Part 59

Geographic range.--Known from Marcus Island and the western Hawaiian Islands. In Micronesia: Marshall Islands--Bikar.

Remarks.--Yamashina (1940:678) recorded the taking of eight of these terns (5 adult males, 3 adult females) on July 10, 1932, at Bikar in the Marshall Islands. He gives the following measurements: wing, 180.5-188; tail, 104-113.5; exposed culmen, 24-26.5. This is the only known record for the species in Micronesia.

=Anous stolidus pileatus= (Scopoli)

Common Noddy

Sterna pileata Scopoli, Del. Flor. et Faun. Insubr., fasc. 2, 1786, p. 92. (No type locality = Philippines, ex. Sonnerat.)

Sterna stolida Chamisso, in Kotzebue's Voy. "Rurick," 3, 1821, pp. 150, 157 (Marshall Islands); Kittlitz, Kupfertaf. Naturgesch. Vögel, 3, 1833, p. 27, pl. 36, fig. 1 (Mordloks-Inseln); idem, Obser. Zool., in Lutké, Voy. "Le Séniavine," 3, 1836, pp. 286, 299, 308, 309 (Ualan, Lougounor, Ouleai); idem, Denkw. Reise russ. Amer. Micron. und Kamchat., 1, 1858, p. 364, 2, pp. 77, 86 (Ualan); Wiglesworth, Ibis, 1893, p. 212 (Marshalls).

Anous stolidus Hartlaub, Archiv f. Naturgesch., 18, 1852, p. 137 (Mortlock); idem, Journ. f. Ornith., 1854, p. 168 (Carolinen); Gray, Cat. Birds Trop. Is. Pacific Ocean, 1859, p. 59 (Carolines); Finsch and Hartlaub, Fauna Centralpolynesiens, 1867, p. 236 (Mordlocks, Puynipet = Ponapé); Hartlaub and Finsch, Proc. Zool. Soc. London, 1868, pp. 9, 118 (Pelew); idem, Proc. Zool. Soc. London, 1872, pp. 90, 112 (Pelew); Finsch, Journ. Mus. Godeffroy, 8, 1875, pp. 6, 42 (Palau); idem, Journ. Mus. Godeffroy, 12, 1876, pp. 18, 40 (Ponapé); idem, Proc. Zool. Soc. London, 1877 (1878), p. 781 (Ponapé); idem, Journ. f. Ornith., 1880, pp. 295, 307 (Ponapé, Ruck, Kuschai); idem, Proc. Zool. Soc. London, 1880, p. 577 (Ruk, Ponapé, Kuschai); idem, Ibis, 1881, pp. 105, 109, 115, 246, 247 (Kuschai, Ponapé); Schmeltz and Krause, Ethnogr. Abth. Mus. Godeffroy, 1881, pp. 299, 330, 353 (Mortlock, Nukuor, Ruk); Salvadori, Ornith. Papuasia, 3, 1882, p. 455 (Pelews, Carolines, Marshalls); Finsch, Mitth. Ornith. Ver. Wien, 1884, p. 51 (Jaluit, Ponapé); Wiglesworth, Abhandl. und Ber. Zool. Mus. Dresden, no. 6, 1890-1891 (1891), p. 76 (Pelew, Mortlock, Ruk, Nukuor, Ponapé, Ualan, Marshalls); Saunders, Cat. Birds British Museum, 25, 1896, p. 136 (Pelew, Carolines, Marshalls); Oustalet, Nouv. Arch. Mus. Hist. Nat. Paris, (3), 8, 1896, p. 59 (Saypan, Guam, Rota, Agrigan, Hogoleu = Truk, Kushai, Ponapi, Marshalls); Hartert, Novit. Zool., 5, 1898, p. 68 (Guam); Seale, Occ. Papers Bernice P. Bishop Mus., 1, 1901, p. 21 (Guam); Safford, Osprey, 1902, p. 66 (Mariannas); Bryan, Occ. Papers Bernice P. Bishop Mus., 2, 1903, p. 101 (Guam); Schnee, Zool. Jahrbücher, 20, 1904, p. 390 (Marshall-Inseln); Safford, The Plant World, 7, 1904, p. 267 (Guam); idem, Contr. U. S. Nat. Herb., 9, 1905, p. 80 (Guam); Prowazek, Die deutschen Marianen, 1913, p. 100 (Marianen); Takastukasa and Kuroda, Tori, 1, 1915, p. 51 (Ponapé, Ruk); Cox, Island of Guam, 1917, p. 22 (Guam); Uchida, Annot. Zool. Japon., 9, 1918, pp. 484, 488 (Palau, Ponapé); Wharton, Ecol. Monogr., 16, 1946, p. 174 (Guam); Wharton and Hardcastle, Journ. Parasitology, 32, 1946, pp. 292, 296, 306 (Guam, Ulithi).

