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Zosterops lateralis Sundevall, 1850: 101. VERBATIM TYPE LOCALITY: “ Hab. in Caffraria superiore, campestri, prope Vaal Revier (26- 27°). ” CURRENT STATUS: Synonym of Zosterops pallidus Swainson, 1838; Zosteropidae (Dickinson & Christidis 2014: 520). Sometimes recognized as a subspecies (not supported by DNA) under the name Zosterops pallidus sundevalli Hartlaub, 1865; see below under comments for details. STATUS REFERENCE: Dickinson & Christidis 2014: 520 and Bowie 2005: 823–824 (includes sundevalli Hartlaub, 1865 (see Gyldenstolpe 1926: 35, deserticola Reichenow, 1905 and haigamchabensis Bradfield, 1944). TYPE MATERIAL: We can find no indication in Sundevall’s original description text that he had more than a single specimen at hand, but according to his acquisition catalogue he apparently had three available. Gyldenstolpe (1926: 35) refers to NRM 568713 [6678] as a “type”; we treat this as a lectotype designation of this adult male collected 5 August 1843 north of the Vaal River. The two paralectotypes are: NRM 555448 [6679], a study skin of an adult female collected 5 August 1843 north of the Vaal River; and a specimen [6677] of unknown sex and only noted as “Caffr. Inf.” sent on exchange to Berlin in 1853 (but not found in the ZMB database). VERIFIED TYPE LOCALITY: North of Vaal River, North West Province. COMMENTS: Collected on the same day as the type of Alauda fasciolata (see above). The type locality is probably just south of Potchefstroom. Since this name was shown to be a homonym of Zosterops lateralis (Latham, 1801), a species from Australia and neighboring islands, Hartlaub created a substitute name, Zosterops sundevalli (Hartlaub 1865: 8–9). NRM 568713 is also the lectotype for Zosterops sundevalli. Zosterops pallidus Swainson, 1838, based on “Dr. Burchell’s Coll. No. 43”, collected on the north bank of the Orange River, about 16 km east of Prieska on 18 Sept 1811, has priority over both names. The type specimen is in the Oxford University Museum of Natural History., Published as part of Dean, W. Richard J., Åhlander, Erik & Johansson, Ulf S., 2022, Avian type localities and the type specimens collected by Johan August Wahlberg in southern Africa, pp. 521-560 in Zootaxa 5134 (4) on page 550, DOI: 10.11646/zootaxa.5134.4.3, http://zenodo.org/record/6541737, {"references":["Sundevall, C. J. (1850) Foglar fran sodra Afrika. Ofversigt af Kongliga Vetenskaps-akademiens forhandlingar, 7 (4), 96 - 111.","Dickinson, E. C. & Christidis, L. (2014) The Howard and Moore Complete Checklist of the Birds of the World. 4 th Edition. Vol. 2. Passerines. Aves Press, Eastbourne, 752 pp.","Hartlaub, G. (1865) Monographischer Versuch uber die Gattung Zosterops. Journal fur Ornithologie, 13 (73), 1 - 30. https: // doi. org / 10.1007 / BF 02261150","Bowie, R. C. K. (2005) Zosterops lateralis. In: Hockey, P. A. R., Dean, W. R. J. & Ryan, P. G. (Eds.), Roberts' Birds of Southern Africa, 7 th edition. John Voelcker Bird Book Fund, Cape Town, pp. 823 - 824.","Gyldenstolpe, N. (1926) Types of birds in the Royal Natural History Museum in Stockholm. Arkiv f or Zoologi, 19, 1 - 116."]}

A goal of the genomic era is to infer the evolutionary dynamics at play during the process of speciation by analysing the genomic landscape of divergence. However, empirical assessments of genomic landscapes under varying evolutionary scenarios are few, limiting the ability to achieve this goal. Here we combine RAD-sequencing and individual-based simulations to evaluate the genomic landscape in the silvereye (Zosterops lateralis). Using comparisons matched for divergence timeframe and gene flow context, we document how genomic patterns accumulate along the speciation continuum. In contrast to previous predictions, our results provide limited support for the idea that divergence accumulates around loci under divergent selection or that genomic islands widen with time. While a small number of genomic islands were found in populations diverging with and without gene flow, in few cases were SNPs putatively under selection tightly associated with genomic islands. Furthermore, we modelled the transition from localised to genome-wide levels of divergence using individual-based simulations that considered only neutral processes. Our results challenge the ubiquity of existing verbal models that explain the accumulation of genomic differences across the speciation continuum and instead support the idea that divergence both within and outside of genomic islands is important during the speciation process.DATA ACCESSION NUMBERSResequencing data from this study have been submitted to the National Center for Biotechnology Information (NCBI; https://www.ncbi.nlm.nih.gov) under accession number PRJNA489169.

