Larus Novaehollandiae Research Articles

The faecal microbiome of the Australian silver gull contains phylogenetically diverse ExPEC, aEPEC and Escherichia coli carrying the transmissible locus of stress tolerance

Wildlife are implicated in the dissemination of antimicrobial resistance, but their roles as hosts for Escherichia coli that pose a threat to human and animal health is limited. Gulls (family Laridae) in particular, are known to carry diverse lineages of multiple-antibiotic resistant E. coli, including extra-intestinal pathogenic E. coli (ExPEC). Whole genome sequencing of 431 E. coli isolates from 69 healthy Australian silver gulls (Chroicocephalus novaehollandiae) sampled during the 2019 breeding season, and without antibiotic selection, was undertaken to assess carriage in an urban wildlife population. Phylogenetic analysis and genotyping resolved 123 sequence types (STs) representing most phylogroups, and identified diverse ExPEC, including an expansive phylogroup B2 cluster comprising 103 isolates (24 %; 31 STs). Analysis of the mobilome identified: i) widespread carriage of the Yersinia High Pathogenicity Island (HPI), a key ExPEC virulence determinant; ii) broad distribution of two novel phage elements, each carrying sitABCD and iii) carriage of the transmissible locus of stress tolerance (tLST), an element linked to sanitation resistance. Of the 169 HPI carrying isolates, 49 (48 %) represented diverse B2 isolates hosting FII-64 ColV-like plasmids that lacked iutABC and sitABC operons typical of ColV plasmids, but carried the serine protease autotransporter gene, sha. Diverse E. coli also carried archetypal ColV plasmids (52 isolates; 12 %). Clusters of closely related E. coli (<50 SNVs) from ST58, ST457 and ST746, sourced from healthy gulls, humans, and companion animals, were frequently identified. In summary, anthropogenically impacted gulls host an expansive E. coli population, including: i) putative ExPEC that carry ColV virulence gene cargo (101 isolates; 23.4 %) and HPI (169 isolates; 39 %); ii) atypical enteropathogenic E. coli (EPEC) (17 isolates; 3.9 %), and iii) E. coli that carry the tLST (20 isolates; 4.6 %). Gulls play an important role in the evolution and transmission of E. coli that impact human health.

Genomic analysis of Citrobacter from Australian wastewater and silver gulls reveals novel sequence types carrying critically important antibiotic resistance genes

Antimicrobial resistance (AMR) is a major public health concern, and environmental bacteria have been recognized as important reservoirs of antimicrobial resistance genes (ARGs). Citrobacter, a common environmental bacterium and opportunistic pathogen in humans and other animals, has been largely understudied in terms of its diversity and AMR potential. Whole-genome (short-read) sequencing on a total of 77 Citrobacter isolates obtained from Australian silver gull (Chroicocephalus novaehollandiae) (n = 17) and influent wastewater samples (n = 60) was performed, revealing a diverse Citrobacter population, with seven different species and 33 sequence types, 17 of which were novel. From silver gull using non-selective media we isolated a broader range of species with little to no mobilised ARG carriage. Wastewater isolates (selected using Carbapenem- Resistant Enterobacterales (CRE) selective media) carried a heavy burden of ARGs (up to 21 ARGs, conferring resistance to nine classes of antibiotics), with several novel multidrug-resistant (MDR) lineages identified, including C. braakii ST1110, which carried ARGs conferring resistance to eight to nine classes of antibiotics, and C. freundii ST1105, which carried two carbapenemase genes, blaIMP-4 in class 1 integron structure, and blaKPC-2. Additionally, we identified an MDR C. portucalensis isolate carrying blaNDM-1, blaSHV-12, and mcr-9. We identified IncC, IncM2, and IncP6 plasmids as the likely vectors for many of the critically important mobilised ARGs. Phylogenetic analyses were performed to assess any epidemiological linkages between isolation sources, demonstrating low relatedness across sources beyond the ST level. However, these analyses did reveal some closer relationships between strains from disparate wastewater sources despite their collection some 13,000 km apart. These findings support the need for future surveillance of Citrobacter populations in wastewater and wildlife populations to monitor for potential opportunistic human pathogens.

