Australian Ibis Research Articles

Landscape and habitat characteristics jointly drive the urban distribution of a nuisance species

Identifying environmental variables that affect the distribution of pest and/or nuisance species promotes effective management strategies by improving urban planning and the targeted application of direct interventions like population control. Australian white ibis Threskiornis moluccus are considered a nuisance species throughout Australia, having increased significantly in abundance in coastal urban landscapes following declines in their native inland habitats over the past three decades. Few management interventions thus far have successfully reduced conflicts between ibis and humans, necessitating a better understanding of conditions driving ibis distribution and abundance. We surveyed 26 ibis colonies throughout the Moreton Bay region in central eastern Australia and quantified the effects of a range of spatial (e.g. connectivity with waste management facilities, urban land and wetlands) and habitat (e.g. nesting tree species, density and size) variables on ibis and nest abundance. Ibis and their nests were most abundant at sites within 10 km of waste management facilities, and < 60 m from residential or industrial estates. Ibis were also more abundant at sites with tree canopy height < 10 m and lower tree species richness. Nests were most abundant on water bound islands with tree density > 0.5 trees/m2. Urbanisation had contrasting effects, with nest numbers increasing with higher connectivity (i.e. closer proximity) to urban land, while ibis numbers decreased (relative to waste management facilities). Multifaceted approaches are required for controlling ibis populations, including restricting access to anthropogenic food resources, managing the condition of remnant habitats, and considering population control at sites with high connectivity to foraging grounds.

Mermaids and bin chickens: Australian teenagers’ engagement with screen stories in the on-demand age

Australian teenagers have grown up with abundant choices in digital screen entertainment including social media, gaming, and global streaming video services such as Netflix. This participatory audience study investigates how, why and to what extent Australian teenagers engage with drama and movies in their daily lives, including Australian stories. The research findings show that Australian teens enjoy watching long-form screen stories on their favourite streaming services and that on-demand delivery is critical to their viewing preferences. Although many remember with affection the Australian drama they watched as children, teens now place a low priority on a screen story being Australian. A sophisticated audience that particularly values diverse and inclusive representation, teens’ deprioritising of Australian content – and linear television – has profound implications for policy, for Australian screen production and for public service broadcasters the Australian Broadcasting Corporation and the Special Broadcasting Service.

Chlamydia Psittaci ST24: Clonal Strains of One Health Importance Dominate in Australian Horse, Bird and Human Infections.

Chlamydia psittaci is traditionally regarded as a globally distributed avian pathogen that can cause zoonotic spill-over. Molecular research has identified an extended global host range and significant genetic diversity. However, Australia has reported a reduced host range (avian, horse, and human) with a dominance of clonal strains, denoted ST24. To better understand the widespread of this strain type in Australia, multilocus sequence typing (MLST) and ompA genotyping were applied on samples from a range of hosts (avian, equine, marsupial, and bovine) from Australia. MLST confirms that clonal ST24 strains dominate infections of Australian psittacine and equine hosts (82/88; 93.18%). However, this study also found novel hosts (Australian white ibis, King parrots, racing pigeon, bovine, and a wallaby) and demonstrated that strain diversity does exist in Australia. The discovery of a C. psittaci novel strain (ST306) in a novel host, the Western brush wallaby, is the first detection in a marsupial. Analysis of the results of this study applied a multidisciplinary approach regarding Chlamydia infections, equine infectious disease, ecology, and One Health. Recommendations include an update for the descriptive framework of C. psittaci disease and cell biology work to inform pathogenicity and complement molecular epidemiology.

