Japanese White-eye Research Articles

최근 10년(2013-2022년)간 다도해해상국립공원 흑산도의 조류 도래 현황

In Heuksan Island in Dadohaehaesang National Park in the southwest of the Korean Peninsula, we studied to find out the current status of bird banding for 10 years from 2013 to 2022, the minimum period of stay, and the minimum life expectancy in the stopover sites by species. We catched to a total of 56,778 of 194 species, and 98.4% of Passeriformes. The proportion of males was high with 25.0% for females and 28.0% for males, 48.6% for young birds and 32.4% for adult birds. 6.7% of all were re-captured in the same area, followed by 24% of the Zosterops japonicus, 15% of the Emberiza spodocephala, and 8% of the Parus minor and Turdus pallidus. There was a difference in the minimum length of stay between species in the Emberizidae, Emberiza pallasi stayed 1.8 days (n=222) and of the Emberiza pusilla stayed 8.6 days (n=52).

Linking avian malaria parasitemia estimates from quantitative PCR and microscopy reveals new infection patterns in Hawai'i

Plasmodium parasites infect thousands of species and provide an exceptional system for studying host-pathogen dynamics, especially for multi-host pathogens. However, understanding these interactions requires an accurate assay of infection. Assessing Plasmodium infections using microscopy on blood smears often misses infections with low parasitemias (the fractions of cells infected), and biases in malaria prevalence estimates will differ among hosts that differ in mean parasitemias. We examined Plasmodium relictum infection and parasitemia using both microscopy of blood smears and quantitative polymerase chain reaction (qPCR) on 299 samples from multiple bird species in Hawai'i and fit models to predict parasitemias from qPCR cycle threshold (Ct) values. We used these models to quantify the extent to which microscopy underestimated infection prevalence and to more accurately estimate infection patterns for each species for a large historical study done by microscopy. We found that most qPCR-positive wild-caught birds in Hawaii had low parasitemias (Ct scores ≥35), which were rarely detected by microscopy. The fraction of infections missed by microscopy differed substantially among eight species due to differences in species’ parasitemia levels. Infection prevalence was likely 4–5-fold higher than previous microscopy estimates for three introduced species, including Zosterops japonicus, Hawaii’s most abundant forest bird, which had low average parasitemias. In contrast, prevalence was likely only 1.5–2.3-fold higher than previous estimates for Himatione sanguinea and Chlorodrepanis virens, two native species with high average parasitemias. Our results indicate that relative patterns of infection among species differ substantially from those observed in previous microscopy studies, and that differences depend on variation in parasitemias among species. Although microscopy of blood smears is useful for estimating the frequency of different Plasmodium stages and host attributes, more sensitive quantitative methods, including qPCR, are needed to accurately estimate and compare infection prevalence among host species.

Do nocturnal birds use acoustic and visual cues to avoid predation by bats?

Anti-predation strategies are critical to animal survival and are fundamental to deciphering predator-prey interactions. As an important defense strategy, sensory predator detection (such as through acoustic and visual cues) enables animals to assess predation risk and execute predator-avoidance behavior; however, there are limited studies on the anti-predation behavior of nocturnal animals. The prey of bats provides an excellent representative system for examining the anti-predation behavior of nocturnal animals. Here, we broadcasted different types of echolocation calls of the bird-eating bat Ia io to two wild passerine birds, namely, Zosterops japonicus and Sinosuthora webbiana, that are preyed upon by I. io, and presented the birds with individual bats under different light intensities. The results showed that both bird species were able to perceive the low-frequency audible portion of the bats' echolocation calls; however, they did not exhibit escape responses to the acoustic stimuli. In the dark and under moonlit conditions, both bird species were unable to respond to active bats at close range and the birds only exhibited evasive flight behavior when bats approached or touched them. These results suggest that nocturnal passerine birds may not be able to use acoustic or visual cues to detect bats and adopt evasive maneuvers to avoid predation. This work suggests that bat predation pressure may not elicit primary predator-avoidance responses in nocturnal passerine birds. The results provide new insights into the anti-predation behavior of nocturnal animals.

Nectar microbes may indirectly change fruit consumption by seed-dispersing birds

An increasing number of recent studies show that nectar-inhabiting microorganisms influence plant fitness by mediating interactions between plants and pollinators. However, whether the effects of nectar microbes extend beyond pollination to affect subsequent stages of plant reproduction remains largely unknown. This study aims to explore whether nectar microbes can indirectly affect fruit consumption by birds, which can be essential for seed dispersal and germination. Wild flowers of Eurya japonica trees were experimentally inoculated with the nectar-inhabiting yeast Metschnikowia reukaufii and the nectar-inhabiting bacterium Acinetobacter boissieri, both of which had been previously isolated frequently from E. japonica flowers. In this experiment, I examined whether these microbes changed female reproductive success of the understory tree. Experimental inoculation of flowers with yeasts decreased fruit and seed set compared to those inoculated with bacteria, and the control. Furthermore, fruits with higher seed set tended to be larger, and larger fruits were more likely to be consumed by seed-dispersing birds, including the Japanese white-eye Zosterops japonica, the brown-eared bulbul Hypsipetes amaurotis, and the Daurian redstart Phoenicurus auroreus. These results suggest that nectar-inhabiting microorganisms have the potential to affect plant reproduction by influencing not only plant-pollinator interactions, but also by indirectly modifying plant-frugivore interactions via changes in plant-pollinator interactions.

Issue Information

A Orobanche boninsimae and its visitors, Japanese white‐eyes (Zosterops japonicus). Photo by Akihiro Nishimura at Chichijima Island, the Bonin Islands, Japan. Nishimura & Takayama (2023) “First record of potential bird pollination in the holoparasitic genus Orobanche L.” Plant Species Biology, 6–17 https://doi.org/10.1111/1442-1984.12389image

Opportunistic depredation of songbird nestlings by female praying mantids (Mantodea: Mantidae).

Praying mantids (class Insecta, order Mantodea) are a group of predatory insects comprising approximately 2500 described species, that occur across all continents except Antarctica, with the greatest species diversity in tropical and subtropical regions. Mantids predominantly prey on other invertebrates but are known to feed on small vertebrates. During April and May 2021, we observed mantid feeding events in Manujan County, Kerman Province in southern Iran. Two distinct feeding events were observed where female European Mantids (Mantis religiosa) preyed on Purple Sunbird (Cinnyris asiaticus) and Crested Lark (Galerida cristata) nestlings. In addition, we collated information from online searches of mantids feeding on nestlings elsewhere in the world, revealing two more observations. In Taiwan, a Giant Asian Mantid (Hierodula patellifera) was recorded preying on a nestling Warbling White-eye (Zosterops japonicus) and in Brazil, a mantid (Stagmatoptera sp.) was recorded feeding on a nestling White-throated Seedeater (Sporophila albogularis). To date, the only existing scientific evidence of praying mantids feeding on passerine nestlings was recorded in 1922. We propose two potential explanations for the observed trophic interactions between mantids and passerine nestlings: (1) during egg production female mantids, especially those in poor physical condition, may opportunistically feed on nestlings in order to increase fecundity via nutrient gain and (2) mantids may initially be attracted toward the nest by parasitic or coprophagous insects, as a result of poor nest sanitation, and subsequently prey on nestlings after detecting movements. Our unusual observations represent the first records of praying mantids feeding on nestling passerines in nearly 100 years.

Microbiomes associated with avian malaria survival differ between susceptible Hawaiian honeycreepers and sympatric malaria-resistant introduced birds.

