Register      Login
Wildlife Research Wildlife Research Society
Ecology, management and conservation in natural and modified habitats
RESEARCH ARTICLE (Open Access)

Using citizen science records from iNaturalist to document geographical range outliers in Australian skinks

Feliks Ozolina https://orcid.org/0009-0006-5310-5596 A , Shai Meiri B , Jules E. Farquhar https://orcid.org/0000-0002-1894-7580 A # and David G. Chapple https://orcid.org/0000-0002-7720-6280 A # *
+ Author Affiliations
- Author Affiliations

A School of Biological Sciences, Monash University, Clayton, Vic, Australia.

B School of Zoology, The Steinhardt Museum of Natural History, Tel Aviv University, Tel Aviv, Israel.

* Correspondence to: David.Chapple@monash.edu

# Joint senior authors

Handling Editor: Aaron Wirsing

Wildlife Research 52, WR24060 https://doi.org/10.1071/WR24060
Submitted: 15 April 2024  Accepted: 18 March 2025  Published: 3 April 2025

© 2025 The Author(s) (or their employer(s)). Published by CSIRO Publishing. This is an open access article distributed under the Creative Commons Attribution-NonCommercial-NoDerivatives 4.0 International License (CC BY-NC-ND)

Abstract

Context

Accurately describing a species’ geographical distribution is important for informing research and conservation efforts. The citizen science platform iNaturalist provides a valuable resource for increasing our understanding of species distributions.

Aims

To locate and document geographical range outliers in Australian skinks, and to provide evidence of populations undocumented in the existing literature.

Methods

We compared observations of Australian skinks on iNaturalist to digital range maps from both the Global Assessment of Reptile Distributions (GARD), the International Union for the Conservation of Nature (IUCN), and a recent Australian reptile field guide. Outlying observations were examined to determine whether they were reliable records. We also made statistical comparisons of the characteristics of species with and without iNaturalist observations and outliers both among species range sizes and subfamilies.

Key results

In total, 319 (of ~462) native Australian skink species had iNaturalist records. These species generally had larger range sizes, and skink subfamilies were represented unequally. Eighty-two skink species (25.7%) had at least one geographical range outlier, and 33 (10.3%) had at least one novel range outlier, unrecorded anywhere in the scientific literature. Range size did not affect the likelihood of a species to have outliers, but there was still a difference among subfamilies. We found 656 potentially interesting distribution anomalies. Most were not novel, but 111 were novel observations, including potential accidental translocations of a number of species. Most notably, evidence of an established population of Carlia sexdentata in Darwin, Northern Territory.

Conclusions

Several factors affect how well Australian skink species are represented on iNaturalist, and many species are highly under-represented or unrepresented altogether. Despite this, our method was successful in providing evidence of a number of range anomalies, including some established populations that have not been formally documented. We also showed, through non-novel outliers, that the three map sources used in this study are not always the most accurate source for species distributions in Australian skinks.

Implications

Our method can potentially be applied to many taxa around the world, so as to increase our understanding of species distributions.

Keywords: biological invasion, citizen science, human assisted dispersal, lizard, range extension, reptile, Scincidae, species distribution.

References

Belbin L, Wallis E, Hobern D, Zerger A (2021) The atlas of living Australia: history, current state and future directions. Biodiversity Data Journal 9, e65023.
| Crossref | Google Scholar |

Boakes EH, McGowan PJK, Fuller RA, Chang-qing D, Clark NE, O’Connor K, Mace GM (2010) Distorted views of biodiversity: spatial and temporal bias in species occurrence data. PLoS Biology 8, e1000385.
| Crossref | Google Scholar |

Brown ED, Williams BK (2019) The potential for citizen science to produce reliable and useful information in ecology. Conservation Biology 33, 561-569.
| Crossref | Google Scholar | PubMed |

Caetano GHdO, Chapple DG, Grenyer R, Raz T, Rosenblatt J, Tingley R, Böhm M, Meiri S, Roll U (2022) Automated assessment reveals that the extinction risk of reptiles is widely underestimated across space and phylogeny. PLoS Biology 20, e3001544.
| Crossref | Google Scholar |