Proximity to human settlement is directly related to carriage of critically important antimicrobial-resistant Escherichia coli and Klebsiella pneumoniae in Silver Gulls

Human population and activities play an important role in dissemination of antimicrobial resistant bacteria. This study investigated the relationship between carriage rates of critically important antimicrobial-resistant (CIA-R) Escherichia coli and Klebsiella pneumoniae by Silver Gulls and their proximity to human populations. Faecal swabs (n = 229) were collected from Silver Gulls across 10 southern coastline locations in Western Australia (WA) traversing 650 kms. The sampling locations included main town centres and remote areas. Fluoroquinolone and extended-spectrum cephalosporin-resistant E. coli and K. pneumoniae were isolated and tested for antimicrobial sensitivity. Genome sequencing was performed on n = 40 subset out of 98 E. coli and n = 14 subset out of 27 K. pneumoniae isolates to validate phenotypic resistance profiles and determine the molecular characteristics of strains. CIA-R E. coli and K. pneumoniae were detected in 69 (30.1 %) and 20 (8.73 %) of the faecal swabs respectively. Two large urban locations tested positive for CIA-R E. coli (frequency ranging from 34.3 % to 84.3 %), and/or for CIA-R K. pneumoniae (frequency ranging from 12.5 % to 50.0 %). A small number of CIA-R E. coli (3/31, 9.7 %) were identified at a small tourist town, but no CIA-R bacteria were recovered from gulls at remote sites. Commonly detected E. coli sequence types (STs) included ST131 (12.5 %) and ST1193 (10.0 %). Five K. pneumoniae STs were detected which included ST4568, ST6, ST485, ST967 and ST307. Resistance genes including blaCTX-M-3, blaCTX-M-15 and blaCTX-M-27 were identified in both bacterial species. High-level colonisation of CIA-R E. coli and K. pneumoniae in Silver Gulls in and around urban areas compared to remote locations substantiates that anthropogenic activities are strongly associated with acquisition of resistant bacteria by gulls.

Impact of COVID-19 on pest birds (Silver Gulls Larus novaehollandiae) on a popular tourist island

During the COVID-19 pandemic, Rottnest Island, Western Australia, a popular tourist destination, was closed to the public for 72 days (from 25 March 2020 to 5 June), so that it could be used as a quarantine facility. Silver Gulls Larus novaehollandiae were surveyed in the main settlement area over 429 days, beginning at the commencement of the quarantine period, with a focus on a previously identified problem area, the shopping mall. These surveys allowed for the comparison of Silver Gull numbers with and without the presence of easily accessible anthropogenic food. The number of Gulls was extremely low during the quarantine period, followed by a 578% increase in the same period the following year when visitors returned. During the period of food scarcity, many of the Gulls appeared to have left the Island, which suggests that the number of pest birds on Rottnest Island can be influenced by the amount of anthropogenic food available to them.