Anous pileatus Pelzeln, Reise "Novara," Vögel, 1865, pp. 155, 162 (Puynipet = Ponapé).

Anous stolidus pileatus Hartert, Novit. Zool., 7, 1900, p. 9 (Ruk); Wetmore, in Townsend and Wetmore, Bull. Mus. Comp. Zoöl., 63, 1919, p. 183 (Kusaie); Kuroda, in Momiyama, Birds Micronesia, 1922, p. 49 (Guam, Saipan, Pelew, Mortlock, Ruk, Wolea, Nukuoro, Ponapé, Kusaie, Marshalls); Hand-list Japanese Birds, rev., 1932, p. 195 (Koror, Urukthapel, Angaur, Saipan, Guam, Wolea, Truk, Mortlock, Lukunor, Nukuoro, Ponapé, Kusaie, Jaluit, Mille, Aurh, Wotze); Bryan, Guam Rec., vol. 13, no. 2, 1936, p. 24 (Guam); Yamashina, Tori, 10, 1940, p. 678 (Assongsong, Babelthuap); Hand-list Japanese Birds, 3d ed., 1942, p. 219 (Saipan, Assongsong, Guam, Babelthuap, Koror, Urukthapel, Peliliu, Angaur, Wolea, Truk, Mortlock, Lukunor, Nukuoro, Ponapé, Kusaie, Taluit, Mille, Aurh, Wotze); Borror, Auk, 1947, p. 417 (Agrihan); Baker, Smithson. Misc. Coll., vol. 107, no. 15, 1948, p. 56 (Rota, Guam, Peleliu, Ngabad, Ulithi, Truk).

Anous stolidus unicolor? Ridgway, Bull. U. S. Nat. Mus., 50, pt. 8, 1919, p. 547 (Guam).

TABLE 21. MEASUREMENTS OF Anoüs stolidus OF THE PACIFIC AREA

======================================+=====+=========+=========+======== | | | | Exposed LOCATION | No. | Wing | Tail | culmen --------------------------------------+-----+---------+---------+-------- Anoüs stolidus ridgwayi | 18 | 278 | 158 | 41 Isabella, Cocos, Clipperton Islands | | 260-295 | 147-166 | 38-42 | | | | Anoüs stolidus galapagensis | 11 | 277 | 151 | 40 Galapagos Islands | | 274-282 | 142-160 | 38-42 | | | | Anoüs stolidus pileatus | 35 | 281 | 162 | 42 Hawaiian Islands: Nihoa to Midway | | 268-299 | 149-176 | 38-40 | | | | Wake Islands | 8 | 278 | 159 | 41 | | 273-285 | 152-170 | 39-43 | | | | Mariana Islands: Guam, Rota | 12 | 280 | 167 | 41 | | 275-288 | 159-187 | 39-43 | | | | Palau Islands | 9 | 278 | 161 | 41 | | 268-283 | 155-166 | 39-42 | | | | Caroline Islands | 41 | 282 | 164 | 42 | | 270-291 | 150-173 | 39-45 | | | | Marshall Islands | 3 | 282 | 164 | 42 | | 270-289 | 154-174 | 41-43 | | | | Ellice, Phoenix, Danger, Suvarov | 27 | 284 | 162 | 41 Islands | | 265-295 | 152-174 | 39-44 | | | | Christmas Island | 13 | 287 | 162 | 43 | | 280-292 | 152-174 | 40-46 | | | | Marquesas Islands | 19 | 282 | 163 | 42 | | 275-291 | 155-170 | 40-43 | | | | Tuamotu Archipelago | 38 | 287 | 165 | 42 | | 277-299 | 154-173 | 39-46 | | | | Society, Austral, Cook, Rapa | 16 | 290 | 290 | 43 Islands | | 280-301 | 155-173 | 40-45 | | | | Oeno, Henderson, Ducie, Easter | 6 | 293 | 164 | 44 Islands | | 154-175 | 154-175 | 41-45 | | | | Samoa, Fiji, Tonga | 19 | 285 | 164 | 42 | | 153-173 | 153-173 | 39-44 | | | | Kermadecs, Norfolk | 23 | 276 | 158 | 41 | | 269-289 | 148-173 | 38-43 | | | | New Hebrides, Solomons, New Guinea | 31 | 278 | 158 | 41 area | | 265-287 | 150-172 | 3 -44 | | | | Northwest Australia | 9 | 263 | 145 | 40 | | 258-267 | 138-152 | 38-42 | | | | South China Sea area, Strait of | 4 | 271 | 153 | 39 Malacca | | 262-278 | 148-257 | 37-40 | | | | Riu Kius, Japan | 5 | 268 | 148 | 39 | | 259-275 | 143-155 | 37-40 | | | | Indian Ocean area: Seychelles, | 20 | 276 | 154 | 41 Aldebra, Providence, Somaliland | | 270-286 | 146-164 | 39-42 --------------------------------------+-----+---------+---------+--------

