Nycticorax caledonicus pelewensisMathews

Ardes NycticoraxLinnaeus, Syst. Nat., ed. 10, 1, 1758, p. 142. (Type locality, Southern Europe.)

Nycticorax griseusHartlaub and Finsch, Proc. Zool. Soc. London, 1872, pp. 89, 105 (Uap); Gräffe, Journ. Mus. Godeffroy, 2, 1873, p. 123 (Yap); Wiglesworth, Abhandl. und Ber. Zool. Mus. Dresden, no. 6, 1890-1891 (1891), p. 69 (Uap).

Nycticorax nycticoraxSharpe, Cat. Birds British Mus., 26, 1898, p. 146 (Yap).

Nycticorax nycticorax nycticoraxKuroda, in Momiyama, Birds Micronesia, 1922, p. 36 (Mackenzie, Yap); Hand-list Japanese Birds, rev., 1932, p. 183 (Yap, Uluthi); Hand-list Japanese Birds, 3d ed., 1942, p. 204 (Yap, Uluthi); Mayr, Birds Southwest Pacific, 1945, p. 302 (Marianas, Yap).

Geographic range.—Europe and Africa east to Japan and Malaysia. In Micronesia: Mariana Islands—Tinian; Palau Islands—Koror; Caroline Islands—Yap, Ulithi, Truk.

Specimens examined.—Total number, 2 immature females, as follows: Palau Islands, USNM—Koror, 1 (Nov. 27); Caroline Islands, AMNH—Truk, 1 (June 18).

Remarks.—The Black-crowned Night Heron is a winter visitor to western Micronesia. Marshall (1949:221) records six of these birds on Tinian on April 4, 1945, and one on Koror on November 27.

Nycticorax caledonicus pelewensisMathews, Bull. British Ornith. Club, 46, 1926, p. 60. (Type locality, Pelew Islands.)

Nycticorax caledonicusHartlaub and Finsch, Proc. Zool. Soc. London, 1868, pp. 117, 118 (Pelew); Sharpe, Cat. Birds British Mus., 26, 1898, p. 158 (Pelew); Hartert, Novit. Zool., 7, 1900, p. 10 (Ruk); Reichenow, Die Vögel, 1, 1913, p. 255 (Palauinseln); Takatsukasa and Kuroda, Tori, 1, 1915, p. 50 (Pelew); Uchida, Annot. Zool. Japon., 9, 1918, p. 486 (Palau); Wetmore, in Towsend and Wetmore, Bull. Mus. Comp. Zoöl., 63, 1919, p. 172 (Uala, Truk Atoll); Kuroda, in Momiyama, Birds Micronesia, 1922, p. 37 (Pelew, Ruk).

Nycticorax manillensisHartlaub and Finsch, Proc. Zool. Soc. London, 1872, pp. 89, 105 (Pelew); Finsch, Journ. Mus. Godeffroy, 8, 1875, pp. 5, 33 (Palau);idem, Proc. Zool. Soc. London, 1880, p. 577 (Ruk); Schmeltz and Krause, Ethnogr. Abth. Mus. Godeffroy, 1881, p. 353 (Ruk); Wiglesworth, Abhandl. und Ber. Zool. Mus. Dresden, no. 6, 1890-1891 (1891), p. 69 (Pelew, Ruk).

Nycticorax caledonicus pelewensisMathews, Syst. Avium Australasianarum, 1, 1927, p. 200 (Pelew, Carolines); Peters, Proc. Boston Soc. Nat. Hist., 39, 1930, p. 271 (Pelew, Carolines); Peters, Check-list Birds World, 1, 1931, p. 115 (Pelew); Hand-list Japanese Birds, rev., 1932, p. 183 (Palau, Truk); Hand-list Japanese Birds, 3d ed., 1942, p. 204 (Babelthuap, Koror, Coracel, Truk); Amadon, Amer. Mus. Novit., no. 1175, 1942, p. 6 (Palau, Ruk); Mayr, Birds Southwest Pacific, 1945, p. 285 (Palau, Truk); Baker, Smithson. Misc. Coll., vol. 107, no. 15, 1948, p. 43 (Angaur, Peleliu, Garakayo, Truk).

Geographic range.—Micronesia: Palau Islands—Babelthuap, Koror, Coracel, Garakayo, Peleliu, Ngabad, Angaur; Caroline Islands—Truk.

Characters.—Adult: Size medium; head and nape dark slaty-black; occipital plumes white with dark tips and shafts; back dark reddish-brown, lighter on sides of neck, wings, wing coverts, rump, and tail; under parts whitish with light reddish-brown on sides of neck extending to throat and upper breast; tibia with some brownish feathers; underwing pinkish; feet yellowish-brown; bill black.

Immature: Resembles adult, but upper parts mottled black with reddish-brown; underparts with lighter streaks of brown and whitish on breast; feet yellowish; bill black above, yellowish below.

Adult resemblesN. c. manillensisVigors, but is duller above.

Measurements.—Two adult males from Peleliu measure: wing, 293, 299; tail, 105, 107; culmen, 82, 89; tarsus, 79, 81; seven adult females from Peleliu: wing, 269-286 (280); tail, 101-106 (104); culmen, 76-84 (80); tarsus, 78-83 (80); one adult female from Truk: wing, 280; tail, 97; culmen, 83; tarsus, 79.