Molecular evidence for introgressive hybridization in New Zealand masked gulls

We used mitochondrial DNA (mtDNA) gene sequences and nuclear microsatellite loci to investigate the extent and outcome of hybridization between the Black‐billed Gull Chroicocephalus bulleri and the Red‐billed Gull Chroicocephalus novaehollandiae scopulinus in New Zealand. Six of 26 sampled Black‐billed Gulls possessed mtDNA typical of Red‐billed Gulls, but allele frequencies at six polymorphic microsatellites provided little evidence of mixed ancestry expected in very recent hybrids. None of the Red‐billed Gulls sampled from different colonies possessed Black‐billed Gull mtDNA expected in the reciprocal cross, suggesting that hybridization in the two species typically occurs between female Red‐billed Gulls and Black‐billed Gull males. The lack of any hybrid signal in the nuclear loci indicates that there has been extensive backcrossing with Black‐billed Gulls, effectively diluting the Red‐billed Gull nuclear DNA contribution. Divergence of Red‐billed Gulls and Black‐billed Gulls occurred approximately 250 000 years ago, indicating that unsorted ancestral polymorphism is an unlikely alternative to hybridization. Comparing demographic models within an approximate Bayesian computation (ABC) framework, we confirm that the observed patterns cannot result from incomplete lineage sorting. Using an ABC random forest approach, we determined that the most likely model explaining the data is a recent introgression scenario, whereby unidirectional gene flow is re‐established following a period of strict isolation. The ability of Black‐billed and Red‐billed Gulls to successfully interbreed shows that despite significant differentiation (FST &gt; 0.3), there has been insufficient time for the two species to develop complete reproductive isolation. The apparent one‐way transfer of Red‐billed Gull mtDNA into Black‐billed Gulls and extensive backcrossing argues against cytoplasmic–nuclear genome incompatibilities between the two species. We hypothesize that the specific mate recognition system cued on colours of soft parts normally functions to prevent hybridization, but that it can break down under demographic conditions where there is a shortage of available mates and a surplus of females in the Red‐billed Gull population. The high incidence of introgression in Black‐billed Gulls conflicts with field observations that interbreeding is extremely rare.

Genomic Analysis of an I1 Plasmid Hosting a sul3-Class 1 Integron and blaSHV-12 within an Unusual Escherichia coli ST297 from Urban Wildlife.

Wild birds, particularly silver gulls (Chroicocephalus novaehollandiae) that nest near anthropogenic sites, often harbour bacteria resistant to multiple antibiotics, including those considered of clinical importance. Here, we describe the whole genome sequence of Escherichia coli isolate CE1867 from a silver gull chick sampled in 2012 that hosted an I1 pST25 plasmid with blaSHV-12, a β-lactamase gene that encodes the ability to hydrolyze oxyimino β-lactams, and other antibiotic resistance genes. Isolate CE1867 is an ST297 isolate, a phylogroup B1 lineage, and clustered with a large ST297 O130:H11 clade, which carry Shiga toxin genes. The I1 plasmid belongs to plasmid sequence type 25 and is notable for its carriage of an atypical sul3-class 1 integron with mefB∆260, a structure most frequently reported in Australia from swine. This integron is a typical example of a Tn21-derived element that captured sul3 in place of the standard sul1 structure. Interestingly, the mercury resistance (mer) module of Tn21 is missing and has been replaced with Tn2-blaTEM-1 and a blaSHV-12 encoding module flanked by direct copies of IS26. Comparisons to similar plasmids, however, demonstrate a closely related family of ARG-carrying plasmids that all host variants of the sul3-associated integron with conserved Tn21 insertion points and a variable presence of both mer and mefB truncations, but predominantly mefB∆260.

Interspecies Transmission of CMY-2-Producing Escherichia coli Sequence Type 963 Isolates between Humans and Gulls in Australia.