Of the estimated 55 Hawaiian honeycreepers (subfamily Carduelinae) only 17 species remain, nine of which the International Union for Conservation of Nature considers endangered. Among the most pressing threats to honeycreeper survival is avian malaria, caused by the introduced blood parasite Plasmodium relictum, which is increasing in distribution in Hawai'i as a result of climate change. Preventing further honeycreeper decline will require innovative conservation strategies that confront malaria from multiple angles. Research on mammals has revealed strong connections between gut microbiome composition and malaria susceptibility, illuminating a potential novel approach to malaria control through the manipulation of gut microbiota. One honeycreeper species, Hawai'i 'amakihi (Chlorodrepanis virens), persists in areas of high malaria prevalence, indicating they have acquired some level of immunity. To investigate if avian host-specific microbes may be associated with malaria survival, we characterized cloacal microbiomes and malaria infection for 174 'amakihi and 172 malaria-resistant warbling white-eyes (Zosterops japonicus) from Hawai'i Island using 16S rRNA gene metabarcoding and quantitative polymerase chain reaction. Neither microbial alpha nor beta diversity covaried with infection, but 149 microbes showed positive associations with malaria survivors. Among these were Escherichia and Lactobacillus spp., which appear to mitigate malaria severity in mammalian hosts, revealing promising candidates for future probiotic research for augmenting malaria immunity in sensitive endangered species.

First record of potential bird pollination in the holoparasitic genus Orobanche L.

AbstractPollinators play an important role in the reproduction of zoophilous plants. A shift in pollinators has often been observed for oceanic island plants, probably because of the differences in fauna. In this study, we obtained data on pollinator shifts from insects to birds in Orobanche boninsimae (Orobanchaceae), a holoparasitic plant species endemic to the Bonin (Ogasawara) Islands, oceanic islands in the Pacific. We observed pollination and measured seed viability in O. boninsimae and its continental sister species O. coerulescens. We found that two passerine birds, the Japanese white‐eye (Zosterops japonicus) and bulbul (Hypsipetes amaurotis squameiceps), visited the flowers and sucked the nectar of O. boninsimae, while only insects visited those of O. coerulescens. Viable seeds were produced under pollinator‐excluded treatments in the two Orobanche species, indicating that the seeds were produced by automatic self‐pollination and/or apomixis. These results suggest that O. boninsimae may be pollinated by birds and can produce seeds by automatic self‐pollination/apomixis. This is the first record of visitation of the genus Orobanche by birds. Studies of pollination systems in native plants on the Bonin Islands are few compared to those on other oceanic islands, and O. boninsimae may provide a valuable example of pollinator shifts in the Bonin Islands.

Exploration of aversive bioacoustics for the effective management of invasive green anoles (Anolis carolinensis)

The green anole (Anolis carolinensis) is an invasive lizard on the Ogasawara Islands, Japan. Green anoles have negatively impacted the native fauna, and thus, green anole eradication measures, such as the use of PTFE-sheet fencing to restrict their movement have been implemented. However, the effectiveness of fencing appears inadequate; therefore, new methods are needed to deter this species. In this study, we explored the use of aversive bioacoustics by testing whether green anoles froze or stayed away on being exposed to predatory sounds and heterospecific alarm calls. Green anoles showed longer freezing times on hearing bird calls than on hearing no sound or single tones. In addition, they stayed far from the audio sources playing the calls of the red-tailed hawk (Buteo jamaicensis) and alarm calls of the warbling white-eye (Zosterops japonicus). Our results suggest that green anoles avoid certain bioacoustics, especially the calls of B. jamaicensis and the alarm call of Z. japonicus. Hence, these bioacoustics can be used as an effective control method to restrict the invasion and dispersion of green anoles.