Specimens examined.—Total number, 27 (5 males, 18 females, 4 unsexed), as follows: Palau Islands, USNM—Peleliu, 9 (Aug. 31, Sept. 1, 5, 6, 8, Dec. 6); AMNH—exact locality not given, 16 (Nov. 7, 8, 13, 23, 25, Dec. 1, undated); Caroline Islands, USNM—Truk, 1 (Feb. 16); AMNH—Truk, 1 (May 25).

Nesting.—The NAMRU2 party observed a nesting colony of these night herons at Peleliu on August 29, 1945. Approximately eight nests were observed in a grove of saplinglike trees at the edge of a mangrove swamp. These nests were 15 to 20 feet above the ground; most of them contained one or two nestling birds. Two subadults and three nestlings in postnatal molt were obtained; no eggs were found. Marshall (1948:219) records breeding in August, September and December.

Food habits.—Baker (1948:43) reports that stomachs of night herons obtained by the NAMRU2 party at Peleliu contained a great variety of animal foods, including eels, fish, lizards (skinks), crabs, shrimp, and insects. The stomach of one adult contained 14 large grasshoppers and four fish, totaling about 15 cc. in volume. The nestlings had eels, skinks, and insects in their stomachs.

Parasites.—Uchida (1918:486) found the bird louse (Mallophaga),Lipeurus baculus, on the night heron at Palau.

Remarks.—Amadon (1942:4-8) has made the most recent study of the speciesNycticorax caledonicusand recognizes eight subspecies from Australia and New Calendonia north to the Caroline and Bonin islands. This is one of the few tropical and subtropical species which has extended its range to the Bonin islands. The discontinuous distributions of this species prevents an accurate estimation of the route by which it reached the Bonins. The presence of the bird at Palau and at Truk makes it difficult to account for its absence at Yap and other intervening, and seemingly suitable, islands. Populations at Palau and Truk appear to be similar and are placed in the same subspecies, but when adequate material is available from Truk, further study may reveal that the populations on the two islands (Truk and Palau) are recognizably different.

At the southern Palau Islands, night herons were found by the NAMRU2 party in mangrove swamps, lagoons and on beaches. I found them to be inactive during the daytime; the birds were usually perched singly in trees or at the edge of the water. The birds appeared to have special roosting places and were observed sitting in the same place on several different occasions. McElroy of the NAMRU2 party reported seeing three night herons at Truk in December, 1945.

Nycticorax goisagiTemminck, Pl. Col., livr. 98, 1835, pl. 582. (Type locality, Japan.)

Gorsakius goisagiHand-list Japanese Birds, rev., 1932, p. 184 (Koror); Hand-list Japanese Birds, 3d ed., 1942, p. 204 (Koror); Mayr, Birds Southwest Pacific, 1945, p. 302 (Palau).

Geographic range.—Eastern China, Japan, Riu Kius, Formosa, and Philippine Islands. In Micronesia: Palau Islands—Koror.

Remarks.—Gorsachius goisagihas been recorded from Koror in the Palau Islands. It may be classed as a rare migrant to western Micronesia.

Ardea melanolophaRaffles, Trans. Linn. Soc. London, 13, 1822, p. 326. (Type locality, Western Sumatra.)

Nycticorax goisagiHartlaub and Finsch, Proc. Zool. London, 1868, pp. 8, 118 (Pelew);idem, Proc. Zool. Soc. London, 1872, p. 89 (Pelew); Wiglesworth, Abhandl. und Ber. Zool. Mus. Dresden, no. 6, 1890-1891 (1891), p. 68 (Pelew).

Nycticorax melanolophusFinsch, Journ. Mus. Godeffroy, 8, 1875, pp. 5, 35 (Palau).

Gorsachius melanolophusSharpe, Cat. Birds Brit. Mus., 26, 1898, p. 166 (Pelew).

Gorsahius melanolophus melanolophusHand-list Japanese Birds, rev., 1932, p. 184 (Pelew); Hand-list Japanese Birds, 3d ed., 1942, p. 204 (Palau); Mayr, Birds Southwest Pacific, 1945, p. 302 (Palau).

Gorsachius melanolophus melanolophusMathews, Syst. Avium Australasianarum, 1, 1927, p. 200 (Pelew).

Geographic range.—India, Ceylon, southern China, Formosa, Indochina, Malaysia. In Micronesia: Palau Islands—exact locality unknown.

Remarks.—Captain Tetens obtained a specimen of this bittern at the Palau Islands which was reported on by Hartlaub and Finsch (1868a:8, 1868b:118). It is probably a rare straggler to western Micronesia. The specimen has not been seen by me; it may be of the subspeciesG. m. kutteri(Cabanis), which is known from the Philippine Islands.

Ardea SinensisGmelin, Syst. Nat., 1, pt. 2, 1789, p. 642. (Type locality, China.)

Ardea lepidaLesson, Traité d'Ornith., 1831, p. 573 (Marianne); Hartlaub, Journ. f. Ornith., 1854, p. 167 (Mariannen).

Ardea sinensisKittlitz, Obser. Zool., in Lutké, Voy. "Le Séniavine," 3, 1836, p. 305 (Guahan); Gray, Hand-list Birds, 3, 1871, p. 31 (Marian); Hartlaub and Finsch, Proc. Zool. Soc. London, 1872, pp. 89, 105 (Uap); Gräffe, Journ. Mus. Godeffroy, 2, 1873, p. 123 (Yap); Finsch, Journ. Mus. Godeffroy, 8, 1875, pp. 5, 33 (Palau, Yap);idem, Proc. Zool. Soc. London, 1880, p. 577 (Ruk); Schmeltz and Krause, Ethnogr. Abth. Mus. Godeffroy, 1881, p. 353 (Ruk).