ABSTRACTEscherichia coli sequence type 963 (ST963) is a neglected lineage closely related to ST38, a globally widespread extraintestinal pathogenic ST causing urinary tract infections (UTI) as well as sepsis in humans. Our current study aimed to improve the knowledge of this understudied ST by carrying out a comprehensive comparative analysis of whole-genome sequencing data consisting of 31 isolates from silver gulls in Australia along with another 80 genomes from public resources originating from geographically scattered regions. ST963 was notable for carriage of cephalosporinase gene blaCMY-2, which was identified in 99 isolates and was generally chromosomally encoded. ST963 isolates showed otherwise low carriage of antibiotic resistance genes, in contrast with the closely related E. coli ST38. We found considerable phylogenetic variability among international ST963 isolates (up to 11,273 single nucleotide polymorphisms [SNPs]), forming three separate clades. A major clade that often differed by 20 SNPs or less consisted of Australian isolates of both human and animal origin, providing evidence of zoonotic or zooanthropogenic transmission. There was a high prevalence of virulence F29:A-:B10 pUTI89-like plasmids within E. coli ST963 (n = 88), carried especially by less variable isolates exhibiting ≤1,154 SNPs. We characterized a novel 115,443-bp pUTI89-like plasmid, pCE2050_A, that carried a traS:IS5 insertion absent from pUTI89. Since IS5 was also present in a transposition unit bearing blaCMY-2 on chromosomes of ST963 strains, IS5 insertion into pUTI89 may enable mobilization of the blaCMY-2 gene from the chromosome/transposition unit to pUTI89 via homologous recombination.IMPORTANCE We have provided the first comprehensive genomic study of E. coli ST963 by analyzing various genomic and phenotypic data sets of isolates from Australian silver gulls and comparison with genomes from geographically dispersed regions of human and animal origin. Our study suggests the emergence of a specific blaCMY-2-carrying E. coli ST963 clone in Australia that is widely spread across the continent by humans and birds. Genomic analysis has revealed that ST963 is a globally dispersed lineage with a remarkable set of virulence genes and virulence plasmids described in uropathogenic E. coli. While ST963 separated into three clusters, a unique specific clade of Australian ST963 isolates harboring a chromosomal copy of AmpC β-lactamase encoding the gene blaCMY-2 and originating from both humans and wild birds was identified. This phylogenetically close cluster comprised isolates of both animal and human origin, thus providing evidence of interspecies zoonotic transmission. The analysis of the genetic environment of the AmpC β-lactamase-encoding gene highlighted ongoing evolutionary events that shape the carriage of this gene in ST963.

Urban Wildlife Crisis: Australian Silver Gull Is a Bystander Host to Widespread Clinical Antibiotic Resistance.

ABSTRACTThe Australian silver gull is an urban-adapted species that frequents anthropogenic waste sites. The enterobacterial flora of synanthropic birds often carries antibiotic resistance genes. Whole-genome sequence analyses of 425 Escherichia coli isolates from cloacal swabs of chicks inhabiting three coastal sites in New South Wales, Australia, cultured on media supplemented with meropenem, cefotaxime, or ciprofloxacin are reported. Phylogenetically, over 170 antibiotic-resistant lineages from 96 sequence types (STs) representing all major phylogroups were identified. Remarkably, 25 STs hosted the carbapenemase gene blaIMP-4, sourced only from Five Islands. Class 1 integrons carrying blaIMP and blaOXA alongside blaCTX-M and qnrS were notable. Multiple plasmid types mobilized blaIMP-4 and blaOXA-1, and 121 isolates (28%) carried either a ColV-like (18%) or a pUTI89-like (10%) F virulence plasmid. Phylogenetic comparisons to human isolates provided evidence of interspecies transmission. Our study underscores the importance of bystander species in the transmission of antibiotic-resistant and pathogenic E. coli.IMPORTANCE By compiling various genomic and phenotypic data sets, we have provided one of the most comprehensive genomic studies of Escherichia coli isolates from the Australian silver gull, on media containing clinically relevant antibiotics. The analysis of genetic structures capturing antimicrobial resistance genes across three gull breeding colonies in New South Wales, Australia, and comparisons to clinical data have revealed a range of trackable genetic signatures that highlight the broad distribution of clinical antimicrobial resistance in more than 170 different lineages of E. coli. Conserved truncation sizes of the class 1 integrase gene, a key component of multiple-drug resistance structures in the Enterobacteriaceae, represent unique deletion events that are helping to link seemingly disparate isolates and highlight epidemiologically relevant data between wildlife and clinical sources. Notably, only the most anthropogenically affected of the three sites (Five Islands) was observed to host carbapenem resistance, indicating a potential reservoir among the sites sampled.

