John M. Martin

The pest status of Australian white ibis (Threskiornis molucca) in urban situations and the effectiveness of egg-oil in reproductive control

The Australian white ibis (Threskiornis molucca) is considered to be an urban pest along the east coast of Australia. The non-specific diet and broad habitat requirements of ibis have facilitated their successful exploitation of the urban environment. Ibis are considered a pest because they pose a threat to aircraft safety, scavenge food at waste-management sites, cafes and parks, and compete with other native species for food and habitat. This study assesses a new ibis-management technique, the application of ‘egg-oil’ to suppress hatching. On other species, egg-oiling has been shown to be environmentally safe and socially preferable to culling adult birds. Approximately 5 mL of food-grade canola oil was sprayed upon each egg, and both incubator and field trials were used to investigate the efficacy of this technique on ibis and to determine the optimal application time and frequency of egg-oil. Treatment eggs were given an application of oil during the 23-day incubation period either once per week, or once early ( 18 days) incubation. All four treatments were observed to be 100% effective at preventing ibis eggs from hatching during the laboratory trial and more than 98% effective during the field trial. These results indicate that applying canola oil to ibis eggs once, at any time, during the 23-day incubation period is sufficient to prevent ibis eggs from hatching. The field trial also showed that 30% of ibis, across the four oiling treatments, continued to incubate the unviable eggs for up to 54 days longer than the normal incubation period. Given that ibis are multibrooded, raising up to three successful clutches in a breeding season, the increased time devoted to incubating oil-treated eggs could reduce the opportunity for multiple broods, compared with conventional egg destruction. The egg-oil technique offers an additional tool for land managers to conduct ibis reproduction control, which should reduce the amount of time required to conduct ibis management, consequently reducing the cost to land managers.

Population and breeding trends of an urban coloniser: the Australian white ibis

Context. In the Sydney region, the population of Australian white ibis has dramatically increased from rare observations in the 1950s to a breeding season peak of 8900 in 2008, resulting with human–wildlife conflicts. Within natural habitats across the eastern states, the ibis population has declined, yet within urban environments ibis have been lethally managed for over 30 years. However, limited ecological and no regional population data are available for the Sydney region. Aims. The present study of ibis in the Sydney region aims to (1) establish the abundance of the population during the breeding and non-breeding seasons, (2) determine whether the population is increasing, and (3) identify the importance of different foraging and roosting sites. Methods. Across the Sydney region, we surveyed 54 discrete sites for 2.5 years. At each site, we recorded the number of adult, juvenile and nestling ibis as well as the number of active nests. The 54 sites were grouped into 15 areas consisting of five landfills and 10 suburbs, which were assessed with ANOVA. Key results. The ibis population of the Sydney region doubled from a peak of 4200 in 2006 to 8900 in 2008. Seasonal fluctuations saw adults migrating in to the region to breed, and adults and juveniles dispersing following breeding. On average, 44% of the population was located foraging within landfills, whereas 80% of nesting activity occurred within ‘urban-natural’ habitats. Conclusions. Seasonal fluctuations indicated that the ibis population of Sydney is connected with the broader state and national population. Landfills provided an abundant foraging resource that supported extended breeding, including consistent nesting for a 19-month period. Implications. The present study indicated that any localised population management has consequences beyond the immediate or regional population and, consequently, regional management plans or actions need to consider the long-term status of the eastern states’ population. Urban conflicts need to be resolved with human education and a conservation agenda, preferably with the provision of refuge habitat where birds are not disturbed.

Behavioural adaptation of a bird from transient wetland specialist to an urban resident.