When populations colonise new areas, both strong selection and strong drift can be experienced due to novel environments and small founding populations, respectively. Empirical studies have predominantly focused on the phenotype when assessing the role of selection, and limited neutral loci when assessing founder-induced loss of diversity. Consequently, the extent to which processes interact to influence evolutionary trajectories is difficult to assess. Genomic-level approaches provide the opportunity to simultaneously consider these processes. Here, we examine the roles of selection and drift in shaping genomic diversity and divergence in historically documented sequential island colonisations by the silvereye bird (Zosterops lateralis). We provide the first empirical demonstration of the rapid appearance of highly diverged genomic regions following population founding, the position of which are highly idiosyncratic. As these regions rarely contained loci putatively under selection, it is most likely that these differences arise via the stochastic nature of the founding process. However, selection is required to explain rapid evolution of larger body size in insular silvereyes. Reconciling our genomic data with these phenotypic patterns suggests there may be many genomic routes to the island phenotype, that vary across populations. Finally, we show that accelerated divergence associated with multiple founding steps is the product of genome-wide rather than localised differences, and that diversity erodes due to loss of rare alleles. However even multiple founder events do not result in divergence and diversity levels seen in evolutionary older subspecies, and therefore do not provide a shortcut to speciation as proposed by founder-effect speciation models.

Theory predicts that when populations are established by few individuals, random founder effects can facilitate rapid phenotypic divergence even in the absence of selective processes. However, empirical evidence from historically documented colonisations suggest that, in most cases, drift alone is not sufficient to explain the rate of morphological divergence. Here, using the human-mediated introduction of the silvereye (Zosterops lateralis) to French Polynesia, which represents a potentially extreme example of population founding, we reassess the potential for morphological shifts to arise via drift alone. Despite only 80 years of separation from their New Zealand ancestors, French Polynesian silvereyes displayed significant changes in body and bill size and shape, most of which could be accounted for by drift, without the need to invoke selection. However, signatures of selection at genes previously identified as candidates for bill size and body shape differences in a range of bird species, also suggests a role for selective processes in driving morphological shifts within this population. Twenty-four SNPs in our RAD-Seq dataset were also found to be strongly associated with phenotypic variation. Hence, even under population founding extremes, when it is difficult to reject drift as the sole mechanism based on rate tests of phenotypic shifts, the additional role of divergent natural selection in novel environments can be revealed at the level of the genome.

A new Isospora (Apicomplexa:Eimeriidae) species is described from a silvereye (Zosterops lateralis) in Western Australia. Sporulated oocysts of this species are spherical, 24.2 (23.1-25.2) × 23.3 (22.8-23.9) μm, with a shape index (length/width) of 1.02, and with a smooth bi-layered oocyst wall, 1.2 μm thick (outer layer 0.9 μm, inner 0.3 μm). A polar granule is present, but the oocyst residuum and a micropyle are absent. The ovoid-shaped sporocysts are 16.1 (15.7-17.3) × 10.5 (15.7-17.3) μm and have a shape index of 1.53. A hemidome-shaped Stieda and a rectangular-shaped substieda body are present. A sporocyst residuum is present and composed of numerous granules of different sizes scattered among the sporozoites. The oocysts from this isolate are morphologically different from those of all known Isospora spp. This coccidian parasite was molecularly characterised at the 18S, 28S ribosomal RNA and the mitochondrial cytochrome oxidase (COI) gene. At the 18S locus, based on 1210 bp of sequence, this new isolate exhibited 99.9, 99.8, 99.7 and 99.5% similarity to I. sp. MAH-2013a (KF648870) from a superb starling (Lamprotornis superbus) in Canada, I. sp. MS-2003 (AY33157) from a Southern cape sparrow (Plocepasser mahali) in America, I. sp. Tokyo (AB75786) from Japan and I. sp. respectively. Further analysis of a subgroup of 300 bp long 18S sequences (n = 11), including I. anthochaerae and the other three Isospora characterised from birds in Western Australia, revealed that I. butcherae n. sp. exhibited 98.3% similarity to both I. sp. MAH-2013a (KF648870) and I. MS-2003 (AY33171). At the 28S locus, this new isolate exhibited 97.3% similarity with I. sp. MS-2003 from a California towhee (Melozone crissalis). At the COI locus, this new isolate exhibited 99.8% similarity to I. neochmiae from a red-browed finch. Based on morphological and molecular data, this isolate is a new species of Isospora, which is named Isospora butcherae n. sp. after Mrs. June Butcher for her lifelong dedication as a wildlife rehabilitator. Graphical abstract ᅟ.

