Acrocephalus luscinia luscinia(Quoy and Gaimard)

Thryothorus lusciniusQuoy and Gaimard, Voy. "l'Astrolabe," Zool., 1, 1830, p. 202, pl. 5, fig. 2. (Type locality, Marian Is. = Guam.)

Sylvia syrinxKittlitz (part), Obser. Zool., in Lutké, Voy. "Le Seniavine," 3, 1836, p. 306 (Guahan);idem(part), Denkw. Reise russ. Amer. Micron. und Kamchat., 2, 1858, p. 141 (Guaham).

Tatare lusciniaGray, Genera Birds, 3, 1849, App. 8 (Marian Is. = Guam); Hartlaub, Journ. f. Ornith., 1854, p. 167 (Mariannen = Guam); Gray, Cat. Birds Trop. Is. Pacific Ocean, 1859, p. 14 (Ladrone or Marian Is. = Guam); Finsch, Journ. Mus. Godeffroy, 12, 1876, p. 31 (Guaham); Wiglesworth, Abhandl. und Ber. Zool. Mus. Dresden, no. 6, 1890-1891 (1891), p. 41 (Guam); Büttikofer, Notes Leyden Mus., 14, 1892, p. 16 (Guam); Oustalet, Nouv. Arch. Mus. Hist. Nat. Paris, (3), 7, 1895, p. 209 (Guam).

Tatare lusciniusBonaparte, Consp. Avium, 1, 1850, p. 224 (Guam);idem, Comptes Rendus Acad. Sci. Paris, 41, 1855, p. 1111 (Mariannes = Guam); Gray, Hand-list Birds, 1, 1869, p. 194 (Ladrone = Guam).

Hybristes[luscinia] Reichenbach, Syst. Avium, 1850, pl. 57, fig. 7 (no locality = Guam).

Acrocephalus orientalisPelzeln, Reise, "Novara," Vögel, 1865, p. 64 (Guaham).

Tatares lusciniusGiebel, Thes. Ornith., 3, 1877, p. 599 (Marianae).

Acrocephalus mariannaeTristram, Ibis, 1883, p. 45 (Type locality, Guam).

Tatare mariannaeSharpe, Cat. Birds British Mus., 7, 1883, p. 528 (Marianne = Guam); Oustalet, Le Nat., 1889, p. 260 (Mariannes = Guam).

Acrocephalus lusciniaHartert, Novit. Zool., 5, 1898, p. 57 (Guam, Saipan); Seale, Occ. Papers Bernice P. Bishop Mus., 1, 1901, p. 53 (Guam, Saipan); Matschie, Journ. f. Ornith., 1901, pp. 112, 113 (Guam, Saipan); Safford, Osprey, 1902, p. 69 (Guam); Dubois, Syn. Avium, 1, 1902, p. 369 (Marianne); Safford, Amer. Anthro., 4, 1902, p. 711 (Guam);idem, The Plant World, 7, 1904, p. 264 (Guam);idem, Contr. U. S. Nat. Herb., 9, 1905, pp. 30, 79 (Guam); Reichenow, Die Vögel, 2, 1914, p. 545 (Marianen); Cox, Island of Guam, 1917, p. 21 (Guam); Kuroda, in Momiyama, Birds Micronesia, 1922, p. 67 (Guam, Saipan); Bryan, Guam Rec., vol. 13, no. 2, 1936, p. 25 (Guam); Thompson, Guam and its people, 1942, p. 23 (Guam); Strophlet, Auk, 1946, p. 539 (Guam).

Conopoderas lusciniaMathews, Syst. Avium Australasianarum, 2, 1930, p. 594 (Marianas); Hand-list Japanese Birds, rev., 1932, p. 177 (Marianas).

Conopoderas luscinia hivaeYamashina, Bull. Biogeogr. Soc. Japan, 12, 1942, p. 81 (Type locality, Saipan); Hand-list Japanese Birds, 3d ed., 1942, p. 196 (Almagan, Saipan).

Conopoderas luscinia lusciniaHand-list Japanese Birds, 3d ed., 1942, p. 197 (Guam).

Acrocephalus luscinia lusciniaMayr (part), Birds Southwest Pacific, 1945, p. 294 (Guam, Saipan, Almagan); Stott, Auk, 1947, p. 526 (Saipan); Baker, Smithson. Misc. Coll., vol. 107, no. 15, 1948, p. 67 (Guam).

Geographic range.—Micronesia: Mariana Islands—Guam, Saipan, Almagan.

Character.—Adult: A rather large warbler with long, curved bill; upper parts near "Saccardo olive"; feathers of head grayer because of darker shafts; rump paler and browner; lores dark; supraloral stripe light buffy-yellow; auriculars, cheeks, and sides of neck slightly darker; chin, throat, breast, and abdomen pale buffy-yellow; tibia darker and more olivaceous-brown; under tail-coverts pale yellow-buff; wing and tail feathers brown, edged with ochraceous; under wing grayish, inner edges lighter; axillaries pinkish-white; upper mandible dark horn colored; lower mandible lighter yellow; feet light gray; iris brown. Female resembles male but is slightly smaller.

Table 37. Measurements ofAcrocephalus luscinia

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 intable 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 manyobservers 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.

Sylvia syrinxKittlitz, Mém. Acad. Imp. Sci. St. Petersbourg, 2, 1835, p. 6, pl. 8. (Type locality, Lugunor and Ulcei = Woleai.)

Sylvia syrinxKittlitz (part), Obser. Zool., in Lutké, Voy. "Le Séniavine," 3, 1836, p. 297 (Lougounor);idem, Denkw. Reise russ. Amer. Micron. und Kamchat., 2, 1858, p. 92 (Ualan, Lugunor, Ulea).

EparnetesReichenbach, Syst. Avium, 1850, pl. 57 (no locality = Carolines); Bonaparte, Comptes Rendus Acad. Sci. Paris, 41, 1855, p. 1111 (Carolines).

Tatare syrinxHartlaub, Archiv f. Naturgesch., 18, 1852, p. 131 (Ualan, Lugunor); Pucheran, Voy. Pôle Sud, 3, 1853, p. 92 (Hogoleu = Truk); Hartlaub, Journ. f. Ornith., 1854, pp. 164, 168 (Hogoleu); Gray, Cat. Birds Trop. Is. Pacific Ocean, 1859, p. 14 (Ualan); Sharpe, Cat. Birds British Mus., 7, 1883, p. 527 (Carolines); Wiglesworth, Abhandl. und Ber. Zool. Mus. Dresden, no. 6, 1890-1891 (1891), p. 41 (Ruk, Ualan, Luganor, Uleei, Nukuor, Ponapé); Oustalet (part), Nouv. Arch. Mus. Hist. Nat. Paris, (3), 7, 1895, p. 210 (Ruk, Ponapi, Mortlock, Kusaie, Uleei, Nukuor).

Acrocephalus orientalisPelzeln, Reise "Novara," Vögel, 1865, pp. 63, 162 (Puynipet, Lugunor, Ulcei).

Calamodyta syrinxGray, Hand-list Birds, 1, 1869, p. 208 (Ualan); Giebel, Thes. Ornith., 1, 1872, p. 529 (Carolin.).

Calamoherpe syrinxFinsch, Journ. Mus. Godeffroy, 12, 1876, p. 17 (Ponapé, Lugunor, Ruck, Ualan, Uleei);idem, Proc. Zool. Soc. London, 1877 (1878), p. 778 (Ponapé);idem, Journ. f. Ornith, 1880, pp. 287, 297 (Ponapé, Ruck, Mortlocks, Kuschai);idem, Proc. Zool. Soc. London, 1880, p. 575 (Ruk, Ponapé);idem, Ibis, 1881, pp. 108, 112, 115, 247 (Kuschai, Ruck, Ponapé, Mortlocks); Schmeltz and Krause, Ethnogr. Abth. Mus. Godeffroy, 1881, pp. 298, 330, 353 (Ponapé, Mortlocks, Nukor, Ruk); Finsch, Ibis, 1883, p. 143 (Ruck);idem, Mitth. Ornith. Ver. Wien, 1884, p. 49 (Ponapé);idem, Sammlung wissensch. Vorträge, 14 ser., 1900, p. 659 (Carolinen).