Geographic range.--Islands in the Indian Ocean east to tropical parts of western and central Pacific. In Micronesia: Mariana Islands--Agrihan, Asuncion, Saipan, Rota, Guam; Palau Islands--Kayangel, Babelthuap, Koror, Urukthapel, Ngabad, Peleliu, Angaur; Caroline Islands--Ulithi, Truk, Wolea, Mortlock, Lukunor, Nukuoro, Ponapé, Kusaie; Marshall Islands--Jaluit, Mille, Aurh, Wotze, Bikini, Kwajalein.

Characters.--Adult: A large, dark-brown tern with grayish crown and whitish forehead; line above eye white; crescent of white on lower eyelid; lores blackish; bill black; feet brownish, iris dark.

Immature: Resembles adult, but lighter and browner and top of head grayish-brown.

A. s. pileatus resembles A. s. ridgwayi, but darker and less brownish, although not so dark as A. s. galapagensis; forehead and crown usually duller; length of wing and tail average larger (282 and 161) than in A. s. ridgwayi (278 and 158) and A. s. galapagensis (277 and 151).

Measurements.--Measurements of the Common Noddy of the Pacific area are listed in table 21.

Weights.--In 1948 (1948:56) I listed the weights of specimens from Guam and Rota as follows: four adult males 187-204 (197); three adult females 177-203 (189).

Specimens examined.--Total number, 92 (43 males, 39 females, 10 unsexed), as follows: Mariana Islands, USNM--Guam, 7 (May 24, June 15, July 6, 21)--Rota, 3 (Oct. 18, 24); AMNH--Guam, 4 (April 21, 27, Aug. 18)--Asuncion, 1 (Jan. 18); Palau Islands, USNM--Peleliu, 2 (Sept. 1)--Ngabad, 1 (Sept. 11); AMNH--exact locality not given, 6 (Nov. 3, 8); Caroline Islands, USNM--Ulithi, 3 (Aug. 15)--Kusaie, 1 (Feb. 8); AMNH--Truk, 15 (Feb. 1, 8, 25, March 10, May 6, June 12, 13, Nov. 25, Dec. 25)--Ponapé, 20 (Dec. 3, 5, 8, 12, 15)--Kusaie, 24 (Jan., March 10-30, April 1-10); Marshall Islands, USNM--Bikini, 5 (Feb. 28, March 2, 19).

Nesting.--Murphy (1936:1152) writes that the Atlantic subspecies, A. s. stolidus, breeds in tropical localities every month of the year, although there may be a part of the resident population away at sea at any given time. In the Pacific area, Kirby (1925:187) found nests "on platforms of sticks built on tufts of grass" at Christmas Island in August. In Micronesia, Coultas obtained young birds at Kusaie in January and April and commented (field notes) that they probably nest "spasmodically at all times of the year." At Ponapé, Coultas observed nests in high trees in December, and birds obtained by him in that month had enlarged gonads. At Bikini, Morrison obtained eggs on March 2 and 19, and young on March 19. At Palau, Coultas took one female tern in postnatal molt on November 8. Adults obtained by him in that month had enlarged gonads. At Ulithi, the NAMRU2 party recorded one nest containing a single egg on August 21. At the same atoll the NAMRU2 party received reports of a large colony of nesting noddys in May to July, 1945. In the following August few noddies were seen by the NAMRU2 party. McElroy found nests on cliffs and in coconut trees at Truk in December, 1945. Hartert (1900:10) reports on eggs taken at Truk in the period from March to July 1. The NAMRU2 party observed birds carrying nest materials at Peleliu on August 28 but failed to find the nests. At Guam, the writer found terns in numbers varying from 4 to 75 in May to July, 1945, along the rocky cliffs but no evidence of nesting activity was obtained. Strophlet (1946:537) reports that nests may have been present on Orote Peninsula at Guam on December 13, 1945. Coultas (field notes) is of the opinion that the birds do not nest at Guam but do nest farther north in the Marianas. Borror (1947:417) found two colonies at Agrihan on August 10, 1945. Thus, there are records of nesting in nine months of the year in Micronesia; although I suspect that the larger flocks of terns have more regular breeding habits correlated with their pelagic feeding activities. "Stragglers" probably nest irregularly.

Food habits.--The author (1948:56) records small fish and crustaceans in stomachs of terns taken at Ulithi and Peleliu. At Ypao Point, Guam, birds were seen to fly back and forth in the day from their roosts on the sea-cliffs. On one occasion I saw these birds feeding approximately a half mile from shore.