Wild bird feeding often results in high densities of birds, potentially facilitating transmission of disease. Wild birds are major reservoirs of many zoonotic diseases, and although a number of avian disease outbreaks have been linked to bird feeders, urban bird-feeding and its role in disease systems remains poorly studied. We examined the impacts of typical supplementary feeding practices on the health status of feeder-visiting birds at experimental feeding stations in an urban area of New Zealand. Over an 18-month period, we screened birds captured at feeding and non-feeding properties for three pathogens and four groups of parasites to determine whether feeding altered disease dynamics. We also assessed body condition. All pathogens and parasites were detected in at least one garden bird species. Feeding stations tested positive for Salmonella enterica Typhimurium on ∼7% of occasions, confirming that structures used in feeding are a potential transmission pathway. Feeding influenced some parasite infection parameters; these effects varied among host species. In silvereyes Zosterops lateralis, helminth prevalence and abundance were lower at feeding properties compared to non-feeding properties. In contrast, Eurasian blackbirds Turdus merula at feeding properties had a higher abundance of helminths. House sparrows Passer domesticus at feeding properties had a higher abundance of feather lice. Furthermore, our feeding regime significantly affected body condition in house sparrow and silvereye, though no associations between parasite parameters and body condition indices were found. Our results demonstrate that feeding practices can have varied effects on avian health, including no observable effects for some disease agents in some host species. Disease risks are present, however, thus understanding and reducing these risks should be a key goal for all stakeholders to protect birds that use feeders and other wildlife.

Among birds, white-eyes (genus Zosterops) have diversified so extensively that Jared Diamond and Ernst Mayr referred to them as the "great speciator." The Zosterops lineage exhibits some of the fastest rates of species diversification among vertebrates, and its members are the most prolific passerine island colonizers. We present a high-quality genome assembly for the silvereye (Zosterops lateralis), a white-eye species consisting of several subspecies distributed across multiple islands. We investigate the genetic basis of rapid diversification in white-eyes by conducting genomic analyses at varying taxonomic levels. First, we compare the silvereye genome with those of birds from different families and searched for genomic features that may be unique to Zosterops. Second, we compare the genomes of different species of white-eyes from Lifou island (South Pacific), using whole genome resequencing and restriction site associated DNA. Third, we contrast the genomes of two subspecies of silvereye that differ in plumage color. In accordance with theory, we show that white-eyes have high rates of substitutions, gene duplication, and positive selection relative to other birds. Below genus level, we find that genomic differentiation accumulates rapidly and reveals contrasting demographic histories between sympatric species on Lifou, indicative of past interspecific interactions. Finally, we highlight genes possibly involved in color polymorphism between the subspecies of silvereye. By providing the first whole-genome sequence resources for white-eyes and by conducting analyses at different taxonomic levels, we provide genomic evidence underpinning this extraordinary bird radiation.

In birds, song divergence often precedes and facilitates divergence of other traits. We assessed the relative roles of cultural drift, innovation, and acoustic adaptation in divergence of island bird dialects, using silvereyes (Zosterops lateralis). In recently colonized populations, syllable diversity was not significantly lower than source populations, shared syllables between populations decreased with increasing number of founder events, and dialect variation displayed contributions from both habitat features and drift. The breadth of multivariate space occupied by recently colonized Z. l. lateralis populations was comparable to evolutionarily old forms that have diverged over thousands to hundreds of thousands of years. In evolutionarily old subspecies, syllable diversity was comparable to the mainland and the amount of variation in syllable composition explained by habitat features increased by two- to threefold compared to recently colonized populations. Together these results suggest that cultural drift influences syllable repertoires in recently colonized populations, but innovation likely counters syllable loss from colonization. In evolutionarily older populations, the influence of acoustic adaptation increases, possibly favoring a high diversity of syllables. These results suggest that the relative importance of cultural drift and acoustic adaptation changes with time since colonization in island bird populations, highlighting the value of considering multiple mechanisms and timescale of divergence when investigating island song divergence.