Ardea (Ardetta) sinensisGray, Cat. Birds Trop. Is. Pacific Ocean, 1859, p. 49 (Ladrone or Marian Islands).

Ardetta SinensisSalvadori, Ornith. Papuasia, 3, 1882, p. 364 (Pelew, Carolines, Mariannis); Oustalet, Le Nat., 1889, p. 261 (Mariannes); Wiglesworth, Abhandl. und Ber. Zool. Mus. Dresden, no. 6, 1890-1891 (1891), p. 68 (Marianne, Uap, Ruk, Pelew); Oustalet, Nouv. Arch, Mus. Hist. Nat. Paris, (3), 8, 1896, pp. 38, 39 (Guam, Saypan, Ponapi, Ruk, Palaos); Hartert, Novit. Zool., 5, 1898, p. 65 (Guam); Sharpe, Cat. Birds British Mus., 26, 1898, p. 227 (Marianne, Carolines, Pelew); Hartert, Novit. Zool., 7, 1900, p. 11 (Ruk); Safford, Contr. U. S. Nat. Herb., 9, 1905, p. 79 (Guam); Prowazek, Die deutschen Marianan, 1913, p. 100 (Saipan); Cox, Island of Guam, 1917, p. 21 (Guam).

Ardetta bryaniSeale, Occ. Papers Bernice P. Bishop Mus., 1, 1901, p. 27 (Type locality, Guam); Safford, Osprey, 1902, p. 66 (Guam);idem, The Plant World, p. 266 (Guam).

Ardetta sinensis sinensisTakatsukasa and Kuroda, Tori, 1, 1915, p. 50 (Ruk, Pelew).

Ixobrychus sinensis bryaniWetmore, in Townsend and Wetmore, Bull. Mus. Comp. Zoöl., 63, 1919, pp. 173, 175 (Guam); Kuroda, in Momoyama, Birds Micronesia, 1922, p. 37 (Guam,?Yap,?Mackenzie,?Pelew);idem, Avifauna Riu Kiu, 1925, p. 134 (Guam,?Yap,?Pelew); Mathews, Syst. Avium Australasianarum, 1, 1927, p. 202 (Guam,?Pelew); Peters, Check-list Birds World, 1, 1931, p. 121 (Guam); Hand-list Japanese Birds, rev., 1932, p. 184 (Saipan, Tinian, Rota, Guam); Oberholser, Bull. U. S. Nat. Mus., 159, 1932, p. 18 (Guam); Bryan, Guam Rec., vol. 13, no. 2, 1936, p. 15 (Guam); Hand-list Japanese Birds, 3d ed., 1942, p. 205 (Saipan, Tinian, Rota, Guam); Amadon, Bull. Bernice P. Bishop Mus., 186, 1945, p. 25 (Guam); Stott, Auk, 64, 1947, p. 525 (Saipan); Baker, Smithson. Misc. Coll., vol. 107, no. 15, 1948, p. 44 (Rota, Guam).

Ixobrychus sinensis mooreiWetmore, in Townsend and Wetmore, Bull. Mus. Comp. Zoöl., 63, 1919, p. 173 (Type locality, Uala, Truk group); Kuroda, in Momiyama, Birds Micronesia, 1922, p. 38 (Ruk); Kuroda, Avifauna Riu Kiu, 1925, p. 134 (Ruk); Mathews, Syst. Avium Australasianarum, 1, 1927, p. 202 (Middle Carolines); Peters, Check-list Birds World, 1, 1931, p. 121 (Truk); Hand-list Japanese Birds, rev., 1932, p. 184 (Palaus, Yap, Truk); Oberholser, Bull. U. S. Nat. Mus., 159, 1932, p. 17 (Carolines, ?Pelews); Hand-list Japanese Birds, 3d ed., 1942, p. 205 (Babelthuap, Koror, Yap, Truk); Baker, Smithson. Misc. Coll., vol. 107, no. 15, 1948, p. 44 (Truk, Peleliu).

Ixobrychus sinensisHartert, Vogel pal. Fauna, 10, 1920, p. 1260 (Truk, Palau, Guam); Mayr, Birds Southwest Pacific, 1945, p. 285 (Marianas, Palau, Yap, Truk); Watson, The Raven, 17, 1946, p. 41 (Guam); Downs, Trans. Kansas Acad. Sci., 49, 1946, p. 91 (Tinian); Wharton, Ecol. Monogr., 16, 1946, p. 174 (Guam); Delacour and Mayr, Birds Philippines, 1946, p. 29 (Guam); Strophlet, Auk, 63, 1946, p. 536, (Guam); Baker, Condor, 49, 1947, p. 125 (Guam).

Ixobrychus sinensis sinensisHachisuka, Birds Philippines, 1, 1932, p. 365 (Guam, Truk); Robinson and Chasen, Birds Malay Peninsula, 3, 1936, p. 195 (Marianne).

Ixobrychus sinensis palewensisMomiyama, Bull. Biogeogr. Soc. Japan, 2, 1932, p. 333 (Type locality, Pelew); Mathews, Ibis, 1933, p. 88 (Pelew).