Acrocephalus syrinxSeebohm, Cat. Birds British Mus., 5, 1881, p. 100 (Ponapé); Tristram, Ibis, 1883, p. 44 (Ponapé, Ruk, Mortlock, Lugunor, Uleei);idem, Cat. Birds, 1889, p. 152 (Ponape, Ruk); Nehrkorn, Kat. Eiers., 1899, p. 33 (Ponapé, Ruk); Hartert (part), Novit. Zool., 5, 1898, p. 58 (Carolines);idem, Novit. Zool., 7, 1900, p. 3 (Ruk); Seale (part), Occ. Papers Bernice P. Bishop Mus., 1, 1901, p. 53 (Ponapé); Matschie, Journ. f. Ornith., 1900, pp. 112, 113 (Ruk, Ponapé, Ualan); Dubois, Syn. Avium, 1, 1902, p. 369 (Ponapé); Reichenow, Die Vögel, 2, 1914, p. 545 (Ponapé); Takatsukasa and Kuroda, Tori, 1, 1915, p. 54 (Ponapé, Ruk); Mayr, Proc. 6th Pacific Sci. Congr., 4, 1941, p. 204 (Ponapé).

Conopoderas syrinxWetmore, in Townsend and Wetmore, Bull. Mus. Comp. Zoöl., 63, 1919, p. 214 (Ponapé, Truk); Takatsukasa and Yamashina, Dobotsu. Zasshi, 43, 1931, p. 485 (Caroline Is.); Yamashina, Tori, 7, 1932, p. 405 (Ponapé); Hand-list Japanese Birds, rev., 1932, p. 177 (Carolines).

Acrocephalus stentoreus syrinxKuroda (part), in Momiyama, Birds Micronesia, 1922, p. 67 (Ruk, Ualan, Lugunor, Wolea, Nukuoro, Ponapé).

Conopoderas luscinia syrinx, Hand-list Japanese Birds, 3d ed., 1942, p. 197 (Wolea, Lamotrek, Truk, Lukunor, Nukuoro, Ponapé, Kusaie).

Acrocephalus luscinia syrinxMayr, Birds Southwest Pacific, 1945, p. 294 (Carolines); Baker, Smithson. Misc. Coll., vol. 107, no. 15, 1948, p. 67 (Truk).

Geographic range.—Micronesia: Caroline Islands—Woleai, Lamotrek, Truk, Lukunor, Nukuoro, Ponapé, Kusaie.

Characters.—Adult: ResemblesA. l. luscinia, but smaller; with shorter, straighter bill; head and neck more reddish-brown; back, rump, wing, and tail edged with cinnamon; flight feathers faintly tipped with white.

Immature: Resembles adult, but lighter and more rufous in color; wings and rump paler, wings edged with rufous buff.

Measurements.—Measurements are listed intable 37.

Specimens examined.—Total number, 62 (35 males, 20 females, 7 unsexed), as follows: Caroline Islands, USNM—Ponapé, 1 (Feb. 12)—Truk, 4 (Feb. 16, Mar. 15); AMNH—Ponapé, 35 (Nov., Dec.)—Truk, 22 (Feb., March, May, June, Nov.).

Nesting.—Birds nest in reedy swamps and scrub vegetation in the Caroline Islands, although Finsch (1881b:115), recording a field note by Kubary, states that nests were found in trees at Mortlock Atoll (= Lukunor). Yamashina (1932a:405) reports the collecting of seven sets of eggs at Ponapé in July and August, 1931. The sets consisted of one or two eggs each. McElroy of the NAMRU2 party obtained specimens with enlarged gonads at Truk in December and noted that birds were carrying nest materials to cane swamps. Of the birds secured by Coultas in November and December at Ponapé, only a small number had enlarged gonads. He also found nests containing no eggs in low bushes at Ponapé. Hartert (1900:3) reports that at Truk Owston's Japanese collectors obtained "many nests" from the end of May to the beginning of July. These nests contained one or two eggs and were found 7 to 20 feet above the ground in breadfruit, coconut and ivory-nut palm trees. Hartert writes, "The eggs are white, covered with darker and lighter brown patches, and underlying ashy grey or lavender-grey spots. These spots are generally thicker near the broad end, sometimes forming a loose ring, and they are sometimes equally spread over the whole surface." He lists measurements of 48 eggs.

Molt.—Of the specimens examined by me, those taken in the spring and summer are in fresh or worn plumage; those taken in fall and winter are in molt, with a few skins exhibiting worn or fresh plumage in the latter period. Apparently the peak in the molting process occurs from September to December.