Ibis and the city: bogan kitsch and the avian revisualization of Sydney

The Australian White Ibis (Ibis) ( Threskiornis molucca) is one of three endemic Ibis species in Australia. In a short time frame beginning in the 1970s, this species has moved from inland waterways to urban centres along the eastern and southeastern seaboards, Darwin and the Western Australian southwest. Today Ibis are at home in cities across the country, where they thrive on the food waste, water resources and nesting sites supplied by humans. In this article, the authors focus on Sydney to argue that the physical and cultural inroads of Ibis, and the birds’ urban homeliness, are resignifying urban surfaces and the multispecies ecologies in which contemporary Australians operate. They explore how the very physical and sensory presence of Ibis disrupts the assumptions of many urban Australians, and visitors from overseas, that cities are human-centric or human-dominant, non-hybrid assemblages. They also introduce to this discussion of disrupted human expectations a cultural parallel, namely, the recent rise of Ibis in popular culture as an icon-in-the-making of the nation and as a totem of the modern Australian city itself. This trend exemplifies an avian-led revisualization of urban spaces, and is notable for its visual appeals to Ibis kitsch, and to working class or ‘bogan’ sensibilities that assert their place alongside cosmopolitan visions of being Australian. Sometimes kitsch Ibis imagery erupts across the urban landscape, as occurs with many Ibis murals. At other times it infiltrates daily life on clothing, on football club, university and business logos, as tattoos on people’s skin, and as words in daily idiom, confirmed by terms such as ‘picnic pirates’, ‘tip turkeys’ and ‘bin chickens’. The article uses a visual vignette methodology to chart Ibis moves into Sydney and the realms of representation alike, and thus to reveal how new zoöpolitical entanglements are being made in the 21st century.

Ibis and spoonbill chick growth and energy requirements: implications for wetland and water management

Colonial-nesting waterbirds such as ibis and spoonbills (Threskiornithidae) can account for a significant proportion of energy flow through wetlands, particularly during large breeding events. However when food availability is reduced, chicks may starve and adults may abandon nests. If the energy required to rear chicks could be calculated, data quantifying prey energy value and availability could be used to develop landscape scale management targets to ensure that food requirements are met to support chicks until they attain independence, thereby maximising recruitment. We calculated ibis and spoonbill chick biometrics and energy requirements through (a) an international literature review, extracting and synthesising the best available growth and energy data; (b) new measurements of ibis and spoonbill chick biometrics for selected species; and (c) analysis of the resulting databases to construct growth curves and predict energy requirements for selected species. Here we present the first models of Royal Spoonbill growth and of Royal Spoonbill and Australian White Ibis chick energy requirements. The total energy estimated to raise a single Royal Spoonbill chick from hatching to independence was 71,290 kJ and for an Australian White Ibis chick was 67,160 kJ. Using prey energy values from the literature, extrapolations indicate that for either species, a nesting event of 1000 nests producing three chicks per nest would require an estimated ten tonnes of freshwater crayfish (Cherax destructor) or eight tonnes of invasive juvenile carp (Cyprinus carpio) to support chicks from hatching to independence. Effective water and wetland management is critical to optimise both energy availability in foraging sites and breeding success.

OpenDropOff: An open‐source, low‐cost drop‐off unit for animal‐borne devices

Abstract The use of animal‐borne devices in wildlife studies is increasing due to the miniaturization of sensors and reductions in component costs. Retrieval of animal‐borne devices is often advantageous for several reasons, including data retrieval and animal welfare considerations; however, commercially available drop‐off units are often prohibitively expensive and/or unreliable. Here, we present ‘OpenDropOff’, an open‐source, low‐cost electronic drop‐off unit for remotely detaching animal‐borne sensors from individuals. OpenDropOff devices function by using heat, produced by running an electrical current through resistance wire (nichrome), to melt nylon (e.g. fishing) line, detaching sensors from animals at or after a pre‐determined time. OpenDropOff can be constructed using commercially available components (costing &lt; USD $15 in total; approximately 10% or less of many commercially available drop‐off units) and can be customized to fit project‐ and species‐specific needs. Fourteen OpenDropOff devices have been field deployed on koalas (Phascolarctos cinereus) (n = 11), swamp wallaby (Wallabia bicolor) (n = 1), Australian brush turkey (Alectura lathami) (n = 1) and Australian white ibis (Threskiornis molucca) (n = 1), with the only detachment failure occurring after a device was damaged during the koala’s unrelated death. OpenDropOff devices provide a wider range of researchers with a reliable, cost‐effective tool for detaching animal‐borne sensors. Their use could allow researchers to more efficiently allocate project resources, and their flexibility provides an opportunity to mitigate animal welfare concerns surrounding the use of animal‐borne devices.

