Birds in Fragmented Landscapes: Genes to Landscapes

Full project title funded under Australian Research Council Linkage grant scheme: How much habitat and what configuration maintain natural levels of connectivity in southeast Australian native birds?

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One of the study sites	Striated pardalote in the net	Jim banding a yellow-tufted honeyeater

Participants

Shandiya and Linda processing
brown treecreeper

Paul Sunnucks, Alexandra (Sasha) Pavlova, Alan Lill & Naoko Takeuchi (School of Biological Sciences, Monash U), Jim Radford (Deakin U, Bush Heritage Australia), Jane Melville (Museum Victoria), Graeme Newell & Matt White (ARI, DSE), Leo Joseph (ANWC) PhD students: Shandiya Balasubramaniam (U Melbourne with Raoul Mulder, Museum Victoria) Honours students: Linda Grootendorst (Monash U), Rebecca Bray (Museum Victoria)

Partner Organisations

Department of Sustainability & Environment, Museum Victoria, Department of Primary Industries, Parks Victoria, North-Central Catchment Management Authority, Goulburn Broken Catchment Management Authority

Supporting Organisations

Birds Australia, Australian National Wildlife Collection

Naoko measuring noisy miner

Natural levels of movement of individuals are critical for maintaining populations in fragmented systems. Movement is necessary to recolonise empty habitat, ‘rescue’ declining populations, and prevent negative genetic impacts. Thus, movement between fragments is likely to be critical for persistence in fragmented landscapes. Population viability is enhanced by natural levels of exchange of individuals and genes between sub-populations. Although rarely tested, it is assumed that movement is closely aligned with structural connectivity (eg corridors, stepping-stones). Thus, considerable emphasis has been placed on increasing structural connection to increase population persistence. However, there is scant evidence that movement is dependent on structural connectivity. A major impediment here has been the logistic constraints associated with quantifying movement using traditional ecological techniques (eg mark-recapture, radio-tracking). The advent of a variety of powerful genetic analyses means that movement can now be feasibly assessed.

Molecular information contained in the genotype provides a direct proxy for mark-recapture data but without the need for recapture. The accumulation of movement over many generations can also be resolved, to examine responses in relation to landscape change. Demographic processes and population trajectories can also be estimated. The integration of molecular data with relative abundance data from observational surveys and measures of landscape structure from GIS analyses (ie ‘landscape genetics’) generates a powerful toolkit for evaluating population-level responses to landscape change.

	This project examines the relationship between movement of individuals, landscape structure (amount and arrangement of native vegetation) and population size, for selected bird species, building on the major landscape-scale innovative research of Radford et al. (2005) & Radford and Bennett (2007), who demonstrated that many species decrease in abundance with decrease of the size of the remaining remnants (‘decliners’) but some maintain or even increase their population density in small remnants in fragmented landscapes (‘resistant’). A fundamental difference between ‘resistant’ species and ‘decliners’ may be their ability to move through fragmented landscapes.
Shandiya releasing eastern yellow robin		Alan releasing by-catch (brown falcon)

We are employing a novel research approach that couples existing data on the incidence of bird species in landscapes with molecular techniques that quantify the extent of ‘within-landscape’ and ‘between-landscape’ movement, and population trends, or ‘trajectories’. Thus, we will assemble a unique dataset that contains information on current population size (survey data), extent of movement at several spatial and temporal scales (molecular data) and population trajectories (molecular data) for selected species in landscapes that vary in the amount and pattern of native vegetation. Our objectives are to quantify the movement and other population processes of selected bird species within and among landscapes, which will enable us to identify landscape features that promote natural population functions at patch, landscape and bioregional scales, and to compare population function and trajectories among species that have contrasting responses to landscape-level habitat loss.


Sasha extracting brown treecreeper from the net	Alan taking a blood sample	Naoko giving a yellow-tufted honeyeater a drink

Field work

The fieldwork will last 2.5 years from November 2007 to March 2010 and include mist-netting and banding birds, taking morphological measurements and collecting small blood and feather samples for genetic analyses and tests of bird health. Our ten study “landscapes” are situated in the beautiful box-ironbark forests of central Victoria. Target species include ‘decliners’ Brown Treecreeper, Fuscus Honeyeater, Yellow-tufted Honeyeater, Superb Fairy-wren, Brown-headed Honeyeater, Grey Shrike-thrush, Eastern Yellow Robin, and ‘resistant species’ White-plumed Honeyeater, Striated Pardalote, Weebill, White-winged Chough and Noisy Miner.

Landscape Genetic analyses

Nuclear microsatellite markers will be used for genotyping all sampled individuals. Some of the markers developed for other species of birds are effective in our target species. Analyses of genotypes will allow us to explore population structure and patterns of dispersal within and between landscapes. Using a small sample of DNA from blood or feather tissue, the sex of the individual birds can be identified.


Microsatellite HrU2 run on licor gel	sexing PCR run on agarose gel	Sasha extracting DNA from blood

DNA extractions from feathers while in the field - just need boiling water and a pre-mixed tube of reagents

This is particularly useful for honeyeaters and other species that are difficult to sex in the hand. This information will be used to explore patterns of sex-biased dispersal. Integrated data on landscape genetics will result in formulation of policy-informing documents. Apart from these mainstream questions other exceptionally important issues that have potential to impact population persistence and the nature of human-impacted populations will be explored. Here are some examples:

Kin associations and social structures: does level of relatedness within patch increase with level of fragmentation?
Mating systems, parentage and extra-pair paternity in fragmented landscapes.
The long-term effect of human-induced habitat fragmentation.
Impact of habitat fragmentation on level of chronic stress in bird populations.
The interplay between immune system genes and stress levels.
Contrasting stress level and acoustic activity: does habitat fragmentation induces stress and impairs aspects of reproductive performance in birds?
Breeding biology: how do birds search for breeding areas at the landscape level?
Population viability modelling: integration of spatially-explicit distribution data from surveys and genetically-derived parameters of pop growth and dispersal capabilities.

Join in!

If you love birds, enjoy working in a bush and would like to help us in the field please e-mail Sasha or Naoko on your availability. The project privides meