Corey Callaghan

Corey Callaghan

Role: PhD Candidate

Contact details: Email:


Phone: +61 421 601 388

Office: D26 Building, UNSW, Kensington 2052

Research Focus:

Currently, more than half (54%) of the world’s population resides in urbanized areas and by 2030 60% of the world’s population will be living in urbanized areas. This has prompted much recent research in urban ecology. Urban greenspaces (e.g., parks, cemeteries, treatment wetlands) are an essential mechanism by which to study urban ecology. In the increasingly developed world there tend to be species, both native and non-native that thrive in heavily developed areas. Urban greenspaces are not only heavily utilized by a variety of taxa, but also by humans. Our ability to preserve and construct urban greenspaces within future urbanization is dependent on our knowledge of their benefits and how they are used. This research intends to investigate the broad role of urban greenspaces throughout urbanized areas. With a focus on birds, I will investigate what greenspace characteristics predict the highest avian biodiversity of urban greenspaces. Alternatively, I will investigate which avian species’ characteristics predict presence in urban environments. A central theme of the research will be the differentiation of native and non-native species. Specifically, I will elucidate associations of native and non-native species’ richness and diversity with particular landcover classes throughout urbanized areas. Lastly, I shift to an anthropogenic focus in order to investigate how humans use urban greenspaces throughout Australia, and what aspects of urban greenspaces drive visitation rates. Ultimately, the results of this research can aid in planning strategies and establishment of sustainable cities worldwide.

Article about birds and humans


Author Date Title Link PDF
Callaghan et al. 2019 Generalists are the most urban-tolerant of birds: an analysis of ecological and life history traits using a novel continuous measure of bird responses to urbanization

Abstract: Identifying which ecological and life history traits influence a species’ tolerance to urbanization is critical to understanding the trajectory of biodiversity in an increasingly urbanizing world. There is evidence for a wide array of contrasting patterns for single trait associations with urbanization. In a continental-scale analysis, incorporating 477 species and > 5,000,000 bird observations, we developed a novel and scalable methodology that evaluated the ecological and life history traits which most influence a species’ adaptability to persist in urban environments. Specifically, we assigned species-specific scores based on continuous measures of response to urbanization, using VIIRS night-time light values (i.e., radiance) as a proxy for urbanization. We identified generalized, phylogenetically controlled patterns: bird species which are generalists (i.e., large niche breadth), with large clutch size, and large residual brain size are among the most urban-tolerant bird species. Conversely, specialized feeding strategies (i.e., insectivores and granivores) were negatively associated with urbanization. Enhancement and persistence of avian biodiversity in urban environments probably relies on protecting, maintaining, and restoring diverse habitats serving a range of life history strategies.

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Callaghan et al. 2018 Travelling birds generate eco-travellers: The economic potential of vagrant birdwatching

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 $223,000 USD or about $3,000 per day over 67 days. Some birdwatchers value rare birds, contributing significant time and financial resources to their viewing. Identifying such significant real economic value from avitourism can help to evaluate competing costs in debate over human land-use scenarios.

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Callaghan et al. 2018 A comment on the limitations of UAVS in wildlife research - the example of colonial nesting waterbirds
Callaghan et al. 2018 Unnatural history: is a paradigm shift of natural history in 21st century ornithology needed?


Natural history, across disciplines, is essential for the continuation of science, especially as we attempt to identify the myriad of threats that biodiversity faces in this rapidly changing world. Recording the natural history of birds is perhaps the most prominent, widespread and long‐standing pursuit of this activity. Yet, there is a distinct decrease in publishing of natural history in the ornithological sciences. Concomitantly, the natural history information being published is often in small and regional journals, less accessible by the global ornithological community. We argue that historical natural history needs a modern reinvigoration, and should focus on placing natural history observations in the context of an anthropogenically altered world – ‘unnatural history’. This includes, but is not limited to, behavioural adaptations, novel diet choices, hybridization and novel adaptations to urbanization. Here, we elaborate on natural history's place in modern ornithology, how this relates to citizen science and the potential cost of ignoring it. Ultimately, increased accessibility of natural history observations, encouragement of amateur ornithologists' participation in professional societies (and vice versa) and targeted citizen science projects are potential mechanisms by which to reinvigorate natural history in 21st century ornithology.