Understanding the influence of environmental factors on population dynamics is fundamental to many areas in biology. Survival is a key factor of population biology, as it is thought to be the predominant driver of growth in long-lived passerines, which can be influenced by both biotic and abiotic environmental conditions. We used mark-recapture methods and generalized linear mixed models to test the influence of density and climatic variation, measured at a regional and local scale (Southern Oscillation Index [SOI] and rainfall, respectively), on seasonal variation in survival rates of an insular population of Silvereyes (Zosterops lateralis chlorocephalus), during a 15-year study period, off the east coast of Australia. We found overall high survival rates for adults and juveniles (81% and 59%, respectively). Local scale climate (i.e. rainfall) and density were the principal environmental factors influencing their survival, both with a negative relationship. A significant interactive effect of density and rainfall influenced survival as they both increased. However, survival remained low when density was at it highest, independent of the amount of rainfall. Nestling survival was negatively influenced by rainfall and density, positively by SOI, and chicks that hatched later in the breeding season had higher survival rates. The regional scale climate variable (i.e. SOI) did not explain survival rates as strongly as rainfall in any age class. Our results contribute to the understanding of insular avian population dynamics and the differential effects of environmental factors across age classes. Climatic predictions expect El Niño events to increase, meaning dryer conditions in eastern Australia, potentially increasing Silvereye survival across age classes. However, the long-term effect of lower rainfall on food availability is unknown; consequently, the outcome of lower rainfall on Silvereye survival rates is uncertain.

The Tapora Landcare Group, operating on the Okahukura Peninsula, has the long-term goal of making this region predator fenced. The aim of this study was to obtain information on the current status of avian biodiversity and the bird community across the band of coastal wetlands on the Okahukura Peninsula. Bird counts were conducted and playback lures used to detect three cryptic wetland species: fernbirds (Bowdleria punctata); spotless crakes (Porzana tabuensis); and banded rails (Gallirallus philippensis). Fernbirds and banded rails were detected at seven of the eight wetland sites sampled whereas spotless crakes were detected at two sites. The native species with the highest relative abundance across the eight sites were silvereyes (Zosterops lateralis) and South Island pied oystercatchers (Haematopus finschi). Changes in avian biodiversity over time in the region can now be monitored, and comprehensive long-term data on the status of avian biodiversity over time obtained.

Many passerines adjust song attributes to avoid potential masking by anthropogenic noise. The costs of masking should be particularly high for vocalizations important for survival (e.g. alarm calls), but few studies have investigated how such calls are affected. We compared urban and rural silvereye, Zosterops lateralis, alarm calls across southeastern Australia, and found that urban calls had lower average, peak and maximum frequencies than rural calls. The average, peak and maximum frequency of alarm calls also decreased linearly with increasing background noise. The direction of this frequency shift runs contrary to expectations and previous findings of higher-pitched avian vocal signals in urban habitats, including higher-pitched song and contact calls in urban silvereyes. However, assuming no change in call amplitude, acoustic modelling indicates that the observed frequency shift would lead to a 20% increase in the predicted active space of alarm calls (i.e. the distance over which the calls can be detected by a conspecific bird) in urban noise, and therefore may be potentially adaptive. Our findings highlight the importance of considering behavioural and ecological contexts in urban acoustic-adaptation studies.

Whereas the changes in avian community composition resulting from urban development are well described, the specific factors that allow certain species to thrive in urban areas remain poorly understood. However, the availability of arthropod prey is emerging as a potentially important factor in shaping urban bird communities. Silvereyes (Zosterops lateralis) are common in urban areas and so provide a useful study organism to test the factors that allow some birds to become urban ‘winners’. We here present the results of an observational study on the foraging frequency of Silvereyes and arthropod prey availability in native and exotic urban trees in Dunedin, New Zealand. Silvereyes more frequently used individual trees, native or exotic, that supported the highest level of arthropod abundance. Silvereye foraging also varied greatly on a seasonal scale. Silvereyes were able to adjust their seasonal foraging to incorporate exotic vegetation with high arthropod abundances. We conclude that the flexibility of Silvereyes with regards to foraging and their use of exotic plant species are important factors in their success in surviving urban development.