Clean bill of health? Towards an understanding of health risks posed by urban ibis

Urban waterbirds are considered both serious pests and inspiring wildlife. Ibis and gulls are often vilified due to their dirty appearance and disruption of outdoor activities, while ducks are affectionately fed in parks. However, all waterbirds are potential reservoirs of zoonotic pathogens. In Sydney (Australia), we documented the relative prevalence of arbovirus exposure and Salmonella shedding in 72 Australian White Ibis (Threskiornis moluccus) at 2 urban sites in 2003 during a management cull and in 2015 as a response to increased public interest. We sampled during a period of peak human arbovirus and Salmonella infection risk in late summer and early autumn. In 2015, antibodies for the endemic West Nile virus Kunjin strain (WNV) were detected in one bird. While not indicative of immediate public health risk, this highlights that an animal with a history of exposure was present or moved into a region not previously known to have endemic WNV activity. However, the movement patterns of this individual and WNV host competency of this species are unknown. An absence of other antibody responses suggests that ibis are not important viral reservoirs or flaviviruses are not widespread in Sydney. Assays failed to detect Salmonella in 2015, but 25% of individuals were positive in 2003. Further monitoring of the arguable health hazard represented by urban T. moluccus will facilitate informed decisions and solutions to urban bird and wetland management challenges.

Rain drives foraging decisions of an urban exploiter.

Foraging decisions tend to drive individuals toward maximising energetic gains within a patchy environment. This study aims to determine the extent to which rainfall, and associated changes in food availability, can explain foraging decisions within a patchy urbanised landscape, using the Australian white ibis as a model species. Ibis density, food consumption rates and food abundance (both natural and anthropogenic) were recorded during dry and wet weather within urban parks in Sydney, Australia. Rainfall influenced ibis density in these urban parks. Of the four parks assessed, the site with the highest level of anthropogenic food and the lowest abundance of natural food (earthworms), irrespective of weather, was observed to have three times the density of ibis. Rainfall significantly increased the rate of earthworm consumption as well as their relative availability in all sites. Overall, these density and consumption measures indicate that anthropogenic derived foods, mainly from direct feeding by people, explain the apparent distribution of ibis across urban parks. However, there was evidence of prey-switching when the availability of natural foods increased following rainfall, perhaps reflecting selection of particular nutrients.

Rainfall events drive foraging choices by an urban coloniser

Using a seven-year data set of visitation of an inner city park by the Australian white ibis, we investigated whether rain events were correlated with ibis abundance in the park. The park is associated with high levels of anthropogenic food, but relatively low levels of natural food sources. For all magnitudes of rainfall tested, ibis abundance significantly decreased after a rainfall event, although stronger responses were associated with higher rainfall, with a 46% decline in ibis abundance following rainfall events of ≥60 mm. Average ibis abundance was higher during the dry, non-breeding period than during the breeding period, and variation associated with rainfall was particularly pronounced in the non-breeding period. However, the rainfall response was still evident in both periods. Results suggest that rainfall influences the ibis distribution in urban centres either by decreasing anthropogenic food supplied to the birds, forcing the birds to relocate to forage, or increasing the amount of natural food available elsewhere, or a combination of the two. Increased rainfall intensified the response by ibis, and our results demonstrate the importance of climatic processes on the behaviour of urban birds.