Callaghan CT, Mesaglio T, Ascher JS, Brooks TM, Cabras AA, Chandler M, Cornwell WK, Cristóbal Ríos-Málaver I, Dankowicz E, Urfi Dhiya’ulhaq N, Fuller RA, Galindo-Leal C, Grattarola F, Hewitt S, Higgins L, Hitchcock C, James Hung K-L, Iwane T, Kahumbu P, Kendrick R, Kieschnick SR, Kunz G, Lee CC, Lin C-T, Loarie S, Norman Medina M, McGrouther MA, Miles L, Modi S, Nowak K, Oktaviani R, Waswala Olewe BM, Pagé J, Petrovan S, saari cassi , Seltzer CE, Seregin AP, Sullivan JJ, Sumanapala AP, Takoukam A, Widness J, Willmott K, Wüster W, Young AN (2022) The benefits of contributing to the citizen science platform iNaturalist as an identifier. PLoS Biology 20, e3001843.
| Crossref | Google Scholar |

Camaiti M, Evans AR, Hipsley CA, Chapple DG (2021) A farewell to arms and legs: a review of limb reduction in squamates. Biological Reviews 96, 1035-1050.
| Crossref | Google Scholar | PubMed |

Camaiti M, Evans AR, Hipsley CA, Hutchinson MN, Meiri S, Anderson RO, Slavenko A, Chapple DG (2022) A database of the morphology, ecology and literature of the world’s limb-reduced skinks. Journal of Biogeography 49, 1397-1406.
| Crossref | Google Scholar |

Chapple DG, Simmonds SM, Wong BBM (2011) Know when to run, know when to hide: can behavioral differences explain the divergent invasion success of two sympatric lizards? Ecology and Evolution 1, 278-289.
| Crossref | Google Scholar | PubMed |

Chapple DG, Simmonds SM, Wong BBM (2012) Can behavioral and personality traits influence the success of unintentional species introductions? Trends in Ecology & Evolution 27, 57-64.
| Crossref | Google Scholar | PubMed |

Chapple DG, Whitaker AH, Chapple SNJ, Miller KA, Thompson MB (2013) Biosecurity interceptions of an invasive lizard: origin of stowaways and human-assisted spread within New Zealand. Evolutionary Applications 6, 324-339.
| Crossref | Google Scholar | PubMed |

Chapple D, Tingley R, Mitchell N, Macdonald S, Keogh JS, Shea GM, Bowles P, Cox NA, Woinarski JCZ (2019) The action plan for Australian lizards and snakes 2017. CSIRO Publishing, Melbourne, Vic, Australia. Available at https://www.publish.csiro.au/book/7823/#details [accessed 2 December 2023]

Contreras-Díaz RG, Nori J, Chiappa-Carrara X, Peterson AT, Soberón J, Osorio-Olvera L (2023) Well-intentioned initiatives hinder understanding biodiversity conservation: cloaked iNaturalist information for threatened species. Biological Conservation 282, 110042.
| Crossref | Google Scholar |

Crane M, Silva I, Marshall BM, Strine CT (2021) Lots of movement, little progress: a review of reptile home range literature. PeerJ 9, e11742.
| Crossref | Google Scholar |

Di Cecco GJ, Barve V, Belitz MW, Stucky BJ, Guralnick RP, Hurlbert AH (2021) Observing the observers: how participants contribute data to iNaturalist and implications for biodiversity science. BioScience 71, 1179-1188.
| Crossref | Google Scholar |

Farquhar JE, Carlesso A, Pili A, Gale N, Chapple DG (2024) Capturing uncatalogued distribution records to improve conservation assessments of data-deficient species: a case study using the glossy grass skink. Animal Conservation 27, 124-137.
| Crossref | Google Scholar |

Fox J, Weisberg S (2019) An R companion to applied regression. Sage, Thousand Oaks, CA, USA. Available at https://socialsciences.mcmaster.ca/jfox/Books/Companion/

Fraser KC, Davies KTA, Davy CM, Ford AT, Flockhart DTT, Martins EG (2018) Tracking the conservation promise of movement ecology. Frontiers in Ecology and Evolution 6, 150.
| Crossref | Google Scholar |

Gardner MG, Hughall AF, Donellan SC, Hutchinson MN, Foster R (2008) Molecular systematics of social skinks: phylogeny and taxonomy of the Egernia group (Reptilia: Scincidae). Zoological Journal of the Linnean Society 154, 781-794.
| Crossref | Google Scholar |

Gorleri FC, Areta JI (2022) Misidentifications in citizen science bias the phenological estimates of two hard-to-identify Elaenia flycatchers. Ibis 164, 13-26.
| Crossref | Google Scholar |