Differences in song repertoires and characteristics of island and mainland populations of the same avian species are usually explained by dispersal, cultural evolution and/or habitat differences. The influence of morphology is often overlooked, even though island populations are frequently morphologically distinct from mainland populations, and morphology could affect vocalizations. I compared morphological features, songs, contact calls and alarm calls of six isolated island populations of silvereye Zosterops lateralis with those of two mainland populations to examine whether differences between mainland and island vocalizations were consistent across vocalization types, and whether these differences could be linked to morphological differences. Vocalizations were lower in frequency on islands. Island individuals were larger (both in mass and body structure), and body mass was an important predictor of frequency in contact and alarm calls. I argue that this strong association results from the island rule (islands promote larger body sizes) and cascading effects of morphology on vocalization frequency in this species.

Many birds raise the pitch of their vocalizations in urban environments, a shift generally attributed to avoidance of low frequencies vulnerable to masking by anthropogenic noise (acoustic adaptation hypothesis [AAH]). However, high frequencies could just be an incidental byproduct of singing more loudly (Lombard hypothesis). If birds cope with background noise by singing more loudly and increases in frequency are byproducts of increased amplitudes, they should respond with louder songs (and increased pitch) to either high- (HFN) or low-frequency noise (LFN) of similar amplitude. However, if birds adaptively adjust frequency to minimize interference, they should increase frequency in response to LFN but decrease it in response to HFN. We exposed silvereyes (Zosterops lateralis), which use higher songs and calls in urban areas, to high- and low-frequency background noise of standardized amplitude. Silvereyes from both rural and urban areas exposed to HFN responded by lowering the minimum frequencies of their calls, and this shift was independent of call amplitude, which increased in all noise treatments. These findings support the AAH. Calls during HFN treatments were also longer than those made during quiet treatments. Our results suggest that silvereyes are capable of flexible adjustments of call frequency, amplitude, and duration to maximize signal-to-noise ratio in noisy environments.

Most birds have a uropygial gland, which produces preen wax that birds spread over their feathers when preening. Preen waxes contain a variety of volatile components which may function, in some species, as signals to communicate identity of mates and nest sites, or provide information about the owner’s state. Such signals may not be reliable if preen wax composition is readily altered by changes in diet. We used a diet supplementation experiment in a New Zealand population of silvereyes, Zosterops lateralis, to determine if preen wax composition varied with diet. During the austral breeding season, free-living silvereyes were fed a mix of animal tallow ad libitum for a period of 22 days. Their preen waxes were collected 6 and 7 days (sampling period 1), 11 days (sampling period 2), and 21 and 22 days (sampling period 3) after the beginning of the diet supplementation to determine if preen wax composition would change in response to the addition of the supplemental food. Birds sampled within a 7-day period leading up to the diet supplementation acted as controls. We found no significant changes in the preen wax throughout the study period. Feeding did not affect preen wax composition, and there was no change in preen wax composition among sampling periods. Date of sampling also did not affect preen wax composition during the period of the experiment. As the preen wax of silvereyes is known to change between non-breeding and breeding seasons, the lack of change in our study was not simply the result of preen wax production being fixed. Instead, our results support the hypothesis that preen wax composition in silvereyes is determined by endogenous mechanisms and is not affected by day-to-day variation in diet.

Members of the genus Zosterops are known for their colonizing ability and extensive phenotypic differentiation on numerous islands. There have been morphological and biochemical analyses of some Zosterops populations, but little study has been devoted to patterns of vocal communication signals, known to be important pre-mating barriers in many bird species and in possible diversification of taxa. I report on the song system of one subspecies of Zosterops in a mainland population and an island population 15 km distant. I used both a traditional subjective classification of song elements and the multivariate procedure of linear discriminant analyses (LDA) of measured sound features. The syllables constituting songs exhibited a low level of stereotypy, disallowing a lexicon of syllable ‘types’ to be constructed for individuals or a population. New syllables were continuously produced as a bird uttered more and more songs, possibly indicating an extremely large repertoire or an open-ended generation ...