Food habits.—The reed-warbler is an insect feeder. Coultas, in his observations of the bird at Ponapé, relates that he was able to locate the warbler by listening for the "snapping of the mandibles as the bird is catching food."

Remarks.—From the observations of Kittlitz, Kubary, Coultas, McElroy, and others, it is apparent that the Nightingale Reed-warbler in the Caroline Islands is restricted to the lower elevations of the islands. Whereas the reed-warbler at Guam seems closely associated with cane swamps and adjacent vegetation, the bird in the Carolines may range more extensively into brush lands, forest marginand grass lands. Coultas (field notes) notes that the reed-warbler at Ponapé is a "common bird of the small bush and grasslands. One is attracted by its warbler-like song. The bird spends hours perched on a stem of a bush caroling the time of day. When feeding, one finds it on the ground or working away quietly among the bushes.Acrocephalusis a friendly bird who does not become frightened easily. He responds to man-made calls."

The Nightingale Reed-warbler is found on many of the islands in the Caroline Chain, including both the "high" volcanic islands (Ponapé and Truk) and the "low" coral islands (Lukunor and Nukunor). Although the bird has been recorded at Kusaie by Kittlitz and Finsch, it was not taken there by Coultas in 1931. Reed-warblers are unknown at Yap, Ulithi, Fais or at other islands of the extreme western Carolines, or in the Palau Archipelago.

They are unrecorded also in the Marshall Islands, but at Nauru in the Gilbert Islands, to the southeast, an isolated population of this bird occurs and has been namedA. l. rehsei(Finsch).

Conopoderas yamashinaeTakatsukasa, Dobutsu. Zasshi, 43, 1931, p. 485. (Type locality, Pagan.)

Tatare syrinxOustalet (part), Nouv. Arch. Mus. Hist. Nat. Paris, (3), 7, 1895, p. 210 (Pagan).

Acrocephalus syrinxHartert (part), Novit. Zool., 5, 1898, p. 58 (Pagan); Seale (part), Occ. Papers Bernice P. Bishop Mus., 1, 1901, p. 53 (Pagan).

Acrocephalus stentoreus syrinxKuroda (part), in Momiyama, Birds Micronesia, 1922, p. 67 (Pagan).

Conopoderas yamashinae, Hand-list Japanese Birds, rev., 1932, p. 177 (Pagan).

Conopoderas luscinia yamashinaeHand-list Japanese Birds, 3d ed., 1942, p. 196 (Pagan).

Acrocephalus luscinia yamashinaeMayr, Birds Southwest Pacific, 1945, p. 294 (Pagan).

Geographic range.—Micronesia: Mariana Islands—Pagan.

Characters.—ResemblesA. l. syrinx, but duller and more brownish and less olive-rufous on back, rump and tail; bill shorter and more curved.

Takatsukasa (1931:485) gives the following description: "Upperparts dark olive brown, paler on the lower rump; remiges and rectrices dark olive-brown, margined with brown. Superciliary stripe distinct and buff; chin, throat, breast and abdomen pale brown; ear-coverts, sides of neck, sides of breast and flanks dusty greyish brown, belly and under tail-coverts pale buff. Bill clove brown, legs grey, and iris Van Dyke brown." He continues, "It differs fromConopoderas syrinxof Caroline Islands by its colouration and the shape of the bill, namely in the new form the culmen is more curved and more stout, and the tail is less roundish and nearly square."

Measurements.—Takatsukasa and Yamashina (1931b:485) lists the following measurements: 13 adult males—wing, 75-80; tail, 65-70; culmen, 20-22; 6 adult females—wing, 73-77; tail, 60-65; culmen, 20-22.

Mayr examined seven specimens from Pagan in the Paris Museum. His measurements are: five males—wing, 76-79; tail, 66-69; bill from nostril, 14-14.5; two females—wing, 75, 77; tail, 66, 67; bill from nostril, 14.5, 15.

Remarks.—No specimens have been examined by me. Oustalet (1895:210) was the first to note the difference between the reed-warblers from Pagan and those from Guam and Saipan (A. l. luscinia). He regarded those from Pagan as similar to the population in the Carolines, calling themTatare syrinx. Hartert, Seale, and Momiyama followed Oustalet in this regard, and it was not until 1931 that the population at Pagan was recognized as distinct, when further collections were made by the Japanese.

