Sounds and Vocal Behavior

Development

Food begging by Saipan juveniles has been observed year-round (47 Craig, R. J. (1996). Seasonal population surveys and natural history of a Micronesian bird community. Wilson Bulletin 108(2):246–267. Close ).

Vocal Array

Song

Song was first described from Tinian as involving an extended series of siskin (Spinus)-like call notes (2 Marshall, J. T. (1949). The endemic avifauna of Saipan, Tinian, Guam and Palau. Condor 51(5):200–221. Close ). More recently, Guam birds were described as having a relatively complex song consisting of a lilting, buzzy zeeip-zee-zee-zoo-zip (35 Pratt, H. D., P. L. Bruner, and D. G. Berrett (1987). A Field Guide to the Birds of Hawaii and the Tropical Pacific. Princeton University Press, Princeton, NJ, USA. Close ). Males sing with their throats puffed (59 Smith, O., and T. Wassmer (2016). An ethogram of commonly observed behaviors of the Endangered Bridled White-eye (Zosterops conspicillatus) in a zoo setting. Wilson Journal of Ornithology 128(3):647–653. Close ).

Calls

On Guam, an early account of the Bridled White-eye’s voice described flight calls as being like those of the House Sparrow (Passer domesticus) but not as loud or harsh. The high-pitched location notes were reported as being constantly uttered, apparently serving to keep flock members together, and were more intensely given by flock stragglers (17 Seale, A. (1901). Report of a mission to Guam. Occasional Papers of Bernice P. Bishop Museum 1:17–128. Close ). Flocking calls also were described as twittering sounds (1 Baker, R. H. (1951). The avifauna of Micronesia. Its origin, evolution, and distribution. University of Kansas Publications, Museum of Natural History 3(1):1–359. Close ) and sounding like insects, with the voice almost a buzz (54 Hartin, M.H. (1961). Birds of Guam. Elepaio 22:34−38. Close ). Birds made flocking calls in flight, presumably as a contact note. These chipping calls intensified when a group landed in vegetation, although calls became less frequent as birds began to forage. The chipping call, uttered at various intensities, was the only vocalization heard (16 Jenkins, J. M. (1983). The native forest birds of Guam. Ornithological Monographs 31:1–61. Close ). In 1981, low volume contact calls were frequent, particularly when groups were moving between trees (55 Engbring, J., and F. L. Ramsey (1984). Distribution and Abundance of the Forest Birds of Guam: Results of a 1981 Survey. United States Fish and Wildlife Service, Washington, D.C. and Honululu, HI. Close ). Birds also were described as making rolling, buzzy call notes best characterized as cheep or tszeeip (35 Pratt, H. D., P. L. Bruner, and D. G. Berrett (1987). A Field Guide to the Birds of Hawaii and the Tropical Pacific. Princeton University Press, Princeton, NJ, USA. Close ).

On Tinian, a “confusion chorus” heard upon the arrival of a predatory Mariana Kingfisher (Todiramphus albicilla) consisted of call notes delivered at maximum intensity and frequency by all flock members. It lasted for ~one minute, during which time birds remained stationary. They appeared to respond in this manner only to the kingfisher in flight. After the kingfisher perched, the confusion chorus abated, and birds resumed foraging (2 Marshall, J. T. (1949). The endemic avifauna of Saipan, Tinian, Guam and Palau. Condor 51(5):200–221. Close ).

Observations made in 1988 on Saipan showed that while birds foraged in flocks, individuals communicated via series of chit-chit notes, although a second group of whining vocalizations were given commonly. These whining notes also were used in agonistic interactions, such as those involving chases between a pair of birds and a third individual, and when birds mobbed a Mariana Kingfisher (49 Craig, R. J. (1989). Observations on the foraging ecology and social behavior of the Bridled White-eye. Condor 91(1):187–192. Close ).

Contact calls recorded in January−February 1988 on 270 min of bird sounds from Saipan limestone forest and Leucaena thickets consisted of a series of or single high-pitched, elongated chdddeer or chdddeet notes, which correspond to siskin (Spinus)-like notes described by Marshall (2 Marshall, J. T. (1949). The endemic avifauna of Saipan, Tinian, Guam and Palau. Condor 51(5):200–221. Close ), whining, thin, high-pitched eeeer notes, and also shorter, high-pitched chit notes. Contact calls recorded over 90 min in January 1989 from Tinian limestone forest and Leucaena thickets showed no obvious differences with those from Saipan (R.J. Craig, unpublished data). Similarly, birds on Aguiguan showed no noticeable differences in vocalizations with birds from Saipan and Tinian (36 Engbring, J., Ramsey, F.L. and Wildman, V.J. (1986). Micronesian Forest Bird Survey, 1982: Saipan, Tinian, Agiguan, and Rota. US Fish & Wildlife Service Report, Honolulu, Hawaii. Close , R.J. Craig, personal observation).

Geographic Variation

Boesman (61 Boesman, P. (2016). Notes on the vocalizations of Bridled White-eye (Zosterops conspicillatus). HBW Alive Ornithological Note 263. In: Handbook of the Birds of the World Alive. Lynx Edicions, Barcelona. Close ) claimed that subspecies saypani has a more extensive vocabulary, including medium-pitched chirps, low-pitched chirps, high-pitched notes, nasal (i.e., whining) notes, and song-like high-pitched phrases, whereas subspecies conspicillatus apparently produced only buzzy and high-pitched notes. However, observations on Guam birds by Pratt et al. (35 Pratt, H. D., P. L. Bruner, and D. G. Berrett (1987). A Field Guide to the Birds of Hawaii and the Tropical Pacific. Princeton University Press, Princeton, NJ, USA. Close ) did not support the occurrence of such a limited vocal repertoire. Moreover, review of 360 minutes of audio recordings of Saipan and Tinian birds did not support the occurrence of medium and low-pitched chirps in this subspecies (R.J. Craig, unpublished data). However, Saipan and Tinian birds appear to differ in voice from those on Guam, with subspecies saypani described as making high-pitched plaintive siskin (Spinus)-like calls and rough chilp-chilp calls like those of a House Sparrow. The high-pitched calls were absent from the repertoire of subspecies conspicillatus (2 Marshall, J. T. (1949). The endemic avifauna of Saipan, Tinian, Guam and Palau. Condor 51(5):200–221. Close ). Similarly, Saipan and Tinian birds have been described as having calls that are higher pitched and less buzzy than Guam birds, with chirps often uttered rapidly and organized into a loose song (35 Pratt, H. D., P. L. Bruner, and D. G. Berrett (1987). A Field Guide to the Birds of Hawaii and the Tropical Pacific. Princeton University Press, Princeton, NJ, USA. Close ).

None reported.