Editor's Choice: Facing up to climate change at the edge of the world - new hope for the hihi

December 2013 (Issue 50:6)

Chauvenet, A. L. M., Ewen, J. G., Armstrong, D., Pettorelli, N. (2013), Saving the hihi under climate change: a case for assisted colonization. Journal of Applied Ecology. doi: 10.1111/1365-2664.12150

Quite literally at the edge of the world, in a few extremities of North Island, New Zealand, we find a rare honeyeater-like endemic called the hihi Notiomystis cincta. With its ‘tzit tzit’ call giving it its other name, the stitchbird, this beautiful little bird is fighting for its life. Emblematic of the consequences of pressures from invasive species such as black rats Rattus rattus and introduced diseases, the hihi was driven to near-extinction in the 1880s, with only a tiny remnant population surviving on Little Barrier Island. But following sterling work by conservation bodies, birds were translocated to a network of offshore reserves, which were protected from invasives, to establish new populations (e.g. Ewen et al. 2006, Driskell et al. 2007, HiHi Conservation 2013).

Now, in a new chapter for this hardy bird, we find a confrontation with climate change as the hihi’s habitat shifts southwards. How fortunate then that some quite brilliant research and conservation work is coming to the rescue. As part of this pioneering work, Chauvenet et al. (2013) have devised a means of systematically supporting the colonisation of the hihi into areas which will, climatically, sustain the birds. Remarkably, such is the nature of climate change impacts on suitable habitat that the research is pointing to the need to translocate the birds into areas that were not part of their historical range, but which will become suitable.

In support of this effort, the new IUCN guidelines on reintroductions and conservation translocations (IUCN/SSC 2103) are perfectly timed. These guide and support conservation translocations, though they explicitly reference the fact that there are virtually no examples of assisted colonisation – deliberately moving plants or animals to areas outwith their previous range where conditions are predicted to be more suitable. As the recent review by Hobbs et al. (2013) sets out clearly, we need to think about how we will, and can, respond to novel ecosystems emerging in response to climate and other changes. Having the foresight to think beyond existing ranges to the art of possibilities for new ranges is crucially important for conservation science and management.

Currently, the Department of Conservation of New Zealand is putting in place a two-pronged recovery programme for hihis: intense management of current translocated populations and establishment of new populations through translocation. And that is where the work by Chauvenet et al. (2013) is so critical, for it elegantly sets out a rigorous methodological framework for identifying translocation sites. By combining empirical work on the birds with robust statistical and predictive modelling we see how assisted colonisation could be the adaptation tool for a species threatened by climate change.

The research team has developed a penetrating understanding of the relationship between climate and population dynamics so as to make recommendations about where hihis can be translocated in the future, with assisted colonisation to South Island an option. Of course, assisted colonisations are controversial, for these are essentially introducing a species beyond its former range into new areas with all the associated risks this entails. But that is where the research on the hihi is so clever, because Chauvenet et al. (2013) have set out clear steps to guide work needed. First, they looked at how climate influences vital population parameters (age-specific survival during breeding and non-breeding seasons, and breeding success). Then, they modelled how climate change would impact on population dynamics, using a stochastic matrix model to project how the survival and breeding success of birds varied with climate. And finally, they modelled how the spatial distribution of the hihi’s habitat would be influenced by climate change. Looking ahead, the research team show how the range of the hihi may change until 2100, when there could well be established populations on South Island. They point out that one of the key limitations of their approach is reliance on habitat suitability models, which is a common concern for this type of work (e.g. Norberg et al. 2012). However, even on this front the team finds strong concurrence between the models’ results and predictive population modelling.

At the heart of this work is an excellent understanding of the ecology of the hihi and its habitat. No wonder the paper closes with the following advice: ‘We thus encourage managers to consider targeted monitoring of populations first, in order to maximize the robustness of any habitat suitability modelling.’ This is an excellent study. And what a thought - on the tiny Tiritiri Matangi Island, where hihis have been provided with supplementary food over the last 17 years to help them survive - we now have a globally significant research study which will hopefully help save one special bird, and also set the standard for many more. New Zealand’s Department of Conservation’s responsibilities are captured in its Māori name ‘Te Papa Atawhai’. Te papa signifies a box or container (for taonga/treasures) and atawhai is the act of caring, nurturing or preserving. The hihi will, in time, be synonymous with preserving nature in the novel world shaped by climate change.

Des B. A. Thompson
Associate Editor, Journal of Applied Ecology

References

Chauvenet, A. L. M., Ewen, J. G., Armstrong, D., Pettorelli, N. (2013), Saving the hihi under climate change: a case for assisted colonization. Journal of Applied Ecology. doi: 10.1111/1365-2664.12150

Driskell, A.C., Christidis, L., Gill, B., Boles, W.E., Barker, F.K., and Longmore, N.W. (2007) A new endemic family of New Zealand passerine birds: adding heat to a biodiversity hotspot. Australian J. Zoology 55 1-6

Ewen, J.G., Flux, I., and Ericson, P.G.P. (2006) Systematic affinities of two enigmatic New Zealand passerines of high conservation priority, the hihi or stitchbird Notiomystis cincta and the kokako Callaeas cinerea. Molecular Phylogenetics and Evolution 40 281-284 doi:10.1016/j.ympev.2006.01.026 PDF fulltext Accessed 8 November 2013.

HiHi Conservation (2013). The online resource for HiHi research and conservation. http://www.hihiconservation.com/ Accessed 8 November 2013.

Hobbs, R.J, Higgs, E.S and Hall, C.M. (eds) (2013). Novel Ecosytems. Intervening in the New Ecological World Order. Wiley-Blackwell, Chichester, UK.

IUCN/SSC (2013). Guidelines for Reintroductions and Other Conservation
Translocations. Version 1.0. Gland, Switzerland: IUCN Species Survival Commission. http://data.iucn.org/dbtw-wpd/edocs/2013-009.pdf Accessed 8 November 2013.

Norberg, J., Urban, M.C., Vellend, M., Klausmeier, C.A. & Loeuille, N. (2012) Eco-evolutionary responses of biodiversity to climate change. Nature Climate Change, 2, 747–751.

 

 

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