party found the bird fairly numerous in
some of these habitats. Seale (1901:53) writes, "This bird is now quite
scarce on the island of Guam. It lives exclusively among the reedy
swamps, and those swamps are now being drained to make room for the
Chinaman's rice paddies." Mayr (1945a:295) also notes the rarity of the
species. As a result of the late war, the cultivation of rice was
reduced and the reed-warbler probably has been able to increase in some
of the now fallow areas. The most extensive range of this bird at Guam
is found in the Agaña Swamp, where there is a large area consisting of
thick cane. Here, and in the other large cane patches, the chief hazard
to the bird population appears to be fire. In dry periods, the entire
habitat might be easily destroyed by fire. The birds are extremely shy;
their melodious songs may be heard in the reeds, but their active
movements in the thick cane are difficult to observe. While hunting for
these birds along the edges of Agaña Swamp on June 2, the writer
observed, or located the calls of, at least six or seven individuals but
could only get within shooting range of three birds. Within the cane
thickets, these birds feed and move about near the ground or the surface
of the water. Rarely do they perch in a conspicuous manner in the upper
parts of the cover. Their color patterns blend perfectly with the
coloration of the dry cane stalks. Perhaps failure to find many of the
birds because of their secretive habits has caused many observers to
assume that the bird is near extinction. Nevertheless, it is my
contention that the bird, being restricted to these limited areas, has
never been very abundant at Guam. The absence of natural enemies,
especially snakes, may be one of the principal reasons why they have
been able to survive.
Reed-warblers were not found by the NAMRU2 party at Rota in 1945, nor
have they been reported from Tinian. Yamashina in 1942 described the
populations at Saipan and Almagan as distinct. I have not seen this
description, but on the basis of examinations of specimens from Saipan,
I can see no recognizable differences between these and birds from Guam.
=Acrocophalus luscinia syrinx= (Kittlitz)