Weights.—The author (1948:73) records the weights of 11 adult males as 9.5-14.0 (10.5), of 3 adult females as 8.0-10.0 (9.3).

Specimens examined.—Total number, 61 (33 males, 17 females, 11 unsexed), as follows: Mariana Islands, USNM—Guam, 27 (May 24, 29, 30, June 2, 3, 25, 28, July 12, 18, 19, 20, 23, 26, Sept., Oct. 8); AMNH—Guam, 34 (Jan., March, July, Aug., Sept., Nov., Dec.).

Nesting.—Seale (1901:58) reports the taking of one nestling and three nests with eggs of the bridled white-eye at Guam in the period from May to July. The NAMRU2 party obtained little evidence of nesting in late May to July. Three males taken in the period of June and July had enlarged gonads. Hartert (1898:57) records several nests taken in February and March at Guam. He writes, "The nest is a fairly deep cup, placed in the fork of a branch, woven together of fine grasses and roots, and on the outside ornamented with cobwebs, wool and cottonwood, varying in width from 8 to 5 cm. The clutches consist of 2 or 3 eggs. The eggs are pale blue, like all Zosterops eggs. They measure 18:13, 17:13.2, 17:12.2, 15.5:12:5, 17:13.5, and between these measurements." Coultas obtained specimens with enlarged gonads in August. According to Oustalet (1895:207), Marche found nests and young in May or June.

Remarks.—Kittlitz obtained the Bridled White-eye at Guam, when he visited the island, in March, 1828. He found the birds common and they reminded him of titmice. Marche obtained a series of 21 skins at Guam in August and September, 1887, and in February and March, 1888. Seale (1901:58) observed the birds in flocks of 10 to 20 in roadside bushes and in waste areas. He mentions that their principal foods are insects. The NAMRU2 party found the birds to be restricted to certain areas on Guam, where they were found in small flocks moving about in low trees. They were taken at only five localities, two of these being at the northern end of the island in vegetation along the high, coastal cliffs. The other localities were in the central part of the island in low trees in the uplands. Strophlet (1946:540) found them in grasslands on the foothills. Arvey (field notes) saw a flock of 12 white-eyes at Mount Tenjo in July, 1946.

The white-eye is a very active bird, always moving rapidly through the vegetation or flying across open areas to disappear into scrub foliage. As they move about they make a twittering sound, which is considered to be a flocking call.

Zosterops conspicillata saypani   Dubois

Bridled White-eye

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

Characters.—Adult: Resembles Z. c. conspicillata, but slightly smaller with fronto-loral band more greenish yellow; auriculars olivaceous; orbital ring narrower; upper parts brighter olive; underparts pale yellowish-white; bill darker. Birds from Saipan resemble closely birds from Tinian, but upper parts may be slightly brighter and underparts slightly more yellowish; iris chestnut.

Measurements.—Measurements are listed in table 50. Twenty-three birds from Tinian measure: wing, 51 (50-53); tail, 38 (35-41); full culmen, 12.0 (12.0-13.0); tarsus, 18 (17-18); six birds from Saipan measure: wing, 54 (52-55); tail, 37 (35-39); full culmen, 13.0 (13.0-15.0); tarsus, 18 (17-19). Birds from Saipan are slightly larger than birds from Tinian.

Specimens examined.—Total number, 33 (18 males, 13 females, 2 unsexed), as follows: Mariana Islands, USNM—7 (Oct. 7, 8, 9, 10, 23); AMNH—26 (July, Aug., Sept.).

Nesting.—Yamashina (1932a:398) records the taking of three nests of the Bridled White-eye at Tinian on January 8, 1932. The nests contained one, two, and three eggs, respectively. The color of the eggs is uniformly pale blue; the nests were situated two to four meters from the ground. Oustalet (1895:207) writes that Marche obtained records of nesting at Saipan in the period from May to July. Of 18 birds taken by Coultas at Tinian in September, 1931, one-half of them had enlarged gonads.

Molt.—Specimens examined that were taken in July, August, September, and October have molting plumage.