Parasites.--Wharton (1946:174) and Wharton and Hardcastle (1946:292, 296, 306) list the following species of chiggers (Acarina) from the Common Noddy from Guam and Ulithi: Neoschöngastia bougainvillensis, N. americana solomonis, N. egretta, Acariscus pluvius, and A. anous. Uchida (1918:484, 488) found the bird louse (Mallophaga), Nirmus separatus, on terms at Palau and at Ponapé he found Colpocephalum milleri on the bird. Bequaert (in litt.) has identified a fly (Hippoboscidae) as Olfersia aenescens from a tern from Rota.

Remarks.--Of the Common Noddy Tern of the Pacific area, three subspecies are recognized by Peters (1934:346-347). Anoüs stolidus ridgwayi is known from islands off the western coast of Mexico and Central America; A. s. galapagensis is recorded from the Galapagos Archipelago; and A. s. pileatus is found on tropical islands throughout the Pacific and west to Madagascar and the African coast in the Indian Ocean. These subspecies differ from one another principally in color, as noted by Ridgway (1919:545); A. s. galapagensis is the darkest form, A. s. ridgwayi is less blackish and more brownish in color of body, and A. s. pileatus is between the two in coloring. A. s. pileatus averages larger in length of wing and tail, but these measurements do not appear to be significant from a taxonomic standpoint.

As shown in table 21, measurements of length of wing for specimens from throughout most of the Pacific area are almost the same. Length of tail is correspondingly uniform. There is a gradual increase in size of birds in the Tuamotus and Societies and east to Easter Island. In this region the average measurement for length of wing is 293 millimeters. The lengths of wing and tails are shorter in specimens from the Kermadecs and Norfolk Island, which may indicate relationships with the smaller birds of the Australian area, Western Melanesia and possibly Malaysia and the Riu Kiu Islands. I am unable to determine the subspecific status of the birds from the Kermadecs and Norfolk Island, because of the lack of sufficient material from the Australian region and Malaysia. Possibly Mathews' name, A. s. gilberti, is valid for the noddys of Australia and also for the birds at Norfolk and the Kermadecs. The small-sized birds of the Riu Kiu Islands have been designated as A. s. pullus by Bangs. When specimens from the type locality of A. s. pileatus in the Philippine Islands are available, the true relationships of the populations from Micronesia and the other areas in the Pacific can be ascertained.

The tern found in the Hawaiians has the palest body and the most chalky-white forehead of any of the birds of the Pacific. Bryan (1903:101) found terns from Marcus Island to agree with specimens from Guam and to be "slightly darker" than birds from Midway and Laysan in the Hawaiian chain. The birds from the Riu Kius are darker and thus similar to the few specimens seen from Malaysia. Birds from Polynesia and Melanesia possess the most sooty underparts while those from Micronesia are only slightly less pale. This condition also seems to be true for the birds in the Australian area and for specimens seen from islands in the Indian Ocean. With fading, or wear, or both, there is a change from dusky black to dusky brown in the plumage; effort was made by me to compare specimens with relatively similar conditions of plumage. In summary, the systematic position of the Common Noddy Terns of the Pacific seemingly depends on the characteristics of specimens from the type locality in the Philippines. When topotypes are available for study, they may be found to be nearer the darker forms of Malaysia or may tend toward the paler, oceanic forms. The Hawaiian population probably is distinct.

In Micronesia the Common Noddy Tern is not a conspicuous bird except during its breeding period. Probably it spends most of its life at sea, being unlike Gygis alba in this respect. Large flocks seem less wary of man than are small groups and singles, which are often easily disturbed. Birds of this species appear to prefer the low atolls and offshore islets where both tall vegetation and bare ground are utilized for nesting or roosting. At Ponapé, Coultas (field notes) observed the birds to fly to sea at daybreak and to begin to return to their roosts by 4:00 pm. Wallace (field notes) observed similar activities at Kwajalein in May, 1944, where he saw approximately forty individuals in a flock with Gygis alba.

Anoüs stolidus is divided naturally into an Atlantic subspecies, which is distinguished by its browner color, and into several subspecies which are distinguished by their blacker color in the Pacific and Indian oceans. Whether the genus and species evolved in the Atlantic or in the Pacific region is not known. If it were the Pacific region, the center of differentiation may very well have been the islands of Oceania. There, relatively little variation is observable within populations covering a large area. To the eastward, birds along the American coast are darker or lighter, to the northward, the birds of Hawaii are paler, to the southward and southwestward, the birds are smaller and to the westward, the birds are smaller and darker. The virtual absence of ground-living, predatory animals which might prey on nesting colonies has probably been a reason for the lack of discrimination by this tern in selecting breeding sites. This is probably true of other birds which nest in colonies.

=Anous tenuirostris marcusi= (Bryan)