Conopoderas luscinia nijoiYamashina, Tori, 10, 1940, p. 674. (Type locality, Agiguan.)

Conopoderas luscinia nijoiHand-list Japanese Birds, 3d ed., 1942, p. 196 (Agiguan).

Acrocephalus luscinia lusciniaMayr (part), Birds Southwest Pacific, 1945, p. 294 (Agiguan).

Geographic range.—Micronesia: Mariana Islands—Agiguan.

Characters.—Adult: ResemblesA. l. luscinia, but with shorter bill. Yamashina (1940:674) describes the birds as, "upper parts much less rusty in colour and the flanks and bellies are darker and more brownish than those of the specimens from Almagan and Saipan."

Measurements.—Yamashina (1940:674) gives the measurements of five adult birds from Agiguan as: exposed culmen 27-29, bill from nostril 17.0-20.0; as compared with 27 adult birds from Almagan and Saipan as: exposed culmen 30-34, bill from nostril 21.2-24.5.

Remarks.—No specimens have been examined by me. The island of Agiguan is a very small one lying offshore from Tinian and not far from Saipan, whereA. l. lusciniaoccurs.A. l. nijoiis given tentative recognition, on the basis of the measurements of the five adult specimens given by Yamashina. These indicate that the population has a distinctly shorter bill.

Evolutionary history of Acrocephalus luscinia.—The species ofAcrocephalusin Micronesia and Polynesia have received several taxonomic treatments. In regard to the Micronesian forms, Quoy and Gaimard called the population at GuamThryothoruswhile Kittlitz called the population in the Carolines,Sylvia. Evidently to emphasize the distinctness of these two birds, Reichenbach in 1850 renamed the bird in the Marianas asHybristesand the bird in the Carolines asEparnetes. The birds were later placed in the genus,Tatare, by Hartlaub, Gray, Sharpe and other workers. Gray also used the name,Calamodyta, for the bird in the Carolines.The generic term,Calamoherpe, was employed also by a number of workers for the Caroline population. Sharpe (1883:525) placed the reed-warblers in the family Timelidae and retained the name,Tatare, for the Micronesian and Polynesian forms. In distinguishingAcrocephalusfromTatarehe has the following to say ofAcrocephalus: "besides having a much shorter bill, possesses a very much more pointed wing, the distance between the primaries and the secondaries being much more than the length of the hind toe and claw; whereas inTatarethe wing is much more obtuse, and the distance between the primaries and the secondaries is less than the length of the hind toe and claw." More recent authors have followed Sharpe using the generic name,Conopoderas(=Tatare, old name preoccupied). However, Tristram (1883:38-46) regarded the separation of these oceanic forms fromAcrocephalusas a taxonomic error. He said that this is "one of the very few links (the others being the solitaryHirundo tahiticaand the Merulae) between the avifauna of Oceania and our own; and it has a much wider range east and west than either of the other links, extending from the Carolines in the east to the Marquesas in the west." Mayr has pointed out (orally to the writer) that the separation of the Oceanic reed-warblers fromAcrocephalusis an unnatural one, although it is perfectly true that the extreme members (A. caffraandA. l. luscinia) have a very long bill, but forms with shorter bills likeA. l. syrinxpoint to the close affinity between the continental species and these insular birds. This has also been noted by Hartert (1898:58). Mayr (in litt.) comments that "There is no difference betweenAcrocephalusandConopoderasin regard to the wing formula, provided that we compare the Polynesian species with the tropical forms ofAcrocephalus(such astoxopeiandcervinus). The character mentioned by Sharpe is very artificial and merely indicates the difference in the wing between a migrant of the temperate zone and a resident of the tropics. There is no denying that some of the warblers of eastern Polynesia are no longer reed-warblers but have become dwellers of trees and bushes. However, this same tendency prevails among some of the unquestionable species ofAcrocephalus(scirpaceusandpalustris) and at any rate a slight change in habits is not sufficient for generic separation." Earlier, Mayr (1942b:169) usedConopoderasas one of the several genera that is based on "morphologically distinct geographic forms." The degree of modification that has occurred in these oceanic reed-warblers, would, if the birds were in a continental area, undoubtedly be consideredworthy of specific or even generic rank by some authors; however, as Mayr (1942b:162) points out, "the majority of well-isolated subspecies have all the characters of good species and are indeed considered to be such by the more conservative systematists." Owing to their differentiation, the Micronesian and Polynesian reed-warblers might not be considered by some ornithologists as belonging to a single superspecies; however, all evidence seems to point to the origin of this group by a single invasion from Asia."