Specific interactions in seed dispersal by the Japanese white‐eye Zosterops japonicus: Factors influencing its preference for two plant species, Aralia elata and Zanthoxylum ailanthoides

AbstractMany frugivorous birds act as seed dispersers for freshly fruited plants. Typically, one bird species has multiple plant partners, functioning as a generalist disperser. However, specific interactions also can be formed, depending on the traits of birds and plants. Our field observation from 2017 to 2019 suggested that Zosterops japonicus as frugivore prefers the fruits of Aralia elata and Zanthoxylum ailanthoides, thus dispersing the seeds locally in central Japan. In this study, we examined the factors of the preference by comparing the morphological traits among plants and observing foraging efficiency on each plant. The tree traits of the two plants were characterized by large crop size and high number of fruits that Z. japonicus can forage on a certain point of a branch (NFZ). Their fruits were also characterized by small size and high share of lipids in the edible parts. The traits of edible parts differed between the two plants; A. elata fruits had succulent pulps, whereas Z. ailanthoides fruits only contained oil composed of oleic aids. Additionally, the number of fruits per second consumed by Z. japonicus was significantly higher in the two plants than those in other plants. The foraging efficiency was enhanced by large crop size, large NFZ, small fruit size, and high lipid content of fruits. The high foraging efficiency may increase the preference of Z. japonicus for the two plants, leading to the specific interactions.

Estimation of reaction time for birdsongs and effects of background noise and listener’s age

Recordings of birdsong are often used as an auditory signal for visually-challenged people in public spaces in Japan. To examine the detectability of these sounds, we measured reaction times (RTs) for six types of birdsong: Jay, Cuckoo, Himalayan cuckoo, Japanese grosbeak, Japanese white-eye, and Japanese bush warbler. We presented birdsong stimuli with irregular timing to 20 younger and 20 older participants in combination with silence, white noise, or bandpass noise with a center frequency of 1, 2, or 4 kHz. Regardless of the output levels and participant age, the RT for the Jay, Cuckoo, and Himalayan cuckoo songs was lower than 0.75 sec in the silent condition, and the averaged RT obtained by the younger participants could be estimated on the basis of the duration required to reach a specified sound exposure level for the birdsong stimuli. In the noisy conditions, spectral masking via bandpass noise prolonged the RT, while the bandpass noise with a center frequency higher than that of the birdsong tended to shorten the RT, especially in older participants.

Long-term dynamics of the network structures in seed dispersal associated with fluctuations in bird migration and fruit abundance patterns.

In temperate zones, seed-dispersal networks by migratory birds are formed on long time scale. In mid-October from 2005 to 2016, to explore the dynamics of the network structures, we examined interannual variability of fruit abundance, bird migration, and seed-dispersal networks in central Japan. For 12years, the fruit abundance exhibited a remarkable fluctuation across years, with the number of fruiting plants and matured fruits fluctuating repeatedly every other year, leading to the periodic fluctuations. The abundance of migratory birds was also fluctuated. According to the abundance of fruits and migratory birds, the 12years was classified into three types: frugivores and fruits were abundant, frugivores were abundant but fruits were scarce, and frugivores were scarce. The seed-dispersal networks were investigated by collecting faeces and vomits of migrants. Of the 6652 samples collected from 15 bird species, 1671 (25.1%) included seeds from 60 plant species. Main dispersers were composed of Turdus pallidus, T. obscurus, and Zosterops japonicus. The network structures were almost nested for 12years. Specifically, the nested structure was developed in years when fruit abundance was low. GLM analyses showed the abundance of migrants, particularly T. pallidus and T. obscurus, had strong positive effects on nested structure. It may be caused by the fact the two Turdus species were more frequently functioning as generalist dispersers when fruit abundance was lower. Our study suggested fruit abundance and foraging behaviour of frugivores determine the network structures of seed dispersal on long time scale.

Identification of novel bacterial biomarkers to detect bird scavenging by invasive rats.