Comparing methods for monitoring nest debris using silver gulls as a case study

Global plastics production is increasing exponentially and contributing to significant pollution of the marine environment. Of particular concern is ingestion and entanglement risks for marine wildlife, including when items such as rope are incorporated into nest structures. These events are commonly documented using photographic and visual surveys, and each presents a number of challenges and benefits for species conservation and monitoring. Here we compare an invasive (i.e., removing debris from nests) and non-invasive (i.e., photographs) sampling method for quantifying nest debris using the silver gull (Chroicocephalus novahollandiae) as a case study. Overall, 17 debris items were detected in 9% of gull nests. While the use of photographs to monitor nest debris is increasingly popular, the invasive method detected one additional debris item not identified using photography. We therefore recommend caution for nest debris and other monitoring programs where identifying small or cryptic items may require a high level of skill.

Epidemic HI2 Plasmids Mobilising the Carbapenemase Gene blaIMP-4 in Australian Clinical Samples Identified in Multiple Sublineages of Escherichia coli ST216 Colonising Silver Gulls.

Escherichia coli ST216, including those that carry blaKPC-2, blaFOX-5, blaCTX-M-15 and mcr-1, have been linked to wild and urban-adapted birds and the colonisation of hospital environments causing recalcitrant, carbapenem-resistant human infections. Here we sequenced 22 multiple-drug resistant ST216 isolates from Australian silver gull chicks sampled from Five Islands, of which 21 carried nine or more antibiotic resistance genes including blaIMP-4 (n = 21), blaTEM-1b (n = 21), aac(3)-IId (n = 20), mph(A) (n = 20), catB3 (n = 20), sul1 (n = 20), aph(3”)-Ib (n = 18) and aph(6)-Id (n = 18) on FIB(K) (n = 20), HI2-ST1 (n = 11) and HI2-ST3 (n = 10) plasmids. We show that (i) all HI2 plasmids harbour blaIMP-4 in resistance regions containing In809 flanked by IS26 (HI2-ST1) or IS15DI (HI2-ST3) and diverse metal resistance genes; (ii) HI2-ST1 plasmids are highly related to plasmids reported in diverse Enterobacteriaceae sourced from humans, companion animals and wildlife; (iii) HI2 were a feature of the Australian gull isolates and were not observed in international ST216 isolates. Phylogenetic analyses identified close relationships between ST216 from Australian gull and clinical isolates from overseas. E. coli ST216 from Australian gulls harbour HI2 plasmids encoding resistance to clinically important antibiotics and metals. Our studies underscore the importance of adopting a one health approach to AMR and pathogen surveillance.

Inferred predation of Fairy Tern eggs by Ruddy Turnstones at Rottnest Island, Western Australia, an internationally significant shorebird site

Ruddy Turnstones Arenaria interpres have been identified as egg-predators at seabird and shorebird colonies, including gull and tern colonies in the tropics and Northern Hemisphere. The Australian Fairy Tern Sternula nereis nereis is a threatened (Environment Protection and Biodiversity Conservation Act 1999: Vulnerable) coastal seabird, whose breeding behaviour and ecology expose it to a wide range of threats. This study describes inferred predation on Fairy Tern eggs at a small breeding colony on Rottnest Island, Western Australia, by Ruddy Turnstones, a previously unsuspected predator for thisspecies. Unlike the behavioural response shown towards Silver Gulls Larus novaehollandiae and Australian Ravens Corvus coronoides, which includes collective group defence and dive-bombing, Fairy Terns showed a lack of aggression towards Turnstones within the colony. The lack of a behavioural response suggests that the Terns did not recognise the Turnstones as predators, which may increase the risk of egg-predation. This study suggests that we should be alert to threats from unsuspected predators, which have the potential to reduce the breeding success of this Vulnerable tern.

Escherichia coli Sequence Type 457 Is an Emerging Extended-Spectrum-β-Lactam-Resistant Lineage with Reservoirs in Wildlife and Food-Producing Animals.