Remarks.—Marche obtained the first skins of this white-eye at Saipan; he got 23 specimens in May, June, and July, 1887. The population at Saipan was initially considered similar to that at Guam; it was later given subspecific separation by Dubois. The birds at Tinian exhibit some differences from the birds at Saipan, and it is possible that these two populations should be regarded as subspecifically distinct from one another.

In 1931, Coultas (field notes) found this white-eye common at Saipan and Tinian. He writes "The little fellow has adjusted himself to the gardens and shrubs in the villages. He is a seed eater and makes himself at home now around human habitation. I have seen him climbing over potted plants on the window ledges of dwellings. His cheerful little sibilation uttered continuously while at work or while on the wing makes him friends wherever he goes. He is no longer a bird of the forest as he has none here to go to." Several observers in the late war have published notes on this white-eye. Stott (1947:527) writes that he was reminded of the bush-tit (Psaltriparus) when he observed the behavior of this white-eye; Moran (1946:262) writes that it is "Similar in size and behavior to our vireos." Gleise (1945:220) estimated the population of white-eyes at Tinian at 500 plus in 1945. Downs (1946:104-105) found the birds to be abundant at Tinian; he found them in small flocks in low brush or trees and at edges of open fields as well as elsewhere. He saw a white-eye eating "a large green fuzzy caterpillar."

Zosterops conspicillata rotensis   Takatsukasa and Yamashina

Bridled White-eye

Geographic range.—Micronesia: Mariana Islands—Rota.

Characters.—Adult: Upper parts and sides of neck between "warbler green" and "pyrite yellow" becoming lighter on the rump; auriculars light yellowish-green; orbital ring white; fronto-loral band narrowly tinged with yellow; underparts dingy yellow; wing and tail feathers dark with light greenish-yellow edges; upper mandible light brown; lower mandible light yellowish-brown; feet light brown.

Resembles Z. c. conspicillata, but brighter greenish-yellow above; chin and throat yellow like rest of underparts; fronto-loral band tinged with bright yellow; auriculars resemble closely the upper parts in color; narrow orbital ring.

Measurements.—Measurements are listed in table 50.

Specimens examined.—Total number, 5 (3 males, 1 female, 1 unsexed), from Mariana Islands, USNM—Rota (Oct. 18, 20, 22).

Nesting.—Yamashina (1932a:399) records the taking of one nest containing two eggs at Rota on March 7, 1931.

Molt.—Specimens taken in October were in molt.

Remarks.—Oustalet (1895:207) reported on two specimens of white-eye taken at Rota by Marche. He considered them as being similar to the birds at Palau. The birds at Rota were named as a separate subspecies by Takatsukasa and Yamashina in 1931. The NAMRU2 party found the birds to be numerous at Rota in October, 1945.

Zosterops conspicillata semperi    Hartlaub

Bridled White-eye

Geographic range.—Micronesia: Palau Islands—Babelthuap, Koror, Garakayo, Peleliu.

Characters.—Adult: Resembles adult of Z. c. rotensis, but fronto-loral band lighter yellow, and coloring is usually not continuous above; auriculars paler; breast and abdomen paler yellow; maxilla and feet darker; mandible whitish. Resembles adult of Z. c. conspicillata, but brighter greenish-yellow above; coloring of chin and throat like that of rest of underparts; auriculars colored like back; fronto-loral band narrowly tinged with bright yellow and not completely connected above; orbital ring narrow; iris grayish-white.

Measurements.—Measurements are listed in table 50.

Specimens examined.—Total number, 30 (15 males, 14 females, 1 unsexed), as follows: Palau Islands, USNM—Babelthuap, 2 (Nov. 27)—Koror, 4 (Nov. 14, 19)—Garakayo, 4 (Sept. 18, 19); AMNH—exact locality not given, 20 (Oct., Nov., Dec.).

Molt.—All birds examined (taken in September, October, and November) are in molting plumage.

Food habits.—At Garakayo, birds were observed in small flocks feeding in low trees. Two stomachs examined, which were from individuals of these flocks, contained very small seeds.

Remarks.—Oustalet (1895:207) first pointed out the relationship between the Bridled White-eye at Palau and the one at Rota. Hartert (1898:57) thought that the occurrence of the same kind of bird at Palau and at Rota was "very peculiar." It was not until 1931 that Takatsukasa and Yamashina separated the two populations by name.