Ixobrychus sinensis yapensisMomiyama, Bull. Biogeogr. Soc. Japan, 2, 1932, p. 333 (Type locality, Yap); Mathews, Ibis, 1933, p. 89 (Yap).

Geographic range.—Northeastern China and Japan south to Micronesia, Malaysia, Burma, India and Ceylon. Winter visitor to Papuan region. In Micronesia: Mariana Islands—Saipan, Tinian, Rota, Guam; Palau Islands—Babelthuap, Koror, Peleliu; Caroline Islands—Yap, Truk.

Characters.—Adult male: A small bittern with crown and short occipital crest slaty-black; mantle light buffy-brown; back and rump gray; tail black; wing-coverts brownish-buff; primaries and secondaries slaty-black; underparts yellowish buff; chin and throat whitish; sides of head and neck and a line of feathers across chest blackish edged with buff; bill yellowish green; feet greenish yellow.

Adult female: Resembles adult male, but with upper parts mottled brown and golden chestnut; underparts deep buff streaked with pale brown on neck.

Immature: Resembles adult, with upper parts heavily streaked with blackish-brown, and underparts streaked with chestnut and dark brown.

Measurements.—Measurements of specimens from Micronesia are given intable 16.

Table 16. Measurements ofIxobrychus sinensisFrom Micronesia

Weights.—The author (1948: 44) records the weights of eight adult males from Guam as 82-103 (92) and eight adult females from Guam as 84-109 (95).

Specimens examined.—Total number, 69 (34 males, 27 females, 8 unsexed), as follows: Mariana Islands, USNM—Saipan, 1 (Sept. 30)—Tinian, 1 (Oct. 13)—Guam, 29 (May 16, June 4, 6, 7, 8, 14, 18, 19, July 10, 16, 18, 24, 27, Aug. 4); AMNH—Saipan, 1 (Aug. 6)—Tinian, 3 (Sept. 13)—Guam, 14 (Feb. 1, Mar. 13, 29, July 11, 13, 25, Aug. 1, 7, 13, Sept. 4, 10, Dec. 8); Palau Islands, AMNH—exact locality not given, 6 (Nov. 19, 21, 23, 25, Dec. 1, 18); Caroline Islands, USNM—Truk, 1 (Feb. 16); AMNH—Yap, 1 (not dated)—Truk, 12 (Feb. 9, Mar. 5, 17, May 7, June 13, 14, 15, Oct. 3, Nov. 1, 5, Dec. 20).

Nesting.—The author (1948:44) records a nest found by the NAMRU2 party near Achang Bay on Guam on June 6, 1945. It was found in a cane thicket at the edge of a fallow rice paddy, approximately four feet from the ground and was constructed of about three quarts of reeds and cane. Two eggs found in the nest are oval, white with a greenish cast and measure 33 by 24 and 34 by 24. On February 1, 1945, the writer found two recently occupied nests of the Chinese Least Bittern at Oca Point, Guam. These nests were in dense inkberry brush approximately five feet above the ground. The area was not marshy, the nearest water being at the beach some 300 yards away. Nearby one of the nests was found a young bittern, which apparently had only recently left the nest. The pin feathers were growing. A parent bird remained in the vicinity with the young bird until it left the area after March 9.

Food habits.—The Chinese Least Bittern feeds on animal foods obtained along waterways, marshes and beaches as well as in forests and fields. The NAMRU2 party observed several types of insects in the stomachs of birds taken at Guam. Seale (1901:27) found black crickets in stomachs of bitterns taken at Guam. Coultas (field notes) learned from the natives of the Palau Islands that the bittern feeds on land mollusks.

Parasites.—Wharton (1946:174) obtained the chigger (Acarina),Trombicula acuscutellaris, from the Chinese Least Bittern at Guam.

Remarks.—The Chinese Least Bittern has been regarded by many workers as consisting of several geographic races; as many as eight have been recognized. Other workers have concluded thatI. sinensisis made up of highly variable populations and that it lacks well-fined geographic variation. Hartert (1920:1260), Hachisuka (1932:365), and Mayr (1945a:285) have reached the latter conclusion. As yet this problem has not been satisfactorily solved; a thorough study is needed, but may not be possible until additional material, especially from the continental areas, can be obtained. In coloration there appears to be little difference between birds from the various localities in Micronesia. These birds may average slightly paler than populations from the continental areas, but on this basis I doubt that a person could recognize the Micronesian birds in a group of skins from many other localities. Birds in fresh plumage may show geographic differences better than slightly worn specimens. Measurements made by the author offer no clear-cut differences either.

I. sinensiswas first recorded in Micronesia by Quoy and Gaimard (1824:536), whose ship, the "Uranie," stopped at Guam. They called the bird "Petit Héron aux ailes noires." Most of the ornithological collectors in the years following Quoy and Gaimard obtained this bittern in Micronesia. At Guam, its abundance and the ease with which it may be approached and shot is attested by the large series obtained by collectors: Seale (1901:27) took eight birds;Marche (Oustalet, 1896:36) took eighteen skins; the NAMRU2 party took twenty-nine skins.