Macronutrient selection of free-ranging urban Australian white ibis (Threskiornis moluccus)

Lay SummaryWhen offered a choice of experimental foods high in protein, lipid or carbohydrate, urban Australian white ibis showed a preference for high-carbohydrate foods. This is in contrast to the typical composition of their natural prey, which are low in carbohydrates and higher in protein and lipids. Furthermore, the proportion of macronutrients selected by ibis was affected by competition and previous rainfall, giving further insight into the complexities of a native species foraging in urban environments.Twitter: @SeanCoogs

A probable Australian White Ibis Threskiornis moluccus × Straw-necked Ibis T. spinicollis hybrid

We observed a probable juvenile Australian White Ibis Threskiornis moluccus × Straw-necked Ibis T. spinicollis hybrid on the Lachlan River catchment, New South Wales, in November 2016. Photographs, combined with observations, demonstrate phenotypic characteristics of both these ibis species. The bird had a pattern on the wing similar to the Australian White Ibis but coloration on the body similar to the Straw-necked Ibis. To our knowledge, this is only the second report of a probable hybrid between these two species in the wild, and the first report documented with photographs

A probable Australian White Ibis Threskiornis moluccus × Straw-necked Ibis T. spinicollis hybrid

We observed a probable juvenile Australian White Ibis Threskiornis moluccus × Straw-necked Ibis T. spinicollis hybrid on the Lachlan River catchment, New South Wales, in November 2016. Photographs, combined with observations, demonstrate phenotypic characteristics of both these ibis species. The bird had a pattern on the wing similar to the Australian White Ibis but coloration on the body similar to the Straw-necked Ibis. To our knowledge, this is only the second report of a probable hybrid between these two species in the wild, and the first report documented with photographs.

Changes in distribution of waterbirds following prolonged drought reflect habitat availability in coastal and inland regions.

Provision of suitable habitat for waterbirds is a major challenge for environmental managers in arid and semiarid regions with high spatial and temporal variability in rainfall. It is understood in broad terms that to survive waterbirds must move according to phases of wet–dry cycles, with coastal habitats providing drought refugia and inland wetlands used during the wet phase. However, both inland and coastal wetlands are subject to major anthropogenic pressures, and the various species of waterbird may have particular habitat requirements and respond individualistically to spatiotemporal variations in resource distribution. A better understanding of the relationships between occurrence of waterbirds and habitat condition under changing climatic conditions and anthropogenic pressures will help clarify patterns of habitat use and the targeting of investments in conservation. We provide the first predictive models of habitat availability between wet and dry phases for six widely distributed waterbird species at a large spatial scale. We first test the broad hypothesis that waterbirds are largely confined to coastal regions during a dry phase. We then examine the contrasting results among the six species, which support other hypotheses erected on the basis of their ecological characteristics. There were large increases in area of suitable habitat in inland regions in the wet year compared with the dry year for all species, ranging from 4.14% for Australian White Ibis to 31.73% for Eurasian Coot. With over half of the suitable habitat for three of the six species was located in coastal zones during drought, our study highlights the need to identify and conserve coastal drought refuges. Monitoring of changes in extent and condition of wetlands, combined with distribution modeling of waterbirds, will help support improvements in the conservation and management of waterbirds into the future.

From pest to partner: rethinking the Australian White Ibis in the more-than-human city

Calls to rethink our ethical and political responsibilities with nonhuman others abound recent work in cultural geography. Such work unpacks the more-than-human agencies reshaping and rematerialising our bodies and subjective knowledges. This article uncovers the coproduction of human knowledges and urban spaces by examining the problematic migration of the Australian White Ibis into Australian urban localities. We put forth a storied approach to human-ibis relations, capturing the multiple and situated experiences materialising our urban relations with the species. Drawing on ibis ethology, media narratives, personal and interviewee stories, we explore how ibis take part in the co-constitution of urban spaces and identities. In particular, we examine how the ibis as a pest narrative is mobilised and reproduced in public and media discourses that shape the species identity and influence modes of relating. Both the publics and our own personal intra-actions with ibis shed light on conceptions of nonhuman belonging, death and human desires for living-with. This article forwards a cosmopolitical approach to provoke a reconceptualisation of our ethical and political responsibility with urban ibis. We question the narrative of ibis-as-pest to forward ideas of living-with that provokes new modes of relating, uncomfortable for either party. Within these precarious relations, possibilities open for nonhierarchical modes of cohabitation, challenging our political and ethical responsibilities in living-with uncomfortable others.

