Part 72

Specimens examined.--Total number, 96 (50 males, 38 females, 8 unsexed) as follows: Mariana Islands, USNM--Guam, 29 (Mar. 18, April 4, 17, May 20, 28, June 2, 9, 13, 14, 15, 20, 23, 24, 27, 28, July 2, 6, 10, 23, Aug. 11, 21)--Rota, 6 (Oct. 20, 22, 25, 26, Nov. 1, 2)--Tinian, 4 (Oct. 24, 26); AMNH--Guam, 40 (Jan. 17, 30, Feb. 12, 20, March 3, 5, 7, 11, 13, 23, April 13, 19, June 13, 15, July 10, 25, Aug. 4, 10, 11, 13, 15, 18, 20, 21, 22, Sept. 4, Dec. 26, 30)--Tinian, 8 (Sept. 7, 10, 11, 12, 13)--Saipan, 6 (July 13, 15, Aug. 24, Sept. 7, 8)--Asuncion, 3 (Jan. 18, Feb. 7, June).

Nesting.--The NAMRU2 party found the ground dove nesting at Guam in the winter and spring months beginning in late January. Nests were observed in tall trees, many of which were well isolated from other trees and vegetation. On February 10 a nest was discovered in a breadfruit tree near one of the NAMRU2 barracks on Oca Point. It was approximately 50 feet above the ground. On February 26 I found pieces of egg shell beneath the tree. Occasionally during the day, the male, but never the female, was observed sitting on this nest. On February 10, a dove (the male) was observed building a nest in a large banyan tree at Oca Point. Another nest was being constructed by a female on March 7. On March 17 a young female dove, just beginning to fly, was taken; another was found on April 3. Adult birds with enlarged gonads were taken in April, May, June, and July. Marche, according to Oustalet (1895:224), obtained eggs in May, 1887.

Food habits.--Stomachs of doves taken at Guam contained fruits and fruit parts. On March 9, a dove was observed feeding on the berries of the shrub known as "inkbush." This appeared to be a favorite food. Seale (1901:42) also mentions that this berry is a preferred food.

Parasites.--Wharton (1946:174) lists the chigger (Acarina), Trombicula sp., from the ground dove at Guam.

Remarks.--At Guam, the NAMRU2 party observed the ground dove to be fairly common in 1945. Along roadways, the present author (1947b:124) found that individuals of this species comprised 2.5 percent of the total population of birds observed, and the ground dove was seen on 31.2 percent of 125 road counts made. The male was much more in evidence than the female and was frequently seen flying high over the roadways and jungle areas; eighty percent of the ground doves seen while road-counts were being made were males. The female was found less frequently; it was a less conspicuous bird and was seen only occasionally in flight. Neither sex appeared to have the secretive, terrestrial habits of G. canifrons of the Palau Islands. On the basis of our observations at Guam, I would say that the name "ground dove" for the bird at Guam is not descriptive. The birds were found to spend considerable time in tall trees; the closest that I saw them to the ground was when they were feeding only three to four feet from the ground in the ink berry bushes.

The call note of this dove is much like that of the Palau Ground Dove; Seale (1901:42) describes it as follows, "These pigeons seem to prefer the deep jungle, from whence their deep low moan, like the sound of a man dying in great distress, comes with a weird uncanny effect, heightened by the gloom and darkness of the unknown forest.... This sound, which always seems to come from a long distance, is very misleading, and one is considerably surprised to find he is perhaps within a few feet of the bird." Seale writes that they were very common on Guam in 1900. In 1931, Coultas found the dove "quite common at the north end of the island." The bird apparently prefers the dense forest or second growth brushy areas, but was found also in the partly cleared areas surrounding the NAMRU2 headquarters at Oca Point in 1945. At Rota, the NAMRU2 party found the birds to be numerous in 1945. Coultas observed only a few birds on Tinian in 1931; Downs (1946:96) found only a small population at this island in 1945. The extensive cultivation and clearing activities at Tinian have removed much of the habitat suitable for these, as well as other birds. At Saipan, Stott (1947:526) writes that the bird is common on "brush-covered hillsides and semi-wooded country." There is little information published regarding the status of this dove in the northern Marianas.