The bioacoustic attributes of vocalisations made by birds in urban environments often differ markedly from those of rural conspecifics. Whether such differences are result from genetic divergence between urban and rural populations, or from plasticity or cultural evolution of song remains poorly understood. Silvereyes (Zosterops lateralis) show evidence of acoustic adaptation to urban noise, modifying both their songs and calls in cities when compared to rural areas. We investigated whether these differences were associated with corresponding morphological and neutral genetic differences. Across six pairs of geographically separate urban and rural populations, all morphological traits measured were similar. Furthermore, genetic analyses of variation at nine microsatellite loci revealed high levels of genetic connectivity between populations, and similar levels of heterozygosity in both habitat types. Consistent directional shifts in song attributes of city birds across large geographic areas thus do not appear to be accompanied by associated morphological or neutral genetic divergence.

The loss of bird species following human colonization of New Zealand has raised concerns about the consequences for crucial ecosystem functions such as pollination. The understorey shrub Alseuosmia macrophylla (Alseuosmiaceae) exhibits characteristics typical of a bird pollination syndrome, but populations still persist in northern North Island forest remnants despite the local extinction of most endemic bird pollinators, leading to the suggestion that moths – rather than birds – may be the primary pollinators. The aim of this study was to quantify the importance of endemic birds as pollinators of A. macrophylla over several years by comparing plants on Little Barrier Island (LBI), where all extant endemic bird pollinators still occur, to plants at sites on the adjacent North Island in the Waitakere Ranges (WTK), where only one of these species remains common. Flowers on LBI were visited by endemic bellbirds (Anthornis melanura) and stitchbirds (Notiomystis cincta), while at WTK sites the most common visitors were the recently arrived silvereye (Zosterops lateralis) and the introduced honeybee (Apis mellifera), both of which acted principally as nectar robbers. Caged flowers on LBI had significantly lower fruit set than open flowers, and plants at WTK were significantly more pollen-limited than plants on LBI. This provides evidence that the loss of endemic pollinating birds is the most likely reason for the high pollen limitation found in some North Island A. macrophylla populations, and the very low seed set of these populations could have serious implications for the long-term persistence of this species.

Predation of eggs and/or chicks is the main cause of nesting failure in birds. Nest predation has been studied in many habitats in New Zealand, but few studies have been conducted in urban ecosystems. Twenty-one nests of four bird species (blackbird [Turdus merula], song thrush [Turdus philomelos], fantail [Rhipidura fuliginosa], and silvereye [Zosterops lateralis]) were monitored over one breeding season in Hamilton using time-lapse recordings. Five predation events were filmed (two by cats [Felis catus], and three by ship rats [Rattus rattus]), 10 nests successfully fledged chicks and 6 nests failed owing to poor weather, desertion, or unknown events. Although the sample size was small, our data suggest that nesting success may be higher in urban Hamilton than in other unmanaged habitats where predation rates can exceed 80%. We recommend that future studies of nesting success in urban birds should also focus on the fates of fledglings, as anecdotal evidence suggested that predation rates may ha...

We compared the feeding behaviour of garden birds in the presence of four heterospecific decoy species at suburban feeding stations to assess the relative importance of body size (large vs. small) and demeanour (high vs. low potential for inter-specific aggression) as cues for threat recognition. We conducted separate trials with live, caged Australian magpie, Cracticus tibicen, and common myna, Acridotheres tristis, large and small species known to chase and harass heterospecifics, and comparably sized species not known for inter-species aggression (i.e. rock dove, Columba livia, and ringneck dove, Streptopelia risoria). Birds of all species arrived at feeding stations sooner and displayed higher-risk activities in the presence of small decoys. The two most common species that visited the feeding stations, silvereye, Zosterops lateralis, and house sparrow, Passer domesticus, were most likely to perform high-risk behaviours (i.e. landing on the stimulus cage and feeding from the station) in the presence of common mynas. The activities were performed least frequently in the presence of Australian magpies. As garden birds likely had the most experience interacting with common mynas, the results suggest that a two-step decision rule, with size and familiarity as important cues, may be used to recognize potential threats.