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Lyons et al. 2018 Bird interactions with drones, from individuals to large colonies


Drones are rapidly becoming a key part of the toolkit for a range of scientific disciplines, as well as a range of management and commercial applications. This presents challenges in the context of how drone use might impact on nearby wildlife, especially birds as they might share the airspace. This paper presents observations (from 97 flight hours) and offers preliminary guidance for drone-monitoring exercises and future research to develop guidelines for safe and effective monitoring with drones. Our study sites spanned a range of arid, semi-arid, dunefield, floodplain, wetland, woodland, forest, coastal heath and urban environments in south-eastern and central Australia. They included a nesting colony of >200 000 Straw-necked Ibis Threskiornis spinicollis, the largest drone-based bird-monitoring exercise to date. We particularly focused on behavioural changes towards drones during the breeding season, interactions with raptors, and effects on birds nesting in large colonies—three areas yet to be explored in published literature. Some aggressive behaviour was encountered from solitary breeding birds, but several large breeding bird colonies were surveyed without such issues. With multi-rotor drones, we observed no incidents that posed a threat to birds, but one raptor attacked and took down a fixed-wing drone. In addition to providing observations of interactions with specific bird species, we detail our procedures for flight planning, safe flying and avoidance of birds, and highlight the need for more research into bird– drone interactions, most notably with respect to territorial breeding birds, safety around large raptors, and the effects of drones on the behaviour of birds in large breeding colonies.

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Callaghan et al. 2018 Avian monitoring – comparing structured and unstructured citizen science


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 nonmetric 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.

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Callaghan et al. 2018 The effects of local and landscape habitat attributes on bird diversity in urban greenspaces


Contrasting trajectories of biodiversity loss and urban expansion make it imperative to understand biodiversity persistence in cities. Size‐, local‐, and landscape‐level habitat factors of greenspaces in cities may be critical for future design and management of urban greenspaces in conserving bird biodiversity. Most current understanding of bird communities in cities has come from disparate analyses of single cities, over relatively short time periods, producing limited understanding of processes and characteristics of bird patterns for improved biodiversity management of the world's cities. We analyzed bird biodiversity in 112 urban greenspaces from 51 cities across eight countries, using eBird, a broadscale citizen science project. Species richness and Shannon diversity were used as response variables, while percent tree cover, percent water cover, and vegetation index were used as habitat predictor variables at both a landscape (5 and 25 km radius) and local‐scale level (specific to an individual greenspace) in the modeling process, retrieved using Google Earth Engine. Area of a greenspace was the most important predictor of bird biodiversity, underlining the critical importance of habitat area as the most important factor for increasing bird biodiversity and mitigating loss from urbanization. Surprisingly, distance from the city center and distance from the coast were not significantly related to bird biodiversity. Landscape‐scale habitat predictors were less related to bird biodiversity than local‐scale habitat predictors. Ultimately, bird biodiversity loss could be mitigated by protecting and developing large greenspaces with varied habitat in the world's cities.


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Callaghan et al. 2017 History, Current Distribution, and Status of the Egyptian Goose (Alopochen aegyptiaca) In the Contiguous United States


We summarize the history, current distribution, and status of Egyptian geese (Alopochen aegyptiaca) in the contiguous United States, using published records and the eBird database of bird observations. The area of occupancy for the Egyptian goose has increased throughout the contiguous United States. The species has three populations that appear to be strongholds throughout the United States: Florida, California, and Texas. The potential ecological and economic consequences of an apparent increase in the United States warrant further research on a number of aspects of Egyptian goose biology.

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Callaghan et al. 2017 A probable Australian White Ibis Threskiornis moluccus × Straw-necked Ibis T. spinicollis hybrid

Abstract. 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.

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Callaghan et al. 2017 Assessing the reliability of avian biodiversity measures of urban greenspaces using eBird citizen science data

ABSTRACT. Urban greenspaces are important areas for biodiversity, serving multiple uses, sometimes including conservation and biodiversity management. Citizen science provides a cheap and potentially effective method of assisting biodiversity management in urban greenspaces. Despite this potential, the minimum amount of citizen science data required to adequately represent a community is largely untested. We used eBird data to test the minimum sampling effort required to be confident in results for three biological metrics, species richness, Shannon diversity, and community composition (Bray-Curtis similarity). For our data, from 30 urban greenspaces in North America, for a 90% threshold level, a minimum mean number of 210, 33, and 58 checklists were necessary for species richness, Shannon diversity, and community composition, respectively. However, when we eliminated those species that were present in fewer than 5% of checklists at a given site, there was a marked decrease in mean minimum number of checklists required (17, 9, and 52, respectively). Depending on the ecological questions of interest, eBird data may be a potentially reliable data source in urban greenspaces. We provide a validation methodology using eBird data, with its associated code in the R statistical environment, to provide confidence for land managers and community groups managing urban greenspaces.

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