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Psittacine beak and feather disease virus (BFDV) is a widespread and highly pathogenic virus in parrots. The disease typically presents with feather and beak abnormalities, along with possible immune system suppression. No cure or commercialized vaccine is currently available. Our understanding of the Psittacine beak and feather disease often comes from infected individuals with visible symptoms. Limited knowledge exists regarding the pathology and role of asymptomatic individuals in disease transmission. Asymptomatic individuals could shed the virus in their crop secretion, feces, or feathers. In this study, we investigated the temporal change in the viral load in feather and fecal samples from 17 asymptomatic Rosy-faced Lovebirds (Agapornis roseicollis) using qPCR. Our results showed that most of the individuals had very low viral load, while three individuals with high viral load at the beginning of the experiment were observed to exhibit a decreasing trend in viral load in both fecal and feather samples. Surprisingly, the viral load in an individual can drop from a high level to an undetectable level within three months. This suggests that BFDV infection might not be lethal or highly pathogenic for some individuals. We also showed that the viral load in feathers was higher than in feces.

Psittacosis, or parrot fever, is a zoonotic disease caused by Chlamydia species associated with birds. One of the causative agents of the disease is Chlamydia psittaci, which is commonly carried by psittacine and other bird species, can be highly pathogenic and virulent to humans. In Hong Kong, a city with high population density, psittacosis is a notifiable disease with over 60% of cases in the last decade resulting in hospitalization. However, the sources of transmission of C. psittaci and its prevalence in pet birds in Hong Kong are currently unknown. To evaluate the risks of psittacosis transmission through pet birds, we tested the presence of C. psittaci and determined its genotypes in samples obtained from 516 captive birds from households, pet shops, and a veterinary hospital in Hong Kong. Results revealed that five samples (0.97%), collected from budgerigars and cockatiels, were C. psittaci-positive, while four (80%) of them were obtained from pet shops. Our phylogenetic analysis revealed that all identified strains belonged to Genotype A and showed high similarity to other sequences of this genotype obtained from various geographical locations and host species, including mammals. Our findings provide evidence for the presence of Chlamydia psittaci and shed light on its sources in captive birds in Hong Kong. They highlight the potential zoonotic risks associated with this pathogen, which can affect both humans and wild birds.

Abstract Background Understanding the interactions between bat flies and host bats offer us fundamental insights into the coevolutionary and ecological processes in host-parasite relationships. Here, we investigated the identities, host specificity, and patterns of host association of bat flies in a subtropical region in East Asia, which is an understudied region for bat fly research. Methods We used both morphological characteristics and DNA barcoding to identify the bat fly species found on 11 cavernicolous bat species from five bat families inhabiting Hong Kong. We first determined the phylogenetic relationships among bat fly species. Then, we elucidated the patterns of bat-bat fly associations and calculated the host specificity of each bat fly species. Furthermore, we assembled the mitogenomes of three bat fly species from two families (Nycteribiidae and Streblidae) to contribute to the limited bat fly genetic resources available. Results We examined 641 individuals of bat flies and found 20 species, of which many appeared to be new to science. Species of Nycteribiidae included five Nycteribia spp., three Penicillidia spp., two Phthiridium spp., one Basilia sp., and one species from a hitherto unknown genus, whereas Streblidae included Brachytarsina amboinensis, three Raymondia spp., and four additional Brachytarsina spp. Our bat-bat fly association network shows that certain closely related bat flies within Nycteribiidae and Streblidae only parasitized host bat species that are phylogenetically more closely related. For example, congenerics of Raymondia only parasitized hosts in Rhinolophus and Hipposideros, which are in two closely related families in Rhinolophoidea, but not other distantly related co-roosting species. A wide spectrum of host specificity of these bat fly species was also revealed, with some bat fly species being strictly monoxenous, e.g. nycteribiid Nycteribia sp. A, Phthiridium sp. A, and streblid Raymondia sp. A, while streblid B. amboinensis is polyxenous. Conclusions The bat fly diversity and specificity uncovered in this study have shed light on the complex bat-bat fly ecology in the region, but more bat-parasite association studies are still needed in East Asian regions like China as a huge number of unknown species likely exists. We highly recommend the use of DNA barcoding to support morphological identification to reveal accurate host-ectoparasite relationships for future studies. Graphical Abstract