The Chinese Least Bittern is found in habitats associated with both salt water and fresh water, as well as in upland habitat in Micronesia. The bird appears to be well adapted to areas of open forest and coconut groves. Coultas (field notes) found the birds in taro patches in the Palaus. Although a considerable amount of field observing was done in the southern Palaus, the NAMRU2 party saw only one bird (September 13, 1945, at Peleliu). Perhaps the birds prefer Babelthuap and other large islands farther north in the chain. McElroy found bitterns in taro patches at Truk in December, 1945. The NAMRU2 party did not find any birds at Rota in October and November, 1945. Downs (1946:91) found the birds in upland sugar cane and beach habitats on Tinian.

Regarding the bittern in the Palaus, Coultas (field notes) writes, "Always found alone, never a pair. A bird that is not easily frightened. In the heat of the day, one finds it standing in the shade of a taro leaf quietly viewing the intruder and very reluctant about moving. I have tossed pieces of earth and sticks at the bird to encourage him to fly so that I would not blow him to pieces when I shot, but my efforts at dislodgement have been rewarded by harsh scolding squawks. It became necessary for me to move into proper gun range. I have also found them perched in low trees at the edge of taro swamps. In flight they are atrociously awkward. They can't keep a course and their legs dangle every-which way. Their jerky, slow flight usually ends abruptly when the bird becomes entangled in weeds or the branches of trees. Extracting himself from his predicament he is soon in another and invariably resorts to blasphemy."

Ardetta eurhythmaSwinhoe, Ibis, 1873, p. 74, pl. 2. (Type locality, Amoy Shanghai.)

Ixobrychus eurythmusMayr, Birds Southwest Pacific, 1945, p. 302 (Palau).

Geographic range.—Southeastern Siberia and Japan south to India and Malaysia. In Micronesia: Palau Islands—exact locality unknown.

Specimens examined.—Total number, 3 (2 males, 1 female), from Palau Islands, AMNH—exact locality not given (Nov. 19, 21, Dec. 3).

Remarks.—Coultas obtained three immature specimens at Palau in November and December, 1931.

Ardea flavicollisLatham, Ind. Ornith., 2, 1790, p. 701. (Type locality, India.)

Dupetor flavicollisSeale, Occ. Papers Bernice P. Bishop Mus., 1, 1901, p. 26 (Guam); Bryan, Guam Rec., vol. 13, no. 2, 1936, p. 15 (Guam).

Dupetor f. flavicollisMayr, Birds Southwest Pacific, 1945, p. 302 (Guam).

Geographic range.—Central China south to Malaysia and India. In Micronesia: Mariana Islands—Guam.

Remarks.—Seale (1901:26) records a female shot at the Agaña River on Guam on June 11, 1900. The skin probably is in the Bernice P. Bishop Museum in Honolulu.

Anas oustaletiSalvadori, Bull. British Ornith. Club, 4, 1894, p. 1. (Type locality, Mariannis Islands.)

Anas oustaletiSalvadori, Cat. Birds British Mus., 27, 1895, p. 189 (Guaham); Oustalet, Nouv. Arch. Mus. Hist. Nat. Paris, (3), 8, 1896, p. 49 (Guam); Hartert, Novit. Zool., 5, 1898, p. 66 (Guam, Saipan); Wheeler, Report Island of Guam, 1900, p. 13 (Guam); Seale, Occ. Papers Bernice P. Bishop Mus., 1, 1901, p. 25 (Guam, Saipan); Matschie, Journ. f. Ornith., 1901, pp. 110, 113 (Guam, Saipan); Safford, Osprey, 1902, p. 66 (Mariannas);idem, Amer. Anthro., 4, 1902, p. 711 (Guam);idem, The Plant World, 7, 1904, p. 267 (Guam); Dubois, Syn. Avium, 2, 1904, p. 990 (Mariannes); Safford, Contr. U. S. Nat. Herb., 9, 1905, pp. 80, 126 (Guam); Prowazek, Die deutschen Marianen, 1913, pp. 47, 100 (Marianen); Cox, Island of Guam, 1917, p. 22 (Guam); Phillips, Nat. Hist. Ducks, 2, 1923, p. 53 (Guam, Saipan); Mathews, Syst. Avium Australasianarum, 1, 1927, p. 214 (Guam, Saipan); Berlioz, Bull. Mus. Hist. Nat. Paris, 2d ser., 1, 1929, p. 67 (Guam); Peters, Check-list Birds World, 1, 1931, p. 159 (Guam, Tinian, Saipan); Hand-list Japanese Birds, rev., 1932, p. 184 (Guam, Tinian, Saipan); Bryan, Guam Rec., vol. 13, no. 2, 1936, p. 15 (Guam); Kuroda, Tori, 11, 1941-42, pp. 99, 443 (Marianas); Hand-list Japanese Birds, 3d ed., 1942, p. 205 (Guam, Tinian, Saipan); Amadon, Amer. Mus. Novit., no. 1237, 1943, p. 1 (Marianne); Mayr, Birds Southwest Pacific, 1945, p. 285 (Marianas);idem, Audubon Mag., 47, 1945, p. 282 (Marianas); Baker, Trans. 11th N. Amer. Wildlife Conf., 1946, p. 208 (Guam); Stott, Auk. 64, 1947, p. 525 (Saipan); Baker, Smithson, Misc. Coll., vol. 107, no. 15, 1948, p. 45 (Saipan, Tinian); Momiyama, Pacific Science, 2, 1948, p. 121 (Saipan, Tinian, Guam).

