Australian waterbirds: genetics, movement patterns and conservation

A project undertaken at the Australian National Wildlife Collection, CSIRO Ecosystems Sciences, and supervised by Dr Terry Chesser (2002 - 2004) and Dr Leo Joseph (2005 onwards)

Australia's wetlands systems are a fascinating product of the continent's climatic variability and irregular rainfall patterns. Australia's waterbirds, in turn, have responded to this environmental unpredictability, and our distinctive climate and ephemeral wetlands have produced a behaviourally unique waterbird fauna. Whereas north temperate zone waterbirds respond to regular seasonal factors – migrating, breeding, and moulting at the same time every year, and using the same habitat again and again – Australia's waterbirds undergo boom and bust cycles of population numbers, congregating and breeding in dense concentrations during large rainfall events and then surviving the leaner times. Thus, although it isn't as immediately noticeable, Australian waterbirds are every bit as distinctive as our native marsupials and other uniquely Australian natural features.

The Australia National Wildlife Collection (ANWC) is using genetic data to provide insight into a number of fundamental issues and questions relating to Australian waterbirds. These include:

  • Where do the congregating waterbirds come from?
  • How far do they move?
  • Do species move primarily within circumscribed geographic regions?
  • Or do waterbird populations effectively range across all of Australia?
  • Do different species differ in their movement patterns?
  • If so, how?
  • Is this correlated with other features?

Some 85 species of waterbirds breed in Australia, and more than 40 other species over-winter in the country. These include Anseriformes (duck, geese, swans), Podicipediformes (grebes), Pelecaniformes (pelicans and cormorants, among others), Ciconiiformes (herons, ibis, storks), Gruiformes (rails, coots, cranes), and Charadriiformes (waders, gulls, terns). We are particularly interested in breeding species that are found exclusively or extensively in freshwater habitats, which number about 77 species.

One of the difficulties in working with waterbirds is that field researchers, even those using radio-tracking, are limited in time and space – and this is an especially important consideration when dealing with an unpredictable and variable system. Genetics, in contrast, offers us the potential to look at waterbird movements across broad expanses of time and space, and provide a long-term, continent-wide view of patterns of gene flow and dispersal in Australian waterbirds. The patterns of past movements of waterbird populations, as well as vital information for biodiversity conservation, are present in the genes of individual birds. Continent-wide genetic sampling of individual species will reveal the extent of their movements over long periods of time across their entire range, and demonstrate the number and geographical distribution of conservation-worthy populations of the species.

Genetic studies to date have highlighted some remarkable findings. Perhaps foremost has been the extraordinary result that two flocks of Wandering Whistling-Ducks on Cape York Peninsula were genetically very distinct from each other despite having been sampled within a few days and kilometres of each other.  One flock had closer affinity to birds sampled in Papua New Guinea. The foundation has been laid for closer study of how northern Australian waterbird populations of a given species are connected geographically and seasonally to their counterparts on the other side of Torres Strait on the island of New Guinea. The research has also clarified the nature of genetic differences between eastern and western populations of Chestnut Teal.

Knowledge of waterbird population dispersal and movement patterns can also be of immense benefit to epidemiologists in tracking the spread of animal-borne pathogens. More informed knowledge of waterbird movements will assist health authorities in similar investigations, especially in an era of possible influx of exotic diseases such as avian flu to Australia.

Publications

Joseph, L., Adcock, G. J., Linde, C., Omland, K. E., Heinsohn, R., Chesser, R. T. and Roshier, D. (2009). A tangled tale of two teal: population history of the grey Anas gracilis and chestnut teal A. castanea of Australia. J Avian Biol. 40, 430 - 439.

Roshier, D. A., Heinsohn, R., Adcock, G. J., Beerli, P. and Joseph, L. (2012). Biogeographic models of gene flow in two waterfowl of the Australo-Papuan tropics. Ecology and Evolution. 2, 2803 - 2814. doi: 10. 1002/ece3.393

Dhami, K. K., Joseph, L., Roshier, D. A., Heinsohn, R. and Peters, J. L. (In press, February 2013). Multilocus phylogeography of Australian teals (Anas spp.): a case study of the relationship between vagility and genetic structure. J. Avian Biol. doi: 10.1111/j.1600-048X.2012.05826.x

 
Straw-necked Ibis

Grey Teal

Black-winged Stilt