Gorleri FC, Jordan EA, Roesler I, Monteleone D, Areta JI (2023) Using photographic records to quantify accuracy of bird identifications in citizen science data. Ibis 165, 458-471.
| Crossref | Google Scholar |

Herkt KMB, Skidmore AK, Fahr J (2017) Macroecological conclusions based on IUCN expert maps: a call for caution. Global Ecology and Biogeography 26, 930-941.
| Crossref | Google Scholar |

Homan P (2011) A record of Spencer’s Skink Pseudemoia spenceri from the Victorian Volcanic Plain. The Victorian Naturalist 128, 106-110 Available at https://core.ac.uk/download/pdf/15620514.pdf.
| Google Scholar |

Hortal J, de Bello F, Diniz-Filho JAF, Lewinsohn TM, Lobo JM, Ladle RJ (2015) Seven shortfalls that beset large-scale knowledge of biodiversity. Annual Review of Ecology, Evolution, and Systematics 46, 523-549.
| Crossref | Google Scholar |

Hughes AC, Orr MC, Yang Q, Qiao H (2021) Effectively and accurately mapping global biodiversity patterns for different regions and taxa. Global Ecology and Biogeography 30, 1375-1388.
| Crossref | Google Scholar |

iNaturalist community (2023) Observations of Skinks from Australia, observed before 21 July 2023. Available at https://www.inaturalist.org [accessed 21 July 2023]

IUCN (2023a) The IUCN red list of threatened species. Version 2022-2. Available at https://www.iucnredlist.org/en [accessed 21 October 2023]

IUCN (2023b) Spatial data for skinks of Australia. Available at https://www.iucnredlist.org [accessed 1 August 2023]

Kraus F (2009) ‘Alien reptiles and amphibians: a scientific compendium and analysis.’ (Springer Science and Business Media B.V: Dordrecht, The Netherlands) 10.1007/978-1-4020-8946-6

Lenth RV (2024) emmeans: estimated marginal means, aka least-squares means. Available at https://rvlenth.github.io/emmeans/

Lockwood JL, Welbourne DJ, Romagosa CM, Cassey P, Mandrak NE, Strecker A, Leung B, Stringham OC, Udell B, Episcopio-Sturgeon DJ, Tlusty MF, Sinclair J, Springborn MR, Pienaar EF, Rhyne AL, Keller R (2019) When pets become pests: the role of the exotic pet trade in producing invasive vertebrate animals. Frontiers in Ecology and the Environment 17, 323-330.
| Crossref | Google Scholar |

Melbourne I (2023) iNaturalist observation. Available at https://www.inaturalist.org/observations/164903461 [accessed 21 July 2023]

Mesaglio T, Callaghan CT (2021) An overview of the history, current contributions and future outlook of iNaturalist in Australia. Wildlife Research 48, 289-303.
| Crossref | Google Scholar |

Pili AN, Tingley R, van Winkel D, Maria L, Chapple DG (2023) The escalating global problem of accidental human-mediated transport of alien species: a case study using alien herpetofauna interceptions in New Zealand. Biological Conservation 278, 109860.
| Crossref | Google Scholar |

Pimm SL, Jenkins CN, Abell R, Brooks TM, Gittleman JL, Joppa LN, Raven PH, Roberts CM, Sexton JO (2014) The biodiversity of species and their rates of extinction, distribution, and protection. Science 344, 1246752.
| Crossref | Google Scholar |

QGIS Development Team (2023) QGIS geographic information system. Available at http://qgis.org

R Core Team (2023) R: a language and environment for statistical computing. Available at https://www.R-project.org/

Rabosky DL, Hutchinson MN, Donnellan SC, Talaba AL, Lovette IJ (2014) Phylogenetic disassembly of species boundaries in a widespread group of Australian skinks (Scincidae: Ctenotus). Molecular Phylogenetics and Evolution 77, 71-82.
| Crossref | Google Scholar | PubMed |

Robertson P, Coventry AJ (2019) ‘Reptiles of Victoria: a guide to identification and ecology.’ Illustrated edn. (CSIRO Publishing: Melbourne, Vic, Australia)

Roger E, Kellie D, Slatyer C, Brenton P, Torresan O, Wallis E, Zerger A (2023) Open access research infrastructures are critical for improving the accessibility and utility of citizen science: a case study of Australia’s National biodiversity infrastructure, the Atlas of Living Australia (ALA). Citizen Science: Theory and Practice 8, 56.
| Crossref | Google Scholar |