Secondary metabolites in fruit are compounds that are not directly associated with plant growth; some are directly related to plant reproductive processes, specifically seed protection and dispersion. There is a complex and species-specific interaction between these plant compounds and their avian seed dispersers. To determine whether two important secondary metabolites in wine grapes – tannins and colour pigments – might be important cues to two of the avian species that forage on wine grapes, and how species-specific this interaction might be, comparative field experiments were run with Australasian silvereyes (Zosterops lateralis) and European blackbirds (Turdus merula). Both species were offered a glucose/fructose artificial nectar with increasing concentrations of grape tannins. In a second experiment, they were offered both green and purple artificial grapes where only the colour differed. Both species showed aversion to tannins; silvereyes appeared to have greater tolerance than blackbirds of tannin concentrations above 5%. In summer no preference was shown between green and purple coloured artificial grapes, but in late autumn blackbirds took only purple grapes whereas silvereyes pecked mostly at green. Links between tannin for seed protection and colour signals to birds are discussed. Colour may cue the two species to different species-specific aspects of fruit nutritive value.

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. 1994 Blackwell Verlag GmbH

Incubation can be as energetically costly as rearing chicks(Williams 1991, Tatner & Bryant 1993, Thomson et al.1998a) and might even limit clutch size (Heaney M Thomson et al. 1998b).In Semipalmated Sandpipers Calidris pusilla, anotherbiparental incubator, parents increased incubation by10% when heat loss from eggs was reduced by insulat-ing the nest (Cresswell et al. 2003). These results weresimilar to those for uniparental incubators (Thomsonet al. 1998a, Bryan & Bryant 1999), suggesting biparen-tal incubating species might be as constrained byenergy availability as uniparental incubators. However,few data exist on the incubation strategies of biparen-tal incubating passerines in response to changes in foodavailability.In this study, we assessed the effect of food supple-mentation on incubation behaviour of the biparentalSilvereye Zosterops lateralis. We provided a food supple-ment to free-living Silvereyes and compared the incuba-tion attentiveness of adults before and after they weresupplemented. Many studies show that food supplemen-tation can increase attentiveness (e.g. Nilsson & Smith1988, Eikenaar et al. 2003, Gorman & Nager 2003,Pearse et al. 2004, Chalfoun & Martin 2007, but seeMoreno 1989, Mackintosh & Briskie 2005), but fewhave determined how individual incubation behaviourchanges in response to short-term food supplementation.We used a repeated-measures approach in which incuba-tion behaviour of individual birds was compared beforeand after they received supplementary food. Our resultsshow that Silvereyes increased their attentiveness andother measures of incubation investment in response tofood supplementation.METHODSStudy site and subjectsThe study was conducted during spring 2000 and 2001 atthe Kowhai Bush Reserve (173 36 ¢E, 42 23 S)near Kaikoura, New Zealand. The Silvereye is a small(11–14 g) passerine that ranges throughout Australia andthe South Pacific. The species is insectivorous, but con-sumes nectar and fruit when available. Sexes are similarin size and colouration and both males and females incu-bate, brood and feed nestlings (Heather & Robertson1996). Nests are spaced 10–30 m apart but adults arenon-territorial and only defend an area c. 1 m around thenest. Females alone build a well-concealed cup nest in thelower canopy in which they lay two to four eggs. Incuba-tion begins once the clutch is complete and nestlingshatch about 11 days later (Heather & Robertson 1996).We measured changes in incubation behaviour withfood supplementation at 10 nests. To avoid pseudorepli-cation, we only sampled nests once and did not samplenests of individuals used in previous experiments. Obser-vations of colour-ringed Silvereyes indicate that theyre-nest near previous breeding attempts and thus we didnot use any nest found in the same general area( 50 m) as a previously studied nest.

Winter survival with respect to dominance classes of 932 individually colour‐ringed Silvereyes was examined on Heron Island, Great Barrier Reef, between 1965 and 1969. The dominants (winning two‐thirds or more of aggressive encounters) had significantly better chances of survival between May and August (southern winter) than other birds. The 1967/68 year group was studied in detail; the young born early in the breeding season contained proportionately more dominants than those born later in the season and dominant birds tended to survive better in winter. Adults in the same period showed no dominance dependent survival. The weight of birds in winter differed between first‐year birds and adults in most cases, but winter mortality within each year‐group was not related to the weight of individual birds in May. However, the dominant class had a smaller proportion of birds losing weight through the winter than other classes, and the dominant adults and the intermediate class of first‐year birds tended to be heavier than others in August. The lengths of wing, tail, tarsus and exposed culmen examined for the 1967/68 year group showed no significant trends in either survival or dominance classes. Better survival of dominant birds is considered to be a consequence of their feeding advantages over others, but the intensity of selection for an ability for dominance may fluctuate from year to year in relation to the population density and distribution and abundance of food supply.