Polionetta oustaletiKuroda, in Momiyama, Birds Micronesia, 1922, p. 39 (Guam, Saipan).

Anas superciliosa oustaletiHartert, Novit. Zool., 36, 1930, p. 112 (Guam, Saipan).

Anas platyrhynchos oustaletiDelacour and Mayr, Wilson Bull., 57, 1945, pp. 21, 39 (Marianas).

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

Characters.—From study of a large series of specimens ofAnas oustaleti, Yamashina (1948) described two types of plumages: one type resembles that ofA. platyrhynchosand another type resembles that ofA. poecilorhyncha. He based his conclusions on both a study of prepared skins and observations of the molt of living specimens as reported by Kuroda (1941-1942). The following descriptions are quoted from Yamashina (1948:122).

Adult male in nuptial plumage ofA. platyrhynchostype: "Whole head is dark green, except at the sides where buff feathers are plentifully intermingled, a dark brown streak through the eye, and faint white ring on the lower neck. Feathers on scapulars and sides of body are as those ofAnas poecilorhyncha. Sides of body are vermiculated but some brown feathers are found even in the full nuptial plumage. Upper breast is dark reddish chestnut with dusky spots. Upper and under tail-coverts are as inAnas platyrhynchos. Speculum is as that ofAnas platyrhynchos, but the tips of the greater coverts are buff instead of white. Central tail feathers are more or less curled upward. Base of bill is black, tip is olive color. Iris is dark brown. Feet, reddish-orange, webs darker." Eclipse plumage of adult male resembles that ofA. platyrhynchos.

Adult male in nuptial plumage ofA. poecilorhynchatype: "ResemblesAnas poecilorhyncha pelewensisfrom the Palau Islands and Truk Island, but sides of head are browner, superciliary stripes and ground color of cheeks are more buffy. Feathers on upper breast and sides of body are more broadly edged with brown. Speculum is usually violet-purple as in theplatyrhynchostype, but in two specimens from Saipan and Tinian, respectively, it is dark green as inAnas poecilorhyncha pelewensis. Tips of the secondaries are usually white, but sometimes very faint as inAnas poecilorhyncha pelewensis, and in one specimen from Saipan they are buffy. Bill is olive color with a black spot in the center of the upper mandible. Iris, dark brown. Feet, dark orange, darker in joints and webs." Eclipse plumage of adult male resembles the nuptial plumage.

Measurements.—Measurements of nine ducks from Guam and Saipan are: wing, 238-266 (252); tail, 75-84 (81); exposed culmen, 49-53 (51); tarsus, 41-43 (42).

Specimens examined.—Total number, 9 (5 males, 2 females, 2 unsexed), as follows: Mariana Islands, USNM—Saipan, 2 (Oct. 2, 3)—Guam, 1 (June 6); AMNH—Saipan, 2 (Aug. 7, 11)—Guam, 4 (Jan. 10, April 6, Dec. 11, 16).

Nesting.—At Guam, Seale (1901:25) found nests of the Marianas Mallard "among the reedy swamps and streams of the island." He obtained two downy young in June. Kuroda (1941-1942) reports nesting at Lake Challankanoa, Saipan, in July. He writes that nests contained 7 to 12 eggs. Ducklings and incubated eggs were obtained in June and July, but he is of the opinion that the breeding season may be longer. He notes that adults exhibit both nuptial plumage and eclipse plumage at the same time, suggesting that breeding may occur at various times in the year. A nest with seven eggs taken on July 4, 1941, at Hagoi Lake, Tinian, is described by Kuroda as having been found among rushes and constructed of dead leaves, stems, and roots and lined with down. He describes the eggs as being grayish-white with a pale greenish tinge, and measuring 61.6 by 38.9. Marshall (1949:202) saw a family of ducklings in April.

Remarks.—The Marianas Mallard is rare; probably it never has been very abundant in the small chain of islands to which it is restricted, because fresh water marshes and swamps are not extensive. The bird was first recorded by Bonaparte asAnas boschas a. Freycinetiin 1865. This name was anomen nudumand later the same specimen in the Paris Museum was named by Salvadori (1894) asAnas oustaleti. In 1888, Marche obtained six specimens at Guam; these were reported on by Oustalet (1896:49). Later collectingshowed that the duck inhabited also the islands of Saipan and Tinian. There have been no records of this duck in the more northern islands of the Marianas. According to Yamashina (1948:121) in the period from 1931 to 1940, the Japanese obtained 38 specimens of the Marianas Mallard at Tinian and Saipan. In 1940, four birds from Tinian were shipped alive to Japan and kept in an aviary by Kuroda. At Tinian in 1940, one of the collectors observed two flocks ofA. oustaleti, each containing 50 or 60 individuals. The Japanese took specimens at a lagoon area and at fresh water lakes. Yamashina describes one of the localities, Lake Hagoi on Tinian, as "a small body of fresh water surrounded by about 40 acres of marsh." During the war, servicemen reported the presence of the Marianas Mallard at both Saipan and Tinian. Moran (1946:261) counted twelve ducks at Saipan. Stott (1947:525) saw seven birds at Lake Susupe on Saipan in December, 1945. He writes that the birds were gentle and easily approached and that they preferred winding channels in reed beds to open water. Marshall obtained two ducks at Lake Susupe in early October, 1945. These specimens are in the United States National Museum. He (1949:202) found ducks at both Saipan and Tinian; twelve was the greatest number seen at any one time. Gleise (1945:220) estimated that there were twelve birds on Tinian in 1945, remarking that their habitat was swamp area.