Silver gulls carry phylogenetically diverse Escherichia coli, including globally dominant extraintestinal pathogenic E. coli (ExPEC) sequence types and pandemic ExPEC-ST131 clades; however, our large-scale study (504 samples) on silver gulls nesting off the coast of New South Wales identified E. coli ST457 as the most prevalent. A phylogenetic analysis of whole-genome sequences (WGS) of 138 ST457 samples comprising 42 from gulls, 2 from humans (Australia), and 14 from poultry farmed in Paraguay were compared with 80 WGS deposited in public databases from diverse sources and countries. E. coli ST457 strains are phylogenetic group F, carry fimH145, and partition into five main clades in accordance to predominant flagella H-antigen carriage. Although we identified considerable phylogenetic diversity among the 138 ST457 strains, closely related subclades (<100 SNPs) suggested zoonotic or zooanthroponosis transmission between humans, wild birds, and food-producing animals. Australian human clinical and gull strains in two of the clades were closely related (≤80 SNPs). Regarding plasmid content, country, or country/source, specific connections were observed, including I1/ST23, I1/ST314, and I1/ST315 disseminating blaCMY-2 in Australia, I1/ST113 carrying blaCTX-M-8 and mcr-5 in Paraguayan poultry, and F2:A-:B1 plasmids of Dutch origin being detected across multiple ST457 clades. We identified a high prevalence of nearly identical I1/ST23 plasmids carrying blaCMY-2 among Australian gull and clinical human strains. In summary, ST457 is a broad host range, geographically diverse E. coli lineage that can cause human extraintestinal disease, including urinary tract infection, and displays a remarkable ability to capture mobile elements that carry and transmit genes encoding resistance to critically important antibiotics.

Implications of Foraging and Interspecies Interactions of Birds for Carriage of Escherichia coli Strains Resistant to Critically Important Antimicrobials.

Globally, gulls have been associated with carriage of high levels of Escherichia coli strains resistant to critically important antimicrobials (CIAs), a major concern, as these antimicrobials are the sole alternative or one among only a few alternatives available to treat severe life-threatening infections in humans. Previous studies of Australian silver gulls demonstrated high levels of resistance to CIAs, particularly fluoroquinolone and extended-spectrum cephalosporins, among E. coli strains (carriage at 24% and 22%, respectively). This study aimed to identify and characterize strains from four distinct bird species inhabiting a common coastal environment, determine the frequency of carriage of CIA-resistant E. coli strains, and examine if these resistant clones and their resistance-encoding mobile genetic elements (MGEs) could be transmitted between species. CIA-resistant E. coli was detected in silver gulls (53%), little penguins (11%), and feral pigeons (10%), but not in bridled terns. In total, 37 different sequence types (STs) were identified, including clinically significant human-associated lineages, such as ST131, ST95, ST648, ST69, ST540, ST93, ST450, and ST10. Five main mobile genetic elements associated with blaCTX-M-positive E. coli strains isolated from three bird species were detected. Examination of clonal lineages and MGEs provided indirect evidence of transfer of resistance between bird species. The carriage of CIA-resistant E. coli by gulls and pigeons with proximity to humans, and in some instances food-producing animals, increases the likelihood of further bidirectional dissemination.IMPORTANCE It has been shown that 20% of Australian silver gulls carry drug-resistant Escherichia coli strains of anthropogenic origin associated with severe diseases, such as sepsis and urinary tract infections, in humans. To further characterize the dynamics of drug-resistant E. coli in wildlife populations, we investigated the carriage of critically important antimicrobial (CIA) drug-resistant E. coli in four bird species in a common environment. Our results indicated that gulls, pigeons, and penguins carried drug-resistant E. coli strains, and analysis of mobile genetic elements associated with resistance genes indicated interspecies resistance transfer. Terns, representing a bird species that forages on natural food sources at sea and distant from humans, did not test positive for drug-resistant E. coli This study demonstrates carriage of CIA-resistant bacteria in multiple bird species living in areas commonly inhabited by humans and provides further evidence for a leapfrog effect of resistance in wildlife, facilitated by feeding habits.

