Nocturnal Activity of Caged Resident and Migrant Silvereyes (Zosteropidae: Aves)

Abstract

Night‐activity patterns of individually‐caged grey‐breasted silvereyes Zosterops lateralis of resident and migrant status were investigated. True migratory restlessness or ‘Zugunruhe’ was exhibited by some individuals, but there was also considerable ‘noise’ in the data caused by cageing and neighbouring disturbance. In general, ‘Zugunruhe’ took place from about 2 h before, to about 4 h after ‘sunrise’, and both the daily timing and annual duration of Zugunruhe were consistent with the migration pattern observed in the field. A total of 42 % of resident birds from Tasmania, 77 % of migrant birds from Tasmania and 90 % of migrant birds from the mainland were considered to have exhibited true ‘Zugunruhe’, while none of the resident birds from Brisbane were considered to have displayed it. A few individuals spontaneously developed ‘Zugunruhe’ in the absence of other birds, but many birds (both residents and migrants) displayed no elevated night unrest when placed in a room on their own, although displaying unrest when placed among birds exhibiting ‘Zugunruhe’. The migration of the silvereye probably has a genetic basis, but whether an individual migrates or not is also influenced by social factors which differ in magnitude between individuals.

Under a neighbour's influence: public information affects stress hormones and behaviour of a songbird

“…It is probable that at least some public information is gathered using inadvertent social information; however, information may also be produced intentionally by group members. For example, captive migratory silvereyes (Zosterops lateralis) can induce migratory behaviours in non-migrant birds, apparently through stimulation by night-time vocalizations (Chan 1994). Observations in captive and free-living environments suggest that crossbills experiencing poor foraging conditions vocalize with greater intensity (Smith et al 1999 .…”

Bird migration in the southern hemisphere: a review comparing continents

“…These diurnal migrants use both celestial and magnetic cues for orientation like well-studied nocturnal northern migrants (Wiltschko and Wiltschko 1995). Like the Yellow-faced Honeyeater, the partially migratory Tasmanian population of Silvereyes display migratory restlessness and premigratory fattening (Chan 1994(Chan , 1995 and orientation appropriate to the season of migration using both celestial and magnetic cues (Wiltschko et al 1998a(Wiltschko et al , 1998b(Wiltschko et al , 2001). In both species, endogenous control mechanisms regulate migration and the seasonal cycle, as the experiments with migratory restlessness and diet revealed (Munro 2003).…”

Daily and seasonal activity patterns of partially migratory and nonmigratory subspecies of the Australian silvereye, Zosterops lateralis, in captivity

“…In this study we employed the established and common classification scheme for southeastern silvereyes developed by Mees (1969), which was also used by Chan (1994Chan ( , 1995, instead of the more recent classification scheme of ultrataxa proposed by Schodde and Mason (1999). This scheme allows for the easy distinction between both subspecies on the basis of plumage (e.g., flank and throat color).…”

“…This is particularly the case in Australia, where many of the migrants are partial and/or short distance migrants (Nix 1976;Chan 2001;Griffioen and Clarke 2002). To date, studies on Australian passerines have been conducted on two unrelated species from southeastern Australia, the diurnally migratory yellow-faced honeyeater, Lichenostomus chrysops (Meliphagidae), (Munro and Munro 1998) and the Australian silvereye, Zosterops lateralis (Zosteropidae), (Chan 1994(Chan , 1995, which displays both diurnal and nocturnal migration. Both species migrate along the east coast of Australia (up to a maximum distance of around 1,700 km) (Robertson 1971;Lane 1972a) and are regarded as short distance migrants.…”

“…Previous studies on migratory activity in both subspecies were conducted by Chan (1994Chan ( , 1995 and found that some of the migratory birds spontaneously developed increased nocturnal locomotor activity during the migratory periods, suggesting endogenous stimuli. However, some of his results are difficult to interpret, such as small amounts of nocturnal activity outside the migratory periods and in nonmigratory birds.…”