Abstract Global declines in shorebird populations resulting from foraging habitat loss have been recently reported, and the situation within the East Asian‐Australasian Flyway (EAAF) is particularly concerning. Despite previous studies that analyzed the foraging niches of shorebirds worldwide, the dietary niche dynamics of shorebirds coexisting in Asia are very poorly understood. This study is therefore among the early few that aim to unveil the trophic organization of shorebirds in a subtropical wetland within the EAAF which is vital for species conservation. Our study first determined the dietary spectra of more than 10 shorebird species, such as Calidris ferruginea (near threatened), Charadrius leschenaultii, and Pluvialis squatarola, by applying DNA metabarcoding with 18S and COI markers to fecal DNA. The diet of Tringa stagnatilis was also characterized, which was previously undescribed. Shorebirds that occurred in the wetland consumed a variety of food items, primarily a high abundance of malacostracans, mollusks, annelids, insects, and some arachnids. Different proportions of plant materials were also detected in many shorebird species. Using the data, we then revealed clear patterns of inter‐ and intraspecific variations between these shorebirds. Importantly, we specifically compared the similarities of the spring diets among seven sympatric shorebird species. We found that the dietary compositions of the seven species have segregated from each other to varying levels, but the many similar taxa we identified in the diets among these shorebirds imply that these populations of shorebirds could be competing at different levels. Thus, any reductions in the abundance and diversity of these important food resources would likely intensify their inter‐ and intraspecific competition, and simultaneously threaten the survival of multiple species. With these findings, conservation measures must be taken to protect and monitor the vital food resources for these energy‐deprived shorebirds during migration.

Abstract Extensive loss of natural wetlands caused by changes in land use largely diminishes the food resources essential for the survival of migratory waterbirds. Globally, the decline in waterbird populations in East Asia is the most serious, with 64% of these populations showing a decreasing trend. In this study, we applied DNA metabarcoding to examine the spatiotemporal variations and diversities in the dietary compositions of migratory waterbirds in a natural/artificial wetland complex in Asia. By investigating 110 fecal samples from the endangered black-faced spoonbill (Platalea minor) wintering in the wetland, our results show that P. minor had a broad dietary spectrum. The birds fed on at least 26 species in the classes Actinopterygii and Malacostraca, with Mugiliformes, Cichliformes, and Gobiiformes being the main taxa in their diets. Our results also demonstrated clear patterns of the spatiotemporal variations between the roosting groups and intraspecific variations between the individuals, which potentially reflect some of their feeding habits, and the probable usage of different habitat types in the wetland complex. Using high-throughput sequencing, we were able to elucidate the food resources that are critical to P. minor non-invasively, this method can also be used to provide invaluable information for the conservation of many other waterbird species.

Parrots are the most traded birds internationally, mainly to be used as companion pets, which threatens the global biodiversity. Using the large dataset derived from the Convention on International Trade in Endangered Species of Wild Fauna and Flora (CITES), we uncovered the spatial-temporal changes in trade volumes and sources of parrots, the topology of the trade network, and the factors behind the global parrot trade in the past 42 years (1975–2016). We found that more than 16 million live CITES-listed parrots in 321 species were traded internationally within that period. There were large changes in the temporal trend of global parrot trade volumes and spatial patterns of trade hubs. These changes appeared to be influenced by the trade restrictions in some of the leading traders and the occurrence of pandemic zoonosis, such as the H5N1 avian influenza. Developing states in Western and Southeast Asia have emerged as the most recently developed parrot trade hubs, with South Africa and Europe being some of the major suppliers. The sources of parrots being supplied internationally has also gradually shifted from wild-caught to captive-sourced. Wild-caught individuals of some parrot species, currently classified as Endangered, were traded substantially until 2013. We demonstrated that parrot species with larger wild population sizes, more color morphs, and those in the Least Concern category of the IUCN Red List, were being traded internationally in higher quantities. The GDP per capita and the aging index of states were also correlated with the net import quantities of parrots. Based on our findings, we suggested that greater scrutiny of parrots traded in large volumes, many of which are not monitored in the wild, should be considered. We advocate the uplisting of a few endangered species from Appendix II to I, using an accreditation system to prevent the laundering of wild-caught parrots into captive-bred ones, and conducting more research on newly emerged importers to protect wild parrot populations.