Age-related differences in foraging efficiency and behaviour were investigated in a population of colour-ringed Silvereyes Zosterops lateralis. First-year birds were less efficient foragers than older birds with second-year birds being intermediate. First- and second-year birds had lower success rates than older birds overall, and for most capture techniques and substrates. First-year birds never attempted breeding while about half of the second-year birds and all of the older birds did. Both learning and selection effects may have been involved in causing the age-related differences in foraging behaviour. Foraging skills appear to improve during the first 2 years of life and selection could remove the least efficient foragers from the population in winter when food is short. That second-year birds, some of which had already attempted breeding, were not significantly more efficient foragers than first-year birds suggests that reproduction is not delayed until adult levels of foraging efficiency have been attained.

Summary 1. In 1959 and 1960 observations on winter flocks of the White-eye Zosterops lateralis were made at a feeding station and in an aviary at Dunedin, New Zealand. 2. Aggressive behaviour takes different patterns according to the intensity of aggression; ritualized pecking, threat display, incipient attack, combat and chasing are distinguished. Many components of the basic threat posture are similar to those of other passerine species, but “wing fluttering”, presentation of white underwing coverts and the brown colour on the flank, and “beak clattering” seem to be characteristic of the White-eye. “Wing fluttering” is an incipient attack and often develops into an actual attack when stimulated by identical posturing by an opponent. 3. The pecking order found in the captive birds was a peck-right hierarchy, but triangular relations were also observed when mated birds were involved. Prior residence was effective for a short period only and the despot in the prior occupants could be defeated by an aggressive intruder. 4. 710 birds were colour-ringed at the feeding station, 306 returned and 204 were observed in aggressive encounters. The analysis of these encounters showed that in natural flocks dominant birds are engaged in aggressive encounters more frequently than subordinate birds, that dominants fight more often with birds of higher ranks, and that subordinates avoid encounters with aggressive birds. 5. A complex peck-right hierarchy was found among members of different flocks visiting the feeding station. It is suggested that aggressive behaviour serves to establish and maintain the social hierarchy among individuals coming into contact over various objects. In crowded conditions severe fighting frequently takes place and the right of prior residence may be challenged constantly. 6. The importance of ecological implications of flocking and aggressive behaviour in the White-eye population in New Zealand is discussed.

We examined the relationships between food resources, territory density and some breeding parameters (individual reproductive success and parental age) of a Capricorn Silvereye population during two years' detailed study on Heron Island, Great Barrier Reef. The territorial behaviour of the Silvereyes included dawn song. aggression and distinctive vocalizations. During both years, about 85% of pairs occupied territories although the population sizes differed. The dispersion pattern of territories was not regular and was correlated with the density of figs and human food scraps. Nestlings were fed more figs as they grew, and the parents foraged in fig trees outside their territories. However, only about 60%, of territorial pairs fledged young. Pairs which fledged most young were older, fed more insects to their nestlings, and nested in areas containing more fruiting fig trees per territory. We conclude that food resources were in short supply, and that access to fig trees provided breeding birds with a quick energy source while they searched for insect protein for the young. The data are consistent with the predictions of the ‘sufficient resource‘ hypothesis of the adaptive significance of territoriality but not with its assumption that the principal benefit is the food within the territory. Copyright

The 558 prey items brought home by one domestic cat, recorded over its 17‐year lifetime, included 221 mice, 63 rats, 35 rabbits, 4 hares and 2 weasels. The cat hunted up to 600 m from the house, and prey was caught both inside and outside the 0.5 ha garden. Of the 223 birds brought in, 54 were native, including 43 silvereyes (Zosterops lateralis), but those killed were quickly replaced, so there was always a resident population of 1–2 pairs. The other known native birds comprised five fantails (Rhipidura fuliginosa), four warblers (Gerygone igata), a kingfisher (Halcyon sancta), and a shining cuckoo (Chrysococcyx lucidus). Only nine skinks (Cyclodina aenea) and one frog (Litoria raniformis) were brought in. The abundance of birds and reptiles in the garden showed no apparent change over the 17 years compared with the previous 15‐year‐period without a cat. By contrast, the cat exterminated the rabbit population in the garden, and “farmed” surrounding burrows during its whole life; all other prey k...