Silver gull harassment of humpback whales in Exmouth Gulf, Western Australia

We share observations of silver gulls (Chroicocephalus novaehollandiae) harassing humpback whales (Megaptera novaeangliae) in Exmouth Gulf, Western Australia, between August and October in 2018 and 2019. Sixteen events were recorded of gulls pecking at the skin of 16 mothers and 2 calves resting on the surface. Data were collected opportunistically from a research vessel covering 5474.2km (565h). Events were documented through photographs and unmanned aerial vehicle video recordings and persisted for an average minimum time of 20.73min (range 2.50–46.85min). At least one event of a gull consistently gouging in a pre-existing lesion was recorded on a mother. Changes in behavioural activity from the whales, which varied from slipping under the surface to travelling and performing instantaneous behavioural events, were observed in 94% (15/16) of events. These are the first known records of birds attacking humpback whales. The results are comparable to early events of kelp gull (Larus dominicanus) harassment of southern right whales (Eubalaena australis) off Península Valdés, Argentina, where events have escalated over the past 50 years to consistent attacks on the whales’ skin and blubber. Future research is required to monitor the trajectory of these interactions to inform management.

Opportunistic sampling of wild native and invasive birds reveals a rich diversity of adenoviruses in Australia.

Little is known about the diversity of adenoviruses in wild birds and how they have evolved and are maintained in complex ecosystems. In this study, 409 samples were collected from woodland birds caught for banding (droppings), birds submitted to a wildlife hospital (droppings and tissues), silver gulls (droppings or tissues), and feral pigeons (Columbia livia; oral, cloacal swabs, or tissues) from the Greater Sydney area in NSW, Australia. Additional samples were from native pigeons and doves (swabs) presented to the Healesville Sanctuary, VIC, Australia. Samples were screened for adenovirus DNA using degenerate primers and polymerase chain reaction. Adenovirus sequences were detected in eighty-three samples representing thirty-five novel amino acid sequences. Fourteen novel sequences were atadenoviruses, seven were aviadenoviruses, twelve were siadenoviruses, and one was a mastadenovirus. Sequences from passerine birds were predominately found to form a single lineage within the atadenoviruses, a second lineage in the siadenoviruses, and a third smaller aviadenovirus lineage. These viruses appeared to have co-evolved with a diverse group of woodland birds that share similar habitat. Evidence for host/virus co-evolution in some viruses and a wide host range in others was observed. A high prevalence of adenovirus infection was found in rainbow lorikeets (Trichoglossus haematodus), galahs (Eolophus roseicapilla), and sulphur-crested cockatoos (Cacatua galerita). Sequences were either identical to or mapped to already established lineages in the Aviadenovirus, Siadenovirus, and Atadenovirus genera, suggesting a possible origin of the psittacine adenoviruses in ancestral Australian psittacine birds. The sequences of passerine and psittacine origin provided insight into diversity and structure of the Atadenovirus genus and demonstrated for the first-time viruses of passerine origin in the Aviadenovirus genus. Four unrelated adenovirus sequences were found in silver gull samples (Chroicocephalus novaehollandiae), including one of pigeon origin, suggesting environmental virus exposure. Three pigeon adenovirus types were detected in feral pigeons and infection prevalence was high. Evidence for host switching between invasive species and native species and native species and invasive species was documented. A variant of a murine adenovirus was detected in kidney tissue from two bird species suggesting mouse to bird transmission.

Resistance to critically important antimicrobials in Australian silver gulls (Chroicocephalus novaehollandiae) and evidence of anthropogenic origins