Coultas (field notes) found the Bridled White-eye to be uncommon in the Palaus in 1931. He observed them in the tops of trees, noting that they were wary and easily frightened away by the shooting of a gun. Coultas writes that he found the birds to be numerous at Peleliu; in 1945, the NAMRU2 party did not find the birds at that island. The only locality where they were found to occur was on the small island of Garakayo where the writer shot four Bridled White-eyes on September 18 and 19. He found two or three small flocks in low trees near the summit of a hill on the island. Approximately 25 birds were in this area.

Zosterops conspicillata owstoni   Hartert

Bridled White-eye

Geographic range.—Micronesia: Caroline Islands—Truk.

Characters.—Adult: Resembles adult of Z. c. semperi, but upper parts darker olive and less yellowish-green; fronto-loral band deeper yellow; auriculars slightly darker; black line on lores and under eye more distinct; underparts deeper yellow; abdomen with greenish tinges. Resembles adult of Z. c. rotensis, but upper parts duller, more green and less yellow; fronto-loral band lighter and less distinct, coloring near that of Z. c. semperi; auriculars darker green; underparts slightly darker, more olive-green and less yellow.

Measurements.—Measurements are listed in table 50.

Specimens examined.—Total number, 23 (12 males, 10 females, 1 unsexed), as follows: Caroline Islands, USNM—Truk, 3 (Feb. 16); AMNH—Truk, 20 (Feb., March, May, Nov.).

Nesting.—Yamashina (1932a:400) records the taking of a nest with one egg at Truk in May. Hartert (1900:2) records nests containing single eggs taken at Truk from May to July. Nests were found in bushes and trees four to eight feet above the ground. The eggs are pale blue. He gives measurements of seven eggs.

Remarks.—Kubary obtained the first specimens of the Bridled White-eye at Truk. Hartert described the population as a new subspecies using material taken by Owston's collectors. The bird was named in honor of Alan Owston. McElroy of the NAMRU2 party visited Truk in December, 1945. He found this white-eye in the mountainous areas at Moen and Udot islands.

Zosterops conspicillata takatsukasai   Momiyama

Bridled White-eye

Geographic range.—Micronesia: Caroline Islands—Ponapé.

Characters.—Adult: Resembles adult of Z. c. semperi, but slightly smaller with fronto-loral area more sulfur-yellow; underparts brighter, especially the coloring of the abdomen and under tail-coverts; iris light chestnut.

Measurements.—Measurements are listed in table 50.

Specimens examined.—Total number, 20 (10 males, 9 females, 1 unsexed) from Caroline Islands, AMNH—Ponapé (Nov., Dec.).

Nesting.—Yamashina (1932a:400) records nests and eggs of Z. c. takatsukasai. The nests, each containing a single egg, were taken on July 10 and 20, 1931. Coultas (field notes) writes that the nest consists of a small, cup-shaped structure of grasses and hair. The natives told him that two eggs were laid. In birds taken by Coultas in November the gonads were beginning to enlarge; specimens taken in December had swollen gonads. From the evidence at hand, it would appear that the Bridled White-eye at Ponapé breeds at two periods of the year, the winter and the summer.

Molt.—Specimens examined, which were taken by Coultas in November and December, are in fresh plumage.

Remarks.—In 1931, Coultas (field notes) found this white-eye to be rare at Ponapé. He obtained almost every one that he saw to get his series of 20 specimens. He found the birds usually in pairs around yellow-flowering bushy trees. A specimen taken by Richards had "small insects" in its stomach.

Zosterops conspicillata hypolais   Hartlaub and Finsch

Bridled White-eye

Geographic range.—Micronesia: Caroline Islands—Yap.

Characters.—According to Hartlaub and Finsch (1872:95), "Upper parts of a pale greyish green, throat and under tail-coverts a pure but very pale whitish-yellow; breast and abdomen of a mixed pale grey and pale yellow; wing- and tail-feathers pale blackish, margined with greenish colour of the back; under wing-coverts and inner margins of remiges white; eye-ring indistinct; beak fuscous, the under mandible paler, except at the tip; feet plumbeous."

