Tim Cutajar

Tim Cutajar

PhD Student
Centre for Ecosystem Science
Biological, Earth & Environmental Sciences

I am a PhD candidate at UNSW Sydney, the Australian Museum, and the University of Copenhagen. My primary research interest is in creative techniques of improving the detectability of rare and elusive species.

Recently I developed a method of surveying frog species that are difficult to detect, using invertebrate-derived DNA (iDNA). The principle behind iDNA is that while some animals are very elusive, parasites tend to be everywhere. We can collect parasites, barcode the DNA in their bellies, and ‘detect’ their host animal without having to see it first-hand! I tested this for amphibians by broadcasting frog calls in the forest. The sound of those calls attracted frog-biting, blood-sucking flies, which flew en masse right into traps next to my speakers. Some of these flies had bellies full of frog blood, so I extracted and sequenced the DNA from that blood. Through these flies I detected threatened frogs that were missed during traditional surveys at most sites, including one species that we never saw or heard at all!

Establishing iDNA with frog-biting flies as a promising survey method for frogs is just the beginning. My small pilot study raised even more questions: Just how effective is it compared to other methods? How does its effectiveness vary across species or space? What makes a frog species a good candidate for iDNA surveys? And how can detection success through iDNA be improved? These are the questions that drive my research, and I’m passionate about developing iDNA and other DNA-based survey techniques as powerful tools in providing those invaluable species observations that help us understand where species live, how they’re doing, and what their conservation needs are.

Project: Can bugs do it better? Determining the utility of invertebrate-derived DNA for species detectability in amphibian communities and improving survey designs

Supervised by: Jodi Rowley, Kristine Bohmann, and Alistair Poore

Project Description: The broadest aim of my project is to improve the detectability of vertebrate species for better informed biodiversity conservation. To do this, I am collecting and analysing environmental DNA (eDNA: DNA shed by organisms in to their environment) from water, parasites, and even air. The three techniques are in various stages of development and all show promise, but their relative efficacies and biases have not been assessed, leaving researchers and wildlife managers potentially uninformed of the best techniques to which limited resources should be allocated. Through this work I am determining which eDNA techniques would be best utilised for which vertebrate taxa and ecological guilds. By performing this work in the known or historic ranges of poorly-known and 'lost' species, I hope to provide much-needed new information of their populations.

I am also focussing iDNA - eDNA derived from parasitic (or scavenging) invertebrates. In particular, I am unravelling the relationship between frogs and blood-sucking, frog-biting flies, which are an excellent source of DNA (and thus detections) of elusive frog species. Very little is known about which frog species are most parasitised by frog biting flies and what makes them likely hosts. My iDNA-specific research aims to determine this, both to inform future frog surveys in terms of target species selection, and to inform developments to frog-biting fly collection techniques for increased fly yields and thus frog species detections.

Contact Details


Cutajar, T. and Pulsford, S. (2023) Incidental invertebrate‐derived DNA detection of invasive and threatened species in temperate dry Southeast Australian forest. Austral Ecology. online early.

Mahony, S., Cutajar, T. and Rowley, J.J.L. (2022) A new species of Delma Gray 1831 (Squamata: Pygopodidae) from the Hunter Valley and Liverpool Plains of New South Wales. Zootaxa. 5162: 541-556.

Cutajar, T., Portway, C. and Rowley, J.J.L. (2022) Australian Frog Atlas: Species distribution maps informed by the FrogID dataset. Technical Reports of the Australian Museum Online. 36: 1-48.

Tapley, B., Nguyen, L.T., Nguyen, C.T., Hoang, G.T. & Cutajar, T. (2021) Oviposition sites of the Hoang Lien Horned Frog, Megophrys hoanglienensis (Tapley et al., 2018). Herpetology Notes. 14: 937-939.

Tapley, B., Cutajar, T., Nguyen. L.T., Portway, C., Mahony, S., Nguyen, C.T., Harding, L., Luong, H.V., & Rowley, J.J.L. (2021). A new potentially Endangered species of Megophrys from Mount Ky Quan San, northwest Vietnam. Journal of Natural History. 54: 2543-2575.

Alabai, M., Esau, T., Kekeubata, E., Esau, D., Waneagea, J., Lobotalau, L., Alick, J., Silas, J., Solome, L., Waneagea, J., Mousisi, K., Cutajar, T., Portway, C.D., MacLaren, D.J., & Rowley, J.J.L. (2020). Apparent absence of the amphibian chytrid fungus (Batrachochytrium dendrobatidis) in frogs in Malaita Province, Solomon Islands. Pacific Conservation Biology.

Nguyen, L. T., Tapley, B., Cutajar, T., Nguyen, C.T., Portway, C., Harding, L., Luong, H.V. & Rowley, J.J.L. (2020). A description of the tadpole of the Critically Endangered Botsford’s leaf-litter frog (Leptobrachella botsfordi) with comments on the distribution and conservation status of the species. Zootaxa. 4860: 293–300.

Tapley, B., Nguyen, L.T., Cutajar, T., Nguyen, C.T., Portway, C., Van Luong, H., and Rowley, J.J.L. (2020). The tadpoles of five Megophrys Horned frogs (Amphibia: Megophryidae) from the Hoang Lien Range, Vietnam. Zootaxa, 4845 (1): 35–52.

Tapley, B., Nguyen, L.T., Portway, C., Cutajar, T., Nguyen, C.T., Van Luong, H., Kane, D., Harding, L. & Rowley, J.J.L. (2020) A point endemic no more; a range extension for Oreolalax sterlingae (Nguyen et al., 2013) in Bat Xat District, Lao Cai Province, northern Vietnam. Herpetology Notes. 13, 497-500.

Portway, C.D., Cutajar, T., King, A. & Rowley, J.J.L. (2020) First evidence of the amphibian chytrid fungus likely driving dramatic frog community changes on the New England Tablelands of Eastern Australia. Herpetological Review. 51 (2), 247-251.

Portway, C.D., Cutajar, T. & Rowley, J.J.L. (2020) Survey for amphibian chytrid fungus infection in the enigmatic Green-thighed Frog (Litoria brevipalmata). Herpetological Review. 51 (2), 252-253.
Cutajar, T. and Rowley, J.J.L. (2020) Surveying frogs from the bellies of their parasites: invertebrate-derived DNA as a novel survey method for frogs. Global Ecology & Conservation. e00978.

Cutajar, T., Rowley, J.J.L., Nguyen, L.T., Nguyen, C.T., Portway, C., Harding, L., Luong, H.V. and Tapley, B. (2020) The advertisement call of Megophrys jingdongensis Fei and Ye, 1983 and a new record from Lai Chau Province, Northeast Vietnam. Herpetology Notes. 13: 139-143.

Nguyen, L.T., Tapley, B., Cutajar, T., Nguyen, C.T., Portway, C., Harding, L., Van Luong, H. and Rowley, J.J.L. (2019) The first records of Limnonectes nguyenorum Mcleod, Kurlbaum & Hoang (Amphibia: Anura: Dicroglossidae) from lao Cai Province, northwest Vietnam. Proceedings of the 4th National Scientific Conference on Amphibians and Reptiles in Vietnam.

Rowley, J.J., Callaghan, C.T., Cutajar, T., Portway, C., Potter, K., Mahony, S., Trembath, D.F., Flemons, P. & Woods, A. (2019) FrogID: Citizen Scientists provide validated biodiversity data on frogs of Australia. Herpetological Conservation and Biology. 14 (1): 155-170.

For full list see timcutajar.com