Rapid advances in genomic tools for use in ecological contexts and non‐model systems allow unprecedented insight into interactions that occur beyond direct observation. We developed an approach that couples microbial forensics with molecular dietary analysis to identify species interactions and scavenging by invasive rats on native and introduced birds in Hawaii. First, we characterized bacterial signatures of bird carcass decay by conducting 16S rRNA high‐throughput sequencing on chicken (Gallus gallus domesticus) tissues collected over an 11‐day decomposition study in natural Hawaiian habitats. Second, we determined if field‐collected invasive black rats (Rattus rattus; n = 51, stomach and fecal samples) had consumed birds using molecular diet analysis with two independent PCR assays (mitochondrial Cytochrome Oxidase I and Cytochrome b genes) and Sanger sequencing. Third, we characterized the gut microbiome of the same rats using 16S rRNA high‐throughput sequencing and identified 15 bacterial taxa that were (a) detected only in rats that consumed birds (n = 20/51) and (b) were indicative of decaying tissue in the chicken decomposition experiment. We found that 18% of rats (n = 9/51) likely consumed birds as carrion by the presence of bacterial biomarkers of decayed tissue in their gut microbiome. One species of native bird (Myadestes obscurus) and three introduced bird species (Lophura leucomelanos, Meleagris gallopavo, Zosterops japonicus) were detected in the rats’ diets, with individuals from these species (except L. nycthemera) likely consumed through scavenging. Bacterial biomarkers of bird carcass decay can persist through rat digestion and may serve as biomarkers of scavenging. Our approach can be used to reveal trophic interactions that are challenging to measure through direct observation.

Cordia subcordata (Boraginaceae), a distylous species on oceanic coral islands, is self-compatible and pollinated by a passerine bird

Background and aims – Distyly is usually rare on oceanic islands, which is probably due to the difficulty for distylous plants to colonize those islands. However, Cordia subcordata was observed to be distylous with short- and long-styled morphs on the Xisha Islands in the South China Sea. To characterize the reproduction system of Cordia subcordata and to understand how this distylous species maintains itself on these islands, we studied its reproductive and pollination biology.Methods – Seed set and pollen tube growth under manipulated intermorph, intramorph, and self-pollination were examined to investigate self-incompatibility in the species. The number of pollen grains deposited on the stigmas after a single pollinator visit were counted to investigate the pollination efficiency of different visitors. Key results – Our study indicated that Cordia subcordata shows reciprocal herkogamy as is typical in distylous species. Pollen tubes could reach the base of the style and move into the ovules under all the manipulated pollination treatments in both morphs. Seed set resulting from four hand-pollination experiments did not show any differences between both morphs, suggesting that Cordia subcordata lacks heterostylous self-incompatibility. The most frequent flower visitors, Zosterops japonicus and Apis cerana, were observed foraging on the large volumes of nectar and pollen grains, respectively, with Zosterops japonicus being the most effective pollinator, depositing large number of pollen grains on the stigmas during their visits.Conclusions – Our findings show that Cordia subcordata established itself and persists in the archipelago by producing fruits through a combination of self-compatibility and pollination by the most common passerine bird on the oceanic islands.

Bird-Banding Records Reveal Changes in Avian Spring and Autumn Migration Timing in a Coastal Forest Near Niigata

Changes in the timing of bird migration in spring and autumn in a coastal forest near the city of Niigata, central Honshu, Japan, were analyzed based on 27 years of bird-banding records. Half of the bird species studied, including all migratory types except residents, arrived or departed significantly earlier in spring due to an increase in spring temperatures. The rate of change we observed in spring migration timing due to changes in temperature was identical to or slightly greater than those reported in studies from other countries. The spring arrival of the Narcissus Flycatcher Ficedula narcissina and the Japanese Thrush Turdus cardis, both long-distance summer migrants to the nearby mountains, became earlier (advanced), however, for reasons that remained unclear. Median capture date in autumn was significantly associated with year for five species. Of these, the median capture date of the Japanese White-eye Zosterops japonicus, a resident and wandering bird, and the Black-faced Bunting Emberiza spodocephala, a wandering bird, advanced annually, while for the Japanese Robin Luscinia akahige and two other species (all long-distance migrants), it was delayed. We hypothesize that forest succession from a simple pine forest to a mixed forest with well-developed sub-canopy and shrub layers may have strongly influenced the Japanese White-eye and the Black-faced Bunting due to changes in population structure in the study area, resulting in an earlier median autumn capture date. Forest succession may also have influenced the Japanese Robin's food resources, enabling it to stay longer in the study area and resulting in a delay in autumn departure date. Thus, changes in bird migration timing differ according to different environmental factors in spring and autumn.