Tristram (1883:41) was the first worker to recognize the relationship of the Micronesian and Polynesian reed-warblers to the continental forms, when he placed them within the genusAcrocephalus. Rothschild (1893:2) further stated, "Tatarecannot be separated generically fromAcrocephalus." In discussing the status of the Hawaiian species,A. familiaris, Hartert (1898:58) also follows this treatment. Bryan (1941:187) also comments on the relationship of the "miller" birds of Laysan and Nihoa to species at Guam, Christmas and other islands of the Pacific.

The reed-warblers of Polynesia and Micronesia represent an ancient invasion from Asia. The continental form,Acrocephalus arundinaceous, is apparently closest to the ancestral stock of these oceanic birds. This species resembles the oceanic populations in size, general coloring, shape of bill, and wing and tail structure. Some of the continental races of this species have a shorter first primary which is similar to that in the oceanic forms. How rapid the spread was of the reed warbler through the large insular area that it now occupies is unknown.A. syrinxof Micronesia has a shortened wing and some populations have a long bill. Species in Polynesia have stronger wings than the one in Micronesia, but have become differentiated in other ways, as, for example, by the long bill ofA. caffraand the small size ofA. aequinoctialis. In addition, call notes have become varied, as noted by Chapin (in Mayr, 1942b:54). Also certain of the reed-warblers have become bush and tree-living birds. The Hawaiian birds are reduced in size and have become tree-living in a manner similar to that of other Polynesian species. These modifications of the reed-warblers of the Oceanic area appear, according to Murphy and Mathews (1929), to indicate their long-time residence in the islands, as compared with subspecies ofA. arundinaceousthat are found in Melanesia. The latter birds, which are not ancestral to the Polynesian birds, resemble closely their Asiatic ancestors and have also retained their swamp-living habits. This would seem to indicate that the birds in Melanesia may be of morerecent occurrence. Stresemann (1939b:324) presents a map of the distribution ofA. arundinaceousin southeastern Asia and adjacent islands. The original stock came from a point in China, north of Indochina, spreading to the Philippines and to Celebes, from where it reached the Solomons and New Guinea via the Lesser Sundas and Australia.

Fig. 15Fig. 15.Geographic distribution ofAcrocephalusin the Pacific area and routes of its dispersal. (1)A. arundinaceus; (2)A. luscinia; (3) ranges ofA. atypha,A. caffra, andA. vaughani; (4)A. aequinoctialis; (5)A. familiaris.

The path of invasion of Oceania by the reed-warbler is pictured infigure 15. Probably the birds became established in Micronesia by an invasion from the Bonins, whereA. arundinaceus orientalisis known to occur today. From the Marianas and Carolines, the birds spread to Polynesia;A. l. rehseiof the Gilbert Islands (Nauru) might well be a connecting link. Possibly, the Hawaiian birds came as a separate invasionviathe Volcano and Bonin islands or through the Micronesia Chain, or through the Line and Christmas islands from the south. It seems evident, however, that owing to their geographic proximity and comparative structural similarity, the species in Hawaii is closest toA. lusciniaof Micronesia. The absence of reed-warblers from the western Carolines and Palaus seems to reduce the possibility of an invasion from the Philippine region. However, reed-warblers are absent from the Marshall and the northern Gilbert islands, where there is undoubtedly suitable habitat for their occurrence. Possibly these islands were once occupied by the birds but they were eliminated by natural causes or by man and his land uses.

Rhipidura UraniaeOustalet, Bull. Soc. Philom. Paris, (7), 5, 1881, p. 76. (Type locality, Mariannes = Guam.)

Rhipidura pectoralisGray, Cat. Birds Trop. Is. Pacific Ocean, 1859, p. 17 (Ladrone or Marian Is. = Guam).