Remarks.—No specimen has been examined by me. I am following Stresemann (1931:227) in placing the Bridled White-eye at Yap as a subspecies of Z. conspicillata. This is one arrangement; the committee who prepared the Hand-list of Japanese Birds (1942:192) treat this bird as a separate species. The Japanese probably have more specimens of this bird than anyone else and may be in a better position to judge its taxonomic status. Specimens of this white-eye were taken by Fisher in 1946 at Yap. His report (soon to be published) may throw additional light on the degree of distinctness of Z. c. hypolais. On the basis of published descriptions it is evident that Z. c. hypolais has a few characters in common with other members of the species.

Evolutionary history of Zosterops conspicillata.—The small olive-green and yellow white-eyes of Micronesia have been considered as belonging to several species by authors in the past. As late as 1930, Mathews (1930; 700, 706) placed them in four species. Stresemann (1931a: 227) put them all in the species Z. conspicillata, an arrangement which is being followed in this report. It is evident, however, that these subspecies of Z. conspicillata can be associated into three groups. The author (1948:73) states that Z. c. conspicillata and Z. c. saypani have pale chins and throats, light fronto-loral bands, blackish coloring at the bend of the wings and broad, white orbital rings. Another group, Z. c. rotensis, Z. c. semperi, Z. c. owstoni, and Z. c. takatsukasai, have bright yellow chins and throats, matching the rest of the underparts, obscure fronto-loral bands, which are narrowly tinged with yellow, yellowish coloring at the bend of the wings, and narrow, white orbital rings. Z. c. hypolais apparently falls into a third group by itself, as indicated by the published descriptions. There is apparently some variation in the color of the eyes of these subspecies; they may be either whitish or chestnut in color. The data are insufficient to determine the significance of this color character.

Z. conspicillata is restricted to Micronesia and appears to have little close relationship to other species of the genus. Z. conspicillata shows little affinity to white-eyes to the north and northwest of Micronesia belonging to the species Z. japonica, of which representatives are found in the Bonin and Volcano islands. Z. conspicillata shows greater affinity to species found to the west and to the south of Micronesia.

It may have colonized Micronesia from the south or southeast (Polynesia), even though the species is absent at Kusaie; however, Z. conspicillata shows more relationships to species now living to the westward and the southwestward, and it probably invaded Micronesia from some place in that direction. Z. conspicillata differs from species found in Melanesia and Malaysia chiefly in color of the forehead, lores, fronto-loral band, crown, nape, breast, abdomen, orbital ring, and bill. Also there are differences in the breadth of the orbital ring.

Z. conspicillata shows evidence of relationships with Z. nigrorum of the Philippines and Z. montanus of the Philippines and other parts of Malaysia. Z. nigrorum resembles Z. c. semperi of Palau in size, but is brighter yellow-green above with a darker and less curved bill and brighter underparts. The fronto-loral band and the lores are colored the same in Z. nigrorum and Z. c. semperi. Z. montanus resembles Z. conspicillata especially in size and in shape of the bill. Z. lutea intermedia of the Makassar area shows some affinity to Z. conspicillata, although the bill is heavier. The Micronesia species also bears a close resemblance to Z. griseotincta of the Papuan region. This is especially true of Z. c. takatsukasai at Ponapé; however, Z. griseotincta has a heavier and larger bill. Z. lateralis from southern Melanesia and Australia is not very different from Z. conspicillata aside from its grayish and brownish coloring.

Z. conspicillata probably was derived from an ancestral stock which came to Micronesia from the Philippine or Moluccan area, rather than directly from Melanesia. Z. conspicillata seemingly shows the closest resemblance to Z. nigrorum or to some of its relatives in the Australo-Moluccan area. The subspecies at Palau, Z. c. semperi, appears to be the connecting link. Whether the form at Yap represents an independent colonization is not known; such might also be true in the case of the subspecies at Guam and at Saipan and Tinian. If these are considered as separate colonizations, then the populations can be regarded as separate species. Mayr, (in conversation) has pointed out the affinity of the white-eye at Samoa, Z. samoensis, with Z. conspicillata and suggests that Z. samoensis is derived from the Micronesian species.

Zosterops cinerea cinerea   (Kittlitz)

Micronesian Dusky White-eye