=Gallicolumba xanthonura kubaryi= (Finsch)

White-throated Ground Dove

Phlegoenas Kubaryi Finsch, Journ. f. Ornith., 1880, p. 292. (Type locality, Ruck and Ponapé.)

Phlegoenas erythroptera Bonaparte, Consp. Avium, 2, 1854, p. 89 (Carolines); Reichenbach, Tauben, 1862, p. 41 (Carolines); Finsch, Proc. Zool. Soc. London, 1877 (1878), p. 780 (Ponapé); idem, Ibis, 1881, p. 115 (Ponapé); Schmeltz and Krause, Ethnogr. Abth. Mus. Godeffroy, 1881, pp. 281, 353 (Ponapé, Ruk); Tristram, Cat. Birds, 1889, p. 41 (Ruk).

Phlegoenas kubaryi Reichenow and Schalow, Journ. f. Ornith., 1881, p. 75 (Ruk, Ponapé); Wiglesworth, Abhandl. und Ber. Zool. Mus. Dresden, no. 6, 1890-1891 (1891), p. 55 (Ruk, Ponapé); Hartert, Novit. Zool., 7, 1900, p. 8 (Ruk, Ponapé); Matschie, Journ. f. Ornith., 1901, p. 113 (Ruck, Ponapé); Kuroda, in Momiyama, Birds Micronesia, 1922, p. 53 (Ruk, Ponapé).

Phlogoenas erythroptera Finsch, Proc. Zool. Soc. London, 1880, p. 576 (Ponapé, Ruk); Takatsukasa and Kuroda, Tori, 1, 1915, p. 52 (Ruk).

Phlogoenas kubaryi Salvadori, Cat. Birds British Mus., 21, 1893, p. 599 (Ruk, Ponapé); Oustalet, Nouv. Arch. Mus. Hist. Nat. Paris, (3), 7, 1895, p. 227 (Caroline = Truk); Bolau, Mitteil. Naturhist. Mus. Hamburg, 1898, p. 68 (Ruck); Reichenow, Die Vögel, 1, 1913, p. 331 (Karolinen).

Phlegaenas kubaryi Christian, The Caroline Islands, 1899, p. 357 (Ponapé).

Gallicolumba kubaryi Mathews, Syst. Avium Australasianarum, 1, 1927, p. 74 (Caroline Is.); Hand-list Japanese Birds, rev., 1932, p. 189 (Truk, Ponapé); Peters, Check-list Birds World, 3, 1947, p. 136 (Ruk, Ponapé); Mayr, Proc. 6th Pacific Sci. Congr., 4, 1941, p. 204 (Ponapé); Bequaert, Mushi, 12, 1939, p. 81 (Ponapé); idem, Occ. Papers Bernice P. Bishop Mus., 16, 1941, p. 266 (Ponapé); Hand-list Japanese Birds, 3d ed., 1942, p. 211 (Truk, Ponapé).

Gallicolumba xanthonura kubaryi Mayr, Birds Southwest Pacific, 1945, p. 290 (Truk, Ponapé); Baker, Smithson. Misc. Coll., vol. 107, no. 15, 1948, p. 62 (Truk).

Geographic range.--Micronesia: Caroline Islands--Truk, Ponapé.

Characters.--Adult male: Resembles adult male of G. x. xanthonura, but larger with crown, nape, and hind neck sooty-black; upper back and lesser upper wing-coverts purplish-violet, extending lower on back than in G. x. xanthonura.

Adult female: Resembles adult male, but smaller and paler with upper back glossy, bronze-green margined with purplish-violet; lower back and rump glossy, olive-green; upper tail-coverts greenish-brown; central tail feathers blackish-brown; innermost secondaries bright, glossy green tinged with bluish.

Measurements.--Measurements are presented in table 28.

Specimens examined.--Total number, 21 (9 males, 11 females, 1 unsexed), as follows: Caroline Islands, USNM--Truk, 1 (July); AMNH--Ponapé, 13 (Nov., Dec.)--Truk, 7 (Jan., Feb., May).

Nesting.--At Ponapé in November and December, Coultas obtained specimens which had enlarged gonads. He did not find the nest of this bird but writes (field notes) that the natives told him that the nest is placed in the top of the tree fern 10 or 15 feet above the ground. In contrast, the ground dove at Guam may select a nesting site considerably higher in the tree. Coultas reports that one egg is laid by C. x. kubaryi.