Modelling urban populations of the Australian White Ibis (Threskiornis molucca) to inform management

AbstractSince the 1970s, populations of the Australian White Ibis (Threskiornis molucca) have dramatically increased in many Australian urban centres. Managers of ibis are currently focusing on limiting this bird's reproductive success in order to reduce population sizes or at least halt further increases in urban areas. Here we use data on nesting success and survival for three populations of ibis around greater Sydney to develop an age‐structured population model. The estimated growth rate for all populations combined was about 1.5 % per year and for individual sites were more variable at −1, −7, and 9 %. For all populations, growth rates were most sensitive (based on elasticity analyses) to the survival of adults and least sensitive to fecundity, especially of 3 year olds. Further exploration of the importance of fecundity rates, which are relatively poorly known for these populations, suggests that rates of &lt;0.4 fledglings per nest per year is very likely to lead to a population decline (λ less than lower bound of 95 % CI). Conversely, positive population growth is nearly assured (λ greater than upper bound of 95 % CI) for fecundities of &gt;0.7 fledgling per nest per year. The results suggest that ibis from other locations (probably their traditional breeding areas in inland Australia) have immigrated into urban environments as estimated growth rates cannot account for current population sizes. Management strategies must take these findings into account and also consider that ibis are declining in their traditional habitats to avoid exacerbating their decline at a regional scale.

Causes of Morbidity and Mortality of Wild Aquatic Birds at Billabong Sanctuary, Townsville, North Queensland, Australia

Infectious diseases are common causes of significant morbidity and mortality events of wild aquatic birds (WABs) worldwide. Reports of Australian events are infrequent. A 3-yr passive surveillance program investigating the common causes of morbidity and mortality of WABs was conducted at Billabong Sanctuary near Townsville, North Queensland, from April 2007 to March 2010. Forty-two carcasses were obtained and evaluated by clinico-pathologic, histologic, bacteriologic, and virologic (molecular) examinations. Morbidity and mortality were sporadic and more commonly observed in chicks and juvenile birds in April than other months of the year. Morbid birds were frequently unable to walk. Hemorrhagic lesions and infiltration of lymphocytes in various organs were the most common findings in dead birds. Identified bacterial diseases that could cause bird mortality were colibacillosis, pasteurellosis, and salmonellosis. Salmonella serotypes Virchow and Hvittingfoss were isolated from an Australian white ibis (Threskiornis molucca) chick and two juvenile plumed whistling ducks (Dendrocygna eytoni) in April 2007. These strains have been previously isolated from humans in North Queensland. A multiplex real time reverse transcriptase-PCR (rRT-PCR) detected Newcastle disease viral RNA (class 2 type) in one adult Australian pelican (Pelecanus conspicillatus) and a juvenile plumed whistling duck. No avian influenza viral RNA was detected from any sampled birds by the rRT-PCR for avian influenza. This study identified the public health importance of Salmonella in WABs but did not detect the introduction of the high pathogenicity avian influenza H5N1 virus in the population. A successful network was established between the property owner and the James Cook University research team through which dead birds, with accompanying information, were readily obtained for analysis. There is an opportunity for establishing a long-term passive disease surveillance program for WABs in North Queensland, an important region in Australian biosecurity, thus potentially significantly benefitting public health in the region and the country.

Breeding Flow Thresholds of Colonial Breeding Waterbirds in the Murray-Darling Basin, Australia

Biodiversity on floodplains is under increasing pressure as demand for water for human needs expands. Understanding how waterbirds respond to river flows feeding floodplain wetlands is critical for successful management. We analysed data on breeding by colonial breeding large waders—Eastern Great Egret Ardea modesta, Intermediate Egret Ardea intermedia, Little Egret Egretta garzetta, Nankeen Night Heron Nycticorax caledonicus, Australian White Ibis Threskiornis molucca, Glossy Ibis Plegadis falcinellus, Straw-necked Ibis Threskiornis spinicollis, and Royal Spoonbill Platalea regia—in response to river flow for three wetlands in the Murray-Darling Basin, Australia. Each wetland, which included Barmah-Millewa, the Macquarie Marshes, and Lake Merreti, has a distinctive geomorphology and hydrology. There were clear consistent thresholds of flow producing a >0.7 probability of attempted breeding by most species when a daily flow threshold was exceeded for 30–50 days. Flow characteristics were highly correlated and thresholds could also be expressed in terms of the total flow volume July–December and peak flow in September or October. Below thresholds, there was zero probability of breeding for most species. These minimum thresholds provide critical information for management of these wetlands. Our approach provides an analytical framework for estimating thresholds for other floodplains.