Spatial variation in bird pollination and its mitigating effects on the genetic diversity of pollen pools accepted by Camellia japonica trees within a population at a landscape level.

Bird pollination can vary spatially in response to spatial fluctuations in flowering even within plant populations. In this study, we examined the hypothesis that the spatial variation in bird pollination may induce mitigating effects, which maintains or increases genetic diversity of pollen pools at local sites with low flowering densities. To test this hypothesis, we analyzed the landscape-level genetic effects within a population of Camellia japonica on the pollen pools accepted by individuals in two reproductive years by using genotypes at eight microsatellite loci of 1323 seeds from 19 seed parents. Regression analyses using the quadratic models of correlated paternity between pollen pools against spatial distances between the seed-parent pairs revealed not only local pollination but also some amount of long-distance pollen dispersal. The genetic diversity of pollen pools accepted by seed parents tended to be negatively related to the densities of flowering individuals near the seed parents during winter (when the effective pollination of C. japonica is mediated mostly by Zosterops japonica). We show that the low density of flowering individuals may induce the expansion of the foraging areas of Z. japonica and consequently increase the genetic diversity of pollen pools. This spatial variation in bird pollination may induce the mitigating effects on the C. japonica population. The comparisons between the two study years indicate that the overall pattern of bird pollination and the genetic effects described here, including the mitigating effects, may be stable over time.

Manipulating social information to promote frugivory by birds on a Hawaiian Island.

Animals across a range of taxa use social information when foraging. Fruit-eating vertebrates are no exception and use social information to find fruit, which may ultimately affect plant populations via seed dispersal. In many systems, mutualistic relationships between fruiting plants and frugivores are critical to maintain ecosystem functioning, especially in the tropics. On the island of O'ahu, Hawaii, USA, all native, fruit-eating birds are extinct and several plant species are experiencing reduced recruitment likely due to a lack of seed dispersal. Over the years, numerous bird species, many of which are frugivorous, have been introduced to the island. Yet, introduced birds may not recognize native fruits as a resource and social information may be needed for introduced frugivores to target and feed on native fruits. We investigated whether social information, in the form of broadcasted bird vocalizations, of introduced birds could increase visitations and more importantly frugivory on focal fruiting plants. We also tested whether the visitation rates of introduced bird species to focal plants were influenced by conspecific and/or heterospecific vocalizations. We conducted 80 playback experiments at native and introduced fruiting plants, and compared responses to silent control periods. Four times as many frugivores were detected and 10 times more frugivory events were recorded at plants with broadcasted vocalizations compared to control periods. The Japanese White-eye (Zosterops japonicus) exhibited the strongest response to both conspecific and heterospecific playbacks. White-eyes also consumed the most fruit from the widest array of plant species during trials. Introduced birds that use social information and readily identify novel resources may more effectively colonize new areas. We suggest that the White-eye's use of social information may help to support their robust population on O'ahu. Ecosystems throughout the world are affected by the loss of mutualistic relationships, many of which provide valuable ecological services. As humans continue to modify environments, novel conservation approaches may be required to maintain important ecological functions. The use of social information to facilitate frugivory may not only be important in Hawaii, but in other tropical systems where key frugivorous species are lost or abundances have been reduced.

Large-scale tree mortality from Rapid Ohia Death negatively influences avifauna in lower Puna, Hawaii Island, USA

