Dr. John G Ewen
- 2004-present: Research Fellow, Institute of Zoology.
- 2002-2004: Postdoctoral Research Fellow, Université Pierre et Marie Currie, Paris.
- 1998-2002: PhD Zoology, La Trobe University, Australia.
- 1995-1998: MSc Ecology, Massey University, New Zealand.
My research aims to improve the success of reintroduction management of the threatened and endemic New Zealand hihi and to understand more about this birds unique and sometimes bizarre ecology.
Please find more detail about the hihi project at my research group's website: http://www.hihiconservation.com
Hihi / Stitchbird Conservation and Reintroduction Biology
I work at the interface between the varied scientific disciplines which together make the scientific tool kit required for improved reintroduction management. The umbrella field is the growing discipline of reintroduction biology. Reintroduction is a widespread technique for conservation of endangered species and one that is highly visible and has tangible outcomes. This often means reintroduction becomes a showcase for conservation and a way to generate public support and involvement. Birds are the major taxa in reintroduction projects globally, and provide excellent examples of the significant advances and failures that reintroduction practitioners have made. However, the overall success of bird reintroductions is poor. Reintroduction practice has evolved with little scientific rigour and poorly established monitoring and reporting protocols. The result is we often fail to learn from our mistakes. Reintroduction biology is increasingly addressing this and benefits from the wide scientific base reintroductions draw from. Yet this raises its own problems. Wildlife ecologists, population modelers, geneticists, animal husbandry professionals, and veterinarians all contribute expertise with sometimes conflicting goals and approaches. We need to coordinate these disciplines for more efficient and successful reintroductions in the future.
The primary focus of hihi conservation is the establishment of populations through reintroduction and their subsequent management. Hihi make an ideal model system to study many of the challenges reintroduction biology faces and you can find out much more about this project by visiting my research group's website.
Hihi behavioural ecology and carotenoid based signalling
I am a behavioural ecologist by training and have always maintained a strong interest in evolutionary processes including the study of mating systems, sex allocation and signalling (including parent – offspring interactions and sexually selected adult plumage ornamentation). Hihi are a sexually dimorphic species with extreme mating behaviours (including forced face-to-face copulations unique in the bird world) resulting in intense competition to reproduce. We continue to study these behaviours to learn more about the varied mating strategies individuals adopt, how these translate into fitness and the demographic consequences this has for hihi populations.
I also continue to develop an interest in carotenoids and their use in hihi for pigmentation and health. My research group has been investigating the possible trade-off between investing carotenoids (dietary biochemicals) in self maintenance (carotenoids act as antioxidants and are important in the immune system) versus investment in signals (male plumage pigments and nestling mouth colour) and reproduction (female investment in egg yolk).
Perhaps most interesting for me is exploring and identifying when application of evolutionary theory can inform or provide novel solutions to conservation and this continues to underpin much of my research. Again please explore my research groups website for more details.
Blood-borne parasites in the New Zealand avifauna and avifauna of the Torres Strait Islands, Australia
Biological invasions are renowned for their negative impacts on native fauna. I am investigating this issue with a focus on malarial parasites in New Zealand. My first aim is to determine the extent to which avian malaria is present in the native avifauna and whether the parasites are native or the result of introduction from exotic species. I am also investigating patterns of parasitism across host species to understand the variable threats to New Zealand’s birds.
The Torres Strait islands offer another malarial parasites – avian hosts system with likely high species diversity and prevalence (given the tropical climate and abundance of vectors). These islands sit on a major migratory flyway between Southeast Asia and Australia and we are interested in investigating the dynamics of hosts and parasites during both non-migratory and migratory seasons. Malarial parasites and their bird hosts are less well studied in the tropical regions of the world especially in Australasia. Furthermore this region of Australia is poorly studied in terms of bird ecology and movements.
My main collaborators in this work are;
Recent and Representative Publications:
Thorogood, R., Ewen, J.G. & Kilner, R. (2011) Sense and sensitivity: responsiveness to offspring signals varies with the parents' potential to breed again. Proceedings of the Royal Society of London B (doi: 10.1098/rspb.2010.2594)
Ewen, J.G., Thorogood, R. & Armstrong, D.P. (2011) Demographic consequences of adult sex ratio in a reintroduced hihi population. Journal of Animal Ecology 80: 448-455.
Brekke, P., Bennett, P.M., Santure, A.W. & Ewen, J.G. (2011) High genetic diversity in the remnant island population of hihi and the genetic consequences of re-introduction. Molecular Ecology 20: 29-45.
Richardson, K., Ewen, J.G., Armstrong, D.P. & Hauber, M.E. (2010) Sex-specific shifts in natal dispersal dynamics during establishment of a reintroduced hihi population. Behaviour 147: 1517-1532.
Brekke, P., Bennett, P.M., Wang, J., Pettorelli, N. & Ewen, J.G. (2010) Sensitive males: inbreeding depression in an endangered bird. Proceedings of the Royal Society of London B 277: 3677-3684.
Sutherland, W.J., Armstrong, D.P., Butchart, S.H.M., Earnhardt, J., Ewen, J.G., Jamieson, I., Jones, C.G., Lee, R., Newberry. P., Nichols, J.D., Parker, K.A., Sarrazin, F., Seddon, P., Shah, N. & Tatayah, V. (2010) Standards for documenting and monitoring bird reintroduction projects. Conservation Letters 3: 229-235.
Ewen, J.G., Thorogood, R., Brekke, P., Cassey, P., Karadas, F. & Armstrong, D.P. (2009) Maternally invested carotenoids compensate costly ectoparasitism in the hihi.Proceedings of the National Academy of Sciences USA 106: 12798-12802.
Ewen, J.G. & Armstrong, D.P. (2007) Strategic monitoring of reintroductions in ecological restoration programmes. Ecoscience 14: 401-409.