Perfluorinated alkyl acids in water, sediment and wildlife from Sydney Harbour and surroundings

Perfluorinated alkyl compounds (PFCs) including perfluorooctane sulphonate (PFOS) and perfluorooctanoate (PFOA) were measured in environmental samples collected from around Homebush Bay, an urban/industrial area in the upper reaches of Sydney Harbour and Parramatta River estuary. Water, surface sediment, Sea Mullet (Mugil cephalus), Sydney Rock Oyster (Saccostrea commercialis) and eggs of two bird species; White Ibis (Threskiornis molucca), and Silver Gull (Larus novaehollandiae) were analysed. In most samples PFOS was the dominant PFC. Geometric mean PFOS concentrations were 33ng/gww (wet weight) in gull eggs, 34ng/gww in ibis eggs, and 1.8ng/gww and 66ng/gww in Sea Mullet muscle and liver, respectively. In sediment the PFOS geometric mean was 1.5ng/g, in water average PFOS and PFOA concentrations ranged from 7.5 to 21ng/L and 4.2 to 6.4ng/L, respectively. In oysters perfluorododecanoic acid was most abundant, with a geometric mean of 2.5ng/gww.

Crisis Water Management and Ibis Breeding at Narran Lakes in Arid Australia

Narran Lakes is a Ramsar site recognised for its importance for colonial waterbird breeding, which only occurs after large highly variable flooding events. In 2008, 74,095 pairs of ibis bred for the first time in seven years, establishing two contiguous colonies, a month apart. Most (97%) of the colony consisted of the straw-necked ibis (Threskiornis spinicollis) with the remainder consisting of glossy ibis (2%, Plegadis falcinellus) and Australian white ibis (1%, T. molucca). Following cessation of river flows, water levels fell rapidly in the colony site, resulting in a crisis management decision by governments to purchase and deliver water (10,423 Ml) to avert mass desertion of the colonies. There were significant differences in the reproductive success of each colony. In colony 1 60% of eggs hatched and 94% of chicks fledged, while in colony 2 40% of eggs hatched with only 17% of chicks fledging. Statistical analyses found that water depth was a significant variable in determining reproductive success. Rapid falls in water level during the chick stage in colony 2 resulted in decreased chick and overall offspring success. The results of this study identify the impact of upstream water resource development on colonial waterbird breeding and have implications for water management policies.

Foraging distances and habitat preferences of a recent urban coloniser: The Australian white ibis

Australian white ibis populations have increased in many urban areas while traditional inland populations have declined. In instances where conflicts have occurred land managers have been licensed to remove nests and eggs and cull adults at a site scale. With the increase in urban populations and local management of the species, there is a need to understand how ibis are using urban resources and how they move through the urban landscape to identify important resources. To gain a better understanding of the connectedness of local urban populations, we fitted 82 birds with radio transmitters at three common habitats: an urban park, a breeding colony and a landfill. Over a period of 48 weeks we found 45% of birds made movements greater than 10 km, with 13% moving greater than 30 km. Ibis were located at up to nine foraging and seven roost sites, demonstrating the connectedness of the population across the study region. Landfills were identified as a major food resource with 63% of ibis ( n = 82) located therein, while parks supported local foraging with only 27% of ibis ( n = 82) located therein. Our results indicate that ibis showed site fidelity but also interacted on a regional scale within approximately 40 km of their colonies. Accordingly, conservation planning for this species needs to be assessed on a regional basis, not on a localized case-by-case basis. However, further research into the limits of the ‘region’ is required for this highly mobile colonial species.