Food habits.--Coultas (field notes) writes that the bird feeds and lives on the ground at Ponapé. He lists food as small snails, seeds, and worms.

Parasites.--Bequaert (1939:81 and 1941:266) records the fly (Hippoboscidae), Ornithoctona plicata, from the ground dove at Ponapé.

Remarks.--Coultas (field notes) writes that in 1930 the ground dove at Ponapé was rare in the forested areas and generally found more along the sea coast and in the upland valleys. Coultas describes its call as an infrequent shrill, whistle-like call. He writes that hunting by the Japanese and natives was reducing the population of G. x. kubaryi at Ponapé in 1930. In 1945, McElroy of the NAMRU2 party found the dove at Truk on forested slopes in tall trees, and reported that its habits at Truk were similar to those of C. x. xanthonura at Guam. In 1947-1948, Richards noted (in litt.) that the dove at Ponapé was rare (he saw only one specimen). At Truk, he found the bird to be "rather common" in thickets, dry gullies, and flying over grassy slopes. He found the bird near sea level, never in country above 300 feet in altitude and not in deep forest. I offer no explanation for the conflicting reports concerning the habits of this species, unless it be that the bird is capable of varying its habits to fit particular habitats; for example, in jungle areas it may be ground-living and in open woodlands it may be tree-living.

Evolutionary history of Gallicolumba in Micronesia.--There have been two unrelated invasions of Micronesia by the genus Gallicolumba. One invasion established G. canifrons at the Palau Islands. The other established the populations of G. xanthonura in the Caroline and Mariana islands, Mayr (1936:4) points out that G. xanthonura is related to G. jobiensis (New Guinea and Northern Melanesia), G. erythroptera (Society and Tuamotu islands), and G. rubescens (Marquesas Islands). This group may be regarded as a superspecies. The adults of G. jobiensis, the male and female, resemble one another. In both, the head, neck, and auriculoloral stripes are sooty-black; the eye stripe, chin, throat, and breast are white; the abdomen is dark; and the upper parts are blackish with a coppery sheen. Immatures are rusty-brown. G. xanthonura is closely related to G. jobiensis, and they conceivably, along with G. erythroptera, might be considered conspecific. The close relationship between the G. xanthonura in Micronesia and G. erythroptera has been noted by Oustalet (1896:71). Among named kinds, G. x. kubaryi most closely resembles G. jobiensis with sooty-black coloring present on the head. The male and female of G. x. kubaryi closely resemble each other, although immature type of plumage may occur in adult females as indicated by the immature plumage of a bird containing well-developed eggs taken at Ponapé by Coultas.

In G. x. xanthonura the male lacks the sooty-black head and has lost some of the coppery sheen from the middle of the back. The female has taken on the immature type of plumage, except for occasional near-male type plumage. In G. erythroptera the male has lost some of the sooty-black coloring on the forehead, anterior crown, and loral area and some of the coppery sheen in the middle of the back. The female of G. erythroptera resembles the female of G. x. xanthonura except that the throat and breast are faintly outlined by the brownish color. The head and malar stripe are also outlined in this manner. Some females have some coppery gloss on the shoulder and a few white feathers on the breast; these may be considered as in the near-male type of plumage.

The tendencies in the evolution of these insular populations of Gallicolumba include a reduction of sooty-black on the head and a reduction of coppery gloss on the back of the male and the reduction of malelike plumage in the female. G. rubescens of the Marquesas Islands is smaller and darker. It retains the coppery gloss on the back and has, in addition, a white bar on the tail and one on the wing. On the basis of color and structural characters, it is apparent that this superspecies of Gallicolumba has evolved from a center of evolution in the region of New Guinea (as shown in figure 14) with a colonization of Micronesia, from which (probably from G. x. kubaryi) an invasion of eastern Polynesia occurred establishing G. erythroptera in the Society and Tuamotu islands, although it is also possible that G. erythroptera may have reached Polynesia by way of a more direct route from Melanesia. Such a pathway of colonization as that just described is not unusual since representatives of other genera including Acrocephalus, Myzomela, and Zosterops may have followed similar paths of dispersal from Micronesia into Polynesia. Apparently a population isolated in the Marquesas has evolved the distinctive G. rubescens.