Dramatic population increases of the native white ibis in urban areas have resulted in their classification as a nuisance species. In response to community and industry complaints, land managers have attempted to deter the growing population by destroying ibis nests and eggs over the last twenty years. However, our understanding of ibis ecology is poor and a question of particular importance for management is whether ibis show sufficient site fidelity to justify site-level management of nuisance populations. Ibis in non-urban areas have been observed to be highly transient and capable of moving hundreds of kilometres. In urban areas the population has been observed to vary seasonally, but at some sites ibis are always observed and are thought to be behaving as residents. To measure the level of site fidelity, we colour banded 93 adult ibis at an urban park and conducted 3-day surveys each fortnight over one year, then each quarter over four years. From the quarterly data, the first year resighting rate was 89% for females (n = 59) and 76% for males (n = 34); this decreased to 41% of females and 21% of males in the fourth year. Ibis are known to be highly mobile, and 70% of females and 77% of males were observed at additional sites within the surrounding region (up to 50 km distant). Our results indicate that a large proportion of ibis have chosen residency over transience both within the study site and across the broader urban region. Consequently the establishment of refuge breeding habitat should be a priority localised management may be effective at particular sites, but it is likely to have an impact across the broader population.

The use of Cattle Ear-Tags as Patagial Markers for Large Birds—a Field Assessment on Adult and Nestling Australian White Ibis

Abstract. To test the effectiveness of patagial marking with cattle ear-tags for Australian White Ibis (Threskiornis molucca), 105 adults and 58 nestlings were fitted with tags on each wing. Resighting frequency of adults, survival of nestlings, breeding behavior and foraging movements were monitored. The resighting frequency of wing-tagged adults was compared with resightings of 160 adults marked with colored leg-bands. Survival rates of wing-tagged nestlings were compared with an equal sample of 58 nestlings fitted with colored leg-bands. Over six months, 96% of tagged adults were resighted and there was no indication of impaired flight, with foraging movements ranging up to 30 km. Wing-tagged adults were more likely (40%) than color-banded adults (28%) to be detected in a one-off survey three months after marking and 65% of tagged birds were observed nesting. Higher mortality was observed among smaller nestlings (<1100 g) compared with larger nestlings marked with wing tags, but not among those marked with leg bands. Inspection of the wings of two adult and two juvenile birds recaptured 6–8 months after marking indicated only minor feather abrasion, although further study is needed to assess long-term impacts. Because patagially-fitted cattle ear-tags are more visible than colored leg bands, can be fitted quickly with minimal trauma, and seem to have few adverse effects, they appear to be an effective technique for individually marking large adult 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

Assessing the reliability of avian biodiversity measures of urban greenspaces using eBird citizen science data

Assessing the reliability of avian biodiversity measures of urban greenspaces using eBird citizen science data Corey T. Callaghan , Mitchell B. Lyons , John M. Martin , Richard E. Major 3,4 and Richard T. Kingsford 1 Centre for Ecosystem Science, School of Biological, Earth and Environmental Sciences, UNSW, Sydney, Australia, Royal Botanic Gardens and Domain Trust, Sydney, Australia, Australian Museum Research Institute, Australian Museum, Sydney, Australia, Centre for Ecosystem Science, School of Biological, Earth and Environmental Sciences, Sydney, Australia

Avian monitoring – comparing structured and unstructured citizen science

Abstract Context. Citizen science is increasingly used to collect biodiversity data to inform conservation management, but its validity within urban greenspaces remains largely unresolved. Aims. To assess the validity of eBird data for generating biodiversity estimates within an urban greenspace. Methods. We compared data from structured avian surveys with eBird data at an urban greenspace in Sydney during 2012–16, using species richness and Shannon diversity indices. We also compared community composition, using non-metric multidimensional scaling (NMDS) and dissimilarities using non-parametric MANOVA. Key results. Structured surveys had a lower overall species richness (80 versus 116) and Shannon diversity (3.64 versus 3.94) than eBird data, but we found no significant differences when using years as replicates. After standardising the richness and diversity indices by time spent surveying in a given year, structured surveys produced significantly higher biodiversity estimates. Further, when grouped into species occupying different broad habitats, there were no significant differences in waterbird or landbird species richness, or in Shannon diversity between data sources. Conclusions. The most likely explanation for the larger magnitudes of the biodiversity indices from the eBird data is the increase in effort manifested in the number of observers, time spent surveying and spatial coverage. This resulted in increased detection of uncommon species, which in turn accounted for a significant difference (R2 = 0.21, P = 0.015) in overall community composition measured by the two methods. Implications. Our results highlight the opportunities provided by eBird data as a useful tool for land managers for monitoring avian communities in urban areas.