At Guam and Rota, the NAMRU2 party failed to obtain any specimens but received reports of the presence of ducks on both islands. At Guam, reports were obtained of ducks of unknown species at a fallow rice paddy in August, 1944, and in a marsh near Agat on June 13, 1945. The presence of Japanese soldiers in the interior of Guam made it inadvisable to investigate marshes and swamps of the interior and the upper courses of streams. H. G. Hornbostel, as quoted by Phillips (1923:54), reported that ducks were found at Guam only in the Tolofofo River Valley. The NAMRU2 field parties investigated the lower reaches of this valley and found no evidence of the ducks. The upper part of this valley was used as an artillery range in 1945. Probably the firing of field guns was a disturbing influence to any birds that might have been there. If the ducks were on Guam at that time, they must have been secretive and restricted in their movements. At Rota, two ducks which might have beenA. oustaletiwere seen by the NAMRU2 party on October 20, 1945, in a cultivated field.

These recent reports indicate that the Marianas Mallard is secure for the present on the islands of Saipan and Tinian, but thoughtfulconservation practices need to be placed in operation to insure its survival in the future.

Evolutionary history of Anas oustaleti.—In the past, most of the studies have pointed to a northern ancestry forA. oustaleti. Bryan (1941:187) has noted a relationship betweenA. oustaletiand the Laysan Duck (A. laysanensisRothschild) and the Hawaiian Duck (A. wyvillianaSclater). Amadon (1943:1) suggests that these three species of ducks are rather recent derivatives of the Common Mallard (A. platyrhynchos) and postulates the evolution ofA. wyvillianafrom migrants from North America. He further states thatA. laysanensisandA. oustaletimay have been derived fromA. wyvillianaor may represent independent colonizations. Delacour and Mayr (1945:21) go a step further and make these forms subspecies ofA. platyrhynchos, saying that they are "dull-colored editions" of the Common Mallard, that because of isolation they have become reduced in size and have lost many of the characteristics of their ancestors. Recently, however, Yamashina (1948) has concluded that the Marianas Mallard has evolved as the result of hybridization between the two species,A. platyrhynchosandA. poecilorhyncha. His conclusions are based on a study of a large number of specimens, both museum skins and captive birds, in which he has been able to detect plumages of theA. platyrhynchostype and of theA. poecilorhynchatype (see Characters). He has noted specimens which have ninety percent of the characteristics ofA. platyrhynchosand ten percent of theA. poecilorhynchatype. These percentages are reversed in specimens favoring theA. poecilorhynchatype. In his series of skins he finds theA. poecilorhynchatype of plumage most frequently, in forty-four specimens out of fifty examined, while only six specimens have theA. platyrhynchostype of plumage. Yamashina cites also as evidence favoring his conclusion that hybridization has taken place the results obtained from the crossing of captiveA. platyrhynchosandA. poecilorhyncha. It is his assumption that there has been a resident form ofA. poecilorhynchain the Marianas, apparently resembling closely that which occurs in the Palaus and at Truk (A. p. pelewensis), and that stragglers ofA. platyrhynchosfrom the north occasionally reach the Marianas where hybridization between the two species occurs. Yamashina remarks (1948:123): "The opportunity for hybridization should occur more rarely in the south, and thus more frequent back-crossing of the hybrid with the indigenousAnas poecilorhynchaon Tinian and Guam explains the superabundance there of thepoecilorhynchatype. As the hybridizationshould have taken place more frequently to the north in Saipan, the ratio of the occurrence of theplatyrhynchostype is logically higher there." The Common Mallard (A. p. platyrhynchos) has not been recorded in Micronesia, but according to Yamashina (1948:123) "winters frequently just north of the Marianas in the Bonin and Volcano Islands."

This remarkable explanation for the development of the Marianas Mallard is not questioned by this author, who feels that hybridization may be found to be the cause for other unusual forms of life in island habitats whose ancestry has not been explained. As Yamashina comments, the special environments of islands together with small and restricted populations of animals are factors which could favor such development.

Anas superciliosavar.pelewensisHartlaub and Finsch, Proc. Zool. Soc. London, 1872, p. 108. (Type locality, Pelew Islands.)

Anas superciliosaHartlaub and Finsch, Proc. Zool. London, 1868, pp. 8, 118 (Pelew); Sclater, Proc. Zool. Soc. London, 1869, p. 659 (Pelew); Gray, Hand-list Birds, 3, 1871, p. 82 (Pelew); Salvadori, Ornith. Papuasia, 3, 1882, p. 395 (Pelew); Wiglesworth, Abhandl. und Ber. Zool. Mus. Dresden, no. 6, 1890-1891 (1891), p. 70 (Pelew); Salvadori, Cat. Birds British Mus., 27, 1895, p. 206 (Pelew); Oustalet, Nouv. Arch. Mus. Hist. Nat. Paris, (3), 8, 1896, p. 50 (Palaos).