Rhipidura uraniaeReichenow and Schlow, Journ. f. Ornith., 1884, p. 398 (Mariannes = Guam); Hartert, Novit. Zool., 5, 1898, p. 53 (Guam); Wiglesworth, Abhandl. und Ber. Zool. Mus. Dresden, no. 6, 1890-1891 (1891), p. 20 (Marianne = Guam); Büttikofer, Notes Leyden Mus., 15, 1893, p. 76 (Guam); Wheeler, Report Island of Guam, 1900, p. 13 (Guam); Matschie, Journ. f. Ornith., 1901, pp. 112, 113 (Guam); Seale, Occ. Papers Bernice P. Bishop Mus., 1, 1901, p. 48 (Guam); Safford, Osprey, 1902, p. 69 (Guam); Dubois, Syn. Avium, 1, 1902, p. 277 (Guam); Safford, The Plant World, 7, 1904, p. 263 (Guam);idem, Contr. U. S. Nat. Herb., 9, 1905, p. 79 (Guam); Mearns, Proc. U. S. Nat. Mus., 36, 1909, p. 477 (Guam); Schnee, Zeitschr. f. Naturwisch., 82, 1910, p. 464 (Marianen = Guam); Reichenow, Die Vögel, 2, 1914, p. 267 (Marianen = Guam); Cox, Island of Guam, 1917, p. 21 (Guam); Kuroda, in Momiyama, Birds Micronesia, 1922, p. 65 (Guam); Bryan, Guam Rec., vol. 13, no. 2, 1936, p. 25 (Guam).

Rhipidura atrigularisReichenow, Journ. f. Ornith., 1885, p. 110 (Type locality, Palau, error = Guam); Wiglesworth, Abhandl. und Ber. Zool. Mus. Dresden, no. 6, 1890-1891 (1891), p. 21 (Pelew, error = Guam); Takatsukasa and Kuroda, Tori, 1, 1915, p. 63 (Marianne = Guam).

Rhipidura versicolorOustalet (part), Nouv. Arch. Mus. Hist. Nat. Paris, (3), 7, 1895, p. 190 (Guam).

Rhipidura rufifrons uraniaeMathews, Syst. Avium Australasianarum, 2, 1930, p. 490 (Marianne = Guam); Hand-list Japanese Birds, rev., 1932, p. 176 (Guam); Hand-list Japanese Birds, 3d ed., 1942, p. 195 (Guam); Mayr, Birds Southwest Pacific, 1945, p. 295 (Guam); Watson, The Raven, 17, 1946, p. 42 (Guam); Mayr and Moynihan, Amer. Mus. Novit., no. 1321, 1946, pp. 3, 9 (Guam); Baker, Proc. Biol. Soc. Washington, 59, 1946, p. 77 (Guam);idem, Smithson. Misc. Coll., vol. 107, no. 15, 1948, p. 67 (Guam).

Rhipidura rufifronsWharton, Ecol. Monogr., 16, 1948, p. 174 (Guam); Strophlet, Auk, 1946, p. 339 (Guam).

Geographic range.—Micronesia: Mariana Islands—Guam.

Characters.—Adult: Forehead and anterior crown near "cinnamon-buff"; lores and orbital ring black, auriculars more brownish than lores; malar stripe white; a few feathers in posterior malar region tipped with "citrine drab"; anterior part of chin white; posterior part of chin, throat, and upper breast black; feathers on breast edged with white; lower breast, abdomen, sides, flanks, tibia, vent, and under tail-coverts near "royal brown," becoming lighter on breast and more rufous on under tail-coverts; sides of neck and back near "Dresden brown," becoming grayer on neck and crown where feathers have darker shafts; rump and upper tail-coverts near "orange rufous"; basal half of tail slightly lighter than rump; terminal part of tail black, tipped with white; wings dark edged with coloring like back; under wing grayish with axillaries tipped with buffy-white; bill black with base of upper mandible lighter; feet dark brown; iris dark brown.

Immature: Resembles adult, but head, neck, scapulars, and secondaries edged with rufous; feathers of chin and throat edged with whitish. Younger birds may have less rufous on head but feathers of body more rufous with creamy edges.

Measurements.—Measurements are listed intable 38.

Table 38. Measurements ofRhipidura rufifronsin Micronesia

11 males

6 females

7 males

6 females

2 males

14 males

10 females

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