Roll U, Feldman A, Novosolov M, Allison A, Bauer AM, Bernard R, Böhm M, Castro-Herrera F, Chirio L, Collen B, Colli GR, Dabool L, Das I, Doan TM, Grismer LL, Hoogmoed M, Itescu Y, Kraus F, LeBreton M, Lewin A, Martins M, Maza E, Meirte D, Nagy ZT, de C. Nogueira C, Pauwels OSG, Pincheira-Donoso D, Powney GD, Sindaco R, Tallowin OJS, Torres-Carvajal O, Trape J-F, Vidan E, Uetz P, Wagner P, Wang Y, Orme CDL, Grenyer R, Meiri S (2017) The global distribution of tetrapods reveals a need for targeted reptile conservation. Nature Ecology & Evolution 1, 1677-1682.
| Crossref | Google Scholar | PubMed |

Rolph S (2022) iNaturalist observation. Available at https://www.inaturalist.org/observations/112137445 [accessed 21 July 2023]

Rowley JJL, Callaghan CT (2023) Tracking the spread of the eastern dwarf tree frog (Litoria fallax) in Australia using citizen science. Australian Journal of Zoology 70, 204-210.
| Crossref | Google Scholar |

Singhal S, Hoskin CJ, Couper P, Potter S, Moritz C (2018) A framework for resolving cryptic species: a case study from the lizards of the Australian wet tropics. Systematic Biology 67, 1061-1075.
| Crossref | Google Scholar | PubMed |

Sirami C, Caplat P, Popy S, Clamens A, Arlettaz R, Jiguet F, Brotons L, Martin J-L (2017) Impacts of global change on species distributions: obstacles and solutions to integrate climate and land use. Global Ecology and Biogeography 26, 385-394.
| Crossref | Google Scholar |

Sprackland R, Sprackland T, Diessner D (2004) Reptiles and mammals of Fitzroy Island, Queensland. Memoirs of the Queensland Museum 49, 733-739 Available at https://www.researchgate.net/publication/293597276_Reptiles_and_mammals_of_Fitzroy_Island_Queensland.
| Google Scholar |

Tingley R, Macdonald SL, Mitchell NJ, Woinarski JCZ, Meiri S, Bowles P, Cox NA, Shea GM, Böhm M, Chanson J, Tognelli MF, Harris J, Walke C, Harrison N, Victor S, Woods C, Amey AP, Bamford M, Catt G, Clemann N, Couper PJ, Cogger H, Cowan M, Craig MD, Dickman CR, Doughty P, Ellis R, Fenner A, Ford S, Gaikhorst G, Gillespie GR, Greenlees MJ, Hobson R, Hoskin CJ, How R, Hutchinson MN, Lloyd R, McDonald P, Melville J, Michael DR, Moritz C, Oliver PM, Peterson G, Robertson P, Sanderson C, Somaweera R, Teale R, Valentine L, Vanderduys E, Venz M, Wapstra E, Wilson S, Chapple DG (2019) Geographic and taxonomic patterns of extinction risk in Australian squamates. Biological Conservation 238, 108203.
| Crossref | Google Scholar |

Visconti P, Di Marco M, Álvarez-Romero JG, Januchowski-Hartley SR, Pressey RL, Weeks R, Rondinini C (2013) Effects of errors and gaps in spatial data sets on assessment of conservation progress. Conservation Biology 27, 1000-1010.
| Crossref | Google Scholar | PubMed |

Wickham H, Averick M, Bryan J, Chang W, McGowan LD, François R, Grolemund G, Hayes A, Henry L, Hester J, Kuhn M, Pedersen TL, Miller E, Bache SM, Müller K, Ooms J, Robinson D, Seidel DP, Spinu V, Takahashi K, Vaughan D, Wilke C, Woo K, Yutani H (2019) Welcome to the Tidyverse. Journal of Open Source Software 4, 1686.
| Crossref | Google Scholar |

Wilson S, Swan G (2021) ‘A complete guide to reptiles of Australia.’ 6th edn. (Reed New Holland)

Wotherspoon L, de Oliveira Caetano GH, Roll U, Meiri S, Pili A, Tingley R, Chapple DG (2024) Inferring the extinction risk of data deficient and not evaluated Australian squamates. Austral Ecology 49, e13485.
| Crossref | Google Scholar |