Anas superciliosa pelewensisDubois, Syn. Avium, 2, 1904, p. 990 (Pelew); Mathews, Birds Australia, 4, 1915, p. 90 (Pelew); Phillips, Nat. Hist. Ducks, 2, 1923, p. 113 (Pelew); Mathews, Syst. Avium Australasianarum, 1, 1927, p. 215 (Pelew); Hartert, Novit. Zool., 36, 1930, p. 112 (Pelew); Peters, Check-list Birds World, 1, 1931, p. 160 (Pelew); Hand-list Japanese Birds, rev., 1932, p. 184 (Palaus, Truk); Hand-list Japanese Birds, 3d ed., 1942, p. 205 (Babelthuap, Peliliu); Amadon, Amer. Mus. Novit., no. 1237, 1943, p. 3 (Palau); Mayr, Birds Southwest Pacific, 1945, p. 286 (Palaus, Truk); Baker, Smithson. Misc. Coll., vol. 107, no. 15, 1948, p. 45 (Peleliu, Truk).

Anas pelewensisFinsch, Journ. Mus. Godeffroy, 8, 1875, pp. 5, 40 (Palau); Schmeltz and Krause, Ethnogr. Abth. Mus. Godeffroy, 1881, p. 407 (Palau); Bolau, Mitteil. Naturhist. Mus. Hamburg, 1898, p. 71 (Palau).

Polionetta superciliosa pelewensisKuroda, in Momiyama, Birds Micronesia, 1922, p. 38 (Pelew).

Anas superciliosa rukensisKuroda, "Gan to Kamo" (Geese and Ducks), 1939, page not numbered, description between pls. 52 and 53 (Type locality, Ruk); Hand-list Japanese Birds, 3d ed., 1942, p. 206 (Truk).

Anas poecilorhyncha superciliosaDelacour and Mayr, Wilson Bull., 57, 1945, pp. 21, 39 (no locality given); Yamashina, Pacific Science, 2, 1948, p. 122 (Palau, Truk).

Geographic range.—Islands of Micronesia, Polynesia, and Melanesia. In Micronesia: Palau Islands—Babelthuap, Peleliu; Caroline Islands—Truk.

Characters.—Adult: A medium-sized duck with upper parts dark brown, feathers edged with buff; top of head blackish merging into gray on hind neck with narrow buff line below; eye-stripe broad and blackish; lower parts uniformly dark brown to gray brown, feathers edged with buff; face, chin and throat light buff with some dark streakings; under wing white; speculum green; bill plumbeous with nail black; legs yellow-brown to yellowish, webs dusky.A. p. pelewensisresemblesA. p. rogersiMathews, but is smaller with a wing length averaging as much as 20 mm. shorter.

Measurements.—As given by Amadon (1943:4) seven unsexed skins from the Palaus, studied by Finsch (1875:40), have wing lengths of 207, 212, 212, 214, 223, 235, 230. For an adult male taken by Coultas at Palau, the exposed culmen measures 45 and the tarsus 37.

Specimens examined.—Total number, 3 males from Palau Islands, AMNH—exact locality not given (Oct. 26, Nov. 25).

Remarks.—A. p. pelewensisis apparently rare in the Palau Islands. Coultas, who visited the Palaus in October to December, 1931, writes (field notes) that he received reports that the birds were present and nested in numbers on fresh water lakes. He took specimens in taro patches and comments that the ducks probably feed at night and have retiring habits during the day. At Peleliu in 1945, the NAMRU2 party received several reports of ducks but failed to find the birds. At Truk, in December, 1945, McElroy of the NAMRU2 party found ducks to be fairly numerous in rice paddies, marshes, and swamps. He observed that the birds roosted at Moen Island at night but that they apparently flew to outlying islands to spend the day. Richards observed ducks on Moen Island on August 28 and 29, 1947, and again in the period from January 19 to February 10, 1948. He saw several flocks of ducks including one containing "about a dozen ducks" at ponds along a roadway and at an airstrip. Kuroda named the population at Truk as distinct in 1939. I have not been able to examine his description and no specimens are available for study, but if the birds at Truk represent an independent colonization (different from that of the birds at Palau) they might exhibit recognizable variation. Amadon (1943:5) has already pointed out that the shortness of the wing of specimens in the Palaus may merit subspecific status for the population. Delacour and Mayr (1945:21) propose that the Palau Gray Duck is a subspecies ofA. poecilorhyncha; this treatment is followed in the present work.

Evolutionary history.—A. p. pelewensis, as Amadon (1943:1) has stated, represents a population of mallards which became separated from the ancestral stock in the Australian or Malayan area and when once differentiated, invaded New Zealand and other parts of Polynesia, Melanesia, and southwestern Micronesia. Amadon points out that its range in the Pacific islands is more or less complimentary to that ofA. oustaletiin the Marianas and the Philippine Mallard (A. poecilorhyncha luzonicaFraser), as well as to the Hawaiian forms (A. wyvillianaSclater andA. laysanensisRothschild).The range ofA. p. pelewensisgives one the impression that its present distribution may be only a stage in a gradual spreading of the species, for it certainly has not yet occupied all habitats suitable for it in southern Micronesia nor elsewhere in Oceania. As in the case ofA. oustaleti,A. p. pelewensisappears to prefer areas of fresh, and possibly brackish, water on the larger islands.

A. p. luzonicais a near relative ofA. p. pelewensisbut has rufous-brown instead of buffy-brown coloring on the chin, throat, sides of head, and superciliary region. The underparts of the Philippine Mallard are much less mottled. The specula are similar. Both of these forms were probably derived from a mallard of theA. p. poecilorhynchatype.

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