HEMATOLOGY, PLASMA BIOCHEMISTRY, AND URINALYSIS OF FREE-RANGING GREY-HEADED FLYING FOXES (PTEROPUS POLIOCEPHALUS) IN AUSTRALIA

Abstract The grey-headed flying fox (Pteropus poliocephalus) is a species endemic to coastal eastern Australia. This study presents a comprehensive set of biochemistry, hematology, and urinalysis biomarkers from which reference values were derived. Blood samples collected from free-ranging P. poliocephalus were submitted for hematology (n = 140) and plasma biochemistry (n = 161) and urine for urinalysis (n = 95). The values for P. poliocephalus were broadly consistent with those values published for other Australian Pteropus species. Statistically significant within-species age and sex effects were observed: adult P. poliocephalus had higher mean corpuscular volume, mean corpuscular hemoglobin, urea, creatinine, bilirubin, alanine transferase (ALT), protein, globulin, urinary specific gravity, and urinary ketones, whereas subadults had higher mean red blood cell, white blood cell (WBC), lymphocyte, and monocyte counts, and juveniles had higher mean neutrophil count and alkaline phosphatase; male P. poliocephalus had higher mean reticulocyte count, alanine transferase, glucose, and urinary ketones, whereas females had higher mean WBC, lymphocyte, and monocyte counts. The findings inform both clinical and research scenarios for P. poliocephalus in captivity or rehabilitation and for health assessments of free-living populations.

Slow growth and delayed maturation in a Critically Endangered insular flying fox (Pteropus natalis)

Flying foxes (family Pteropodidae) have distinct life histories given their size, characterized by longevity, low reproductive output, and long gestation. However, they tend to decouple the age at which sexual maturity is reached from the age at which they reach adult dimensions. We examined growth, maturation, and reproduction in the Critically Endangered Christmas Island flying fox (Pteropus natalis) to determine the timing of sexspecific life cycle events and patterns of growth. We estimated that juvenile growth in forearm length and body mass increased at a mean rate of 0.029 ± 0.005 mm/day and 0.33 ± 0.07 g/day for both males and females alike. Using these growth rates, we determined that the birth of pups occurs between December and March, with young becoming volant between June and August. The age at maturation for P. natalis is one of the oldest among all bat species. Juvenile males began to mature 15 months after birth and reached maturity 27 months after birth. Females reached maturity 24 months after birth at a significantly smaller body mass (3.6%) and forearm length (1.4%) than males. Significant sexual dimorphism and bimaturation was observed, with juvenile males being 1.5% and adult males being 1.9% larger on average than females for skeletal dimensions only. Growth and maturation are even slower in P. natalis than in the few other Pteropus species studied to date. The slow growth and delayed maturation of P. natalis imply slower potential population growth rates, further complicating the recovery of this Critically Endangered single-island endemic.

Travelling birds generate eco-travellers: The economic potential of vagrant birdwatching

ABSTRACT Avitourism is one of the faster growing subsectors of ecotourism, recognized for its economic value. Much of our current understanding of the economic value of avitourism revolves around bird festivals, migration events, or well-known birdwatching sites. Birdwatchers are a diverse group, some of whom competitively seek vagrant birds (i.e., birds outside their normal geographic range). The economic value from these unpredictable and transient birdwatching events remains poorly known. Using the travel cost method in a readily-quantifiable environment, we estimated that a vagrant Black-backed Oriole in Pennsylvania, United States of America, stimulated travel activity valued at about