Antimicrobial resistance (AMR) to critically important antimicrobials (CIAs) amongst Gram-negative bacteria can feasibly be transferred amongst wildlife, humans and domestic animals. This study investigated the ecology, epidemiology and origins of CIA-resistant Escherichia coli carried by Australian silver gulls (Chroicocephalus novaehollandiae), a gregarious avian wildlife species that is a common inhabitant of coastal areas with high levels of human contact. Sampling locations were widely dispersed around the perimeter of the Australian continent, with sites separated by up to 3500 km. WGS was used to study the diversity and molecular characteristics of resistant isolates to ascertain their epidemiological origin. Investigation of 562 faecal samples revealed widespread occurrence of extended-spectrum cephalosporin-resistant (21.7%) and fluoroquinolone-resistant (23.8%) E. coli. Genome sequencing revealed that CIA-resistant E. coli isolates (n = 284) from gulls predominantly belonged to human-associated extra-intestinal pathogenic E. coli (ExPEC) clones, including ST131 (17%), ST10 (8%), ST1193 (6%), ST69 (5%) and ST38 (4%). Genomic analysis revealed that gulls carry pandemic ExPEC-ST131 clades (O25:H4 H30-R and H30-Rx) and globally emerging fluoroquinolone-resistant ST1193 identified among humans worldwide. Comparative analysis revealed that ST131 and ST1193 isolates from gulls overlapped extensively with human clinical isolates from Australia and overseas. The present study also detected single isolates of carbapenem-resistant E. coli (ST410-blaOXA-48) and colistin-resistant E. coli (ST345-mcr-1). The carriage of diverse CIA-resistant E. coli clones that strongly resemble pathogenic clones from humans suggests that gulls can act as ecological sponges indiscriminately accumulating and disseminating CIA-resistant bacteria over vast distances.

Using raptors to disperse pest birds in Victoria

Birds are considered to be pests when they damage infrastructure and crops as well as being a health risk and a social nuisance. Here we detail some case studies where we used trained raptors to disperse populations of pest Long-billed Cacatua tenuirostris and Little Corellas C. sanguinea , Sulphur-crested Cockatoos C. galerita and Silver Gulls Chroicocephalus novaehollandiae in Victoria. We describe the situations where the technique works best and compare it with other methods of managing pest birds. Using raptors to disperse pest birds seems to be a cost-effective management tool only when the target area is small, the period over which damage occurs is limited, and when the damage caused by the pest species is costly.

Are there conservation implications for kangaroos feeding on sea birds?

This research note documents an observation of a wild western grey kangaroo (Macropus fuliginosus) feeding on a dead silver gull (Chroicocephalus novaehollandiae) at Lucky Bay in the Cape Le Grand National Park on the south coast of Western Australia. Published evidence suggests that this behaviour is not unique and could be widespread in Western Australia and further afield. We consider why the kangaroo may be feeding on the dead gull and possible implications for conservation programs relying on poison meat baits to control introduced species.

Building use by urban commensal avifauna in Melbourne central business district, Australia

ABSTRACTThe foraging and perching behaviours of urban commensal birds are well studied but disproportionately focused on green spaces (e.g. parks, backyards) rather than inner city urban sites. The relationship between building use and foraging was examined in free-ranging urban birds of the central business district (CBD) of Melbourne, Victoria, Australia during 2015–2016. The presence of common birds on urban buildings was attributable both to the time of day (Feral Pigeons and Silver Gulls in the morning, and House Sparrows in the evening) and the architectural period of the building (Feral Pigeons, House Sparrows and Common Mynas were found mostly on historic buildings). The proximity of buildings to tree cover had a significant impact on the presence of House Sparrows. Silver Gulls were present in large numbers only in areas with the least disturbance from traffic and trams (and their overhead wires). Feeding behaviours constituted a small portion of time budgets for all species (mean 4.3%; range 0–11%) compared to perching (28.2; 0–60%), walking (30.4; 0–80%) and flying (23.0; 0–54%), indicating that food sources were highly abundant and requiring little effort to acquire. Management implications of this study support control of food availability rather than costly and ineffective bird deterrent systems on buildings.

Vancomycin-resistant enterococci with vanA and vanB genes in Australian gulls.

This study is revealing the possible dissemination of vancomycin-resistant enterococci (VRE) from humans into the wildlife. We studied silver gulls (Chroicocephalus novaehollandiae) in Australia as potential carriers and reservoirs of VRE with acquired vancomycin resistance. In New South Wales (Australia), we have found two multi-resistant isolates belonging to Enterococcus faecium (sequence type 341, vanB genotype) and Enterococcus dispar (vanA genotype). Based on our knowledge, this is the first report of VRE in Australian wildlife.