Abstract ‘Ōhi’a lehua (Metrosideros polymorpha) is the principle tree species in forests across the Hawaiian Islands and provides critical foraging and nesting habitat for native passerines. Rapid Ohia Death (ROD), caused by the vascular wilt fungus Ceratocystis lukuohia and the canker pathogen C. huliohia, was first detected in the Puna District of Hawaii Island in 2010. It affects all life stages of ‘ōhi’a and as of July 2018 had spread to an estimated 40,469 ha across Hawaii Island. To determine the impact of ROD on the forest bird community we conducted point counts in lowland ‘ōhi’a forest in 2016 and compared them to counts from 2003 to 2004, before the appearance of ROD. We found an increase in species diversity and a significant decrease in the densities of a native Hawaiian honeycreeper, the Hawaii Amakihi (Chlorodrepanus virens), and the nonnative Japanese White-eye (Zosterops japonicus). Yellow-fronted Canary (Crithagra mozambica) and Saffron Finch (Sicalis flaveola), 2 nonnative passerines associated with the shrub layer and more open habitats, were only detected in 2016. Proportion of survey points occupied were comparable between survey periods, but relative abundances were generally lower. Hawaii Amakihi densities declined by 79% and Japanese White-eye densities declined by 33%. Our findings suggest that the loss of ‘ōhi’a canopy due primarily to ROD has adversely affected populations of native Hawaii Amakihi and nonnative Japanese White-eye, 2 of the most abundant species of lowland Hawaiian forests.

Seasonality and Prevalence of Pollen Collected from Hawaiian Nectarivorous Birds1

Hawaiian nectarivorous forest birds play a vital ecological role as pollinators in Hawaiian ecosystems. However, little is known about what nectar resources are utilized by Hawai‘i's nectarivorous birds, how seasonality influences nectar availability, and how nectar preference differs by bird species. We sampled pollen from the heads of ‘i‘iwi (Drepanis coccinea), ‘apapane (Himatione sanguinea), Hawai‘i ‘amakihi (Chlorodrepanis virens), and the non-native Japanese white-eye (Zosterops japonicas) captured at Hakalau Forest National Wildlife Refuge on Hawai‘i Island. ‘Ōhi‘a (Metrosideros polymorpha) was the most prevalent pollen species, observed throughout the sampling period while other pollen species were more seasonal in occurrence. Consistent with the peak flowering phenology of the plant species, pollen from koa (Acacia koa), māmane (Sophora chrysophylla), and gorse (Ulex europaeus) plant speciesweremore commonly sampled frombirds in the winter months, while ‘ōhelo (Vaccinium reticulatum), ‘ākala (Rubus hawaiensis), and blackberry (Rubus argutus)were more prevalent during the spring months.We also found an association between bird species and pollen resources, with ‘i‘iwi and Hawai‘i ‘amakihi having a higher diversity of pollen than ‘apapane and Japanese white-eye, which primarily had just ‘ōhi‘a. These results demonstrate that ‘ōhi‘a is likely the most important nectar resource for Hawai‘i's nectar feeding birds, but seasonally abundant nectar may be important for some species.

Molecular evidence suggests radical revision of species limits in the great speciator white-eye genus Zosterops

White-eyes (Zosterops spp.) are a group of small passerines distributed across the Eastern Hemisphere that have become a textbook example of rapid speciation. However, traditional taxonomy has relied heavily on conservative plumage features to delimit white-eye species boundaries, resulting in several recent demonstrations of misclassification. Resolution of confused taxonomy is important in order to correctly delimit species and identify taxa which may require conservation, particularly in Asia where the songbird trade is decimating wild populations. In this study, we aim to untangle multiple instances of confused taxonomic treatment in three large, widespread Asian wastebasket species complexes of white-eye (Oriental White-eye Zosterops palpebrosus, Japanese White-eye Zosterops japonicus and Mountain White-eye Zosterops montanus) renowned for their conservative morphology. Using mitochondrial DNA from 173 individuals spanning 42 taxa, we uncovered extensive polyphyly in Z. palpebrosus and Z. japonicus and propose some radically revised species limits under which former members of Z. palpebrosus and Z. japonicus would be reassigned into four and two different species, respectively. The revised taxonomy results in a net loss of two previously recognized species and a net gain of two newly recognized species, leading to significant taxonomic change but a lack of additional species-level diversity. One of the newly elevated species, Zosterops melanurus from Java and Bali, is also the world’s most heavily traded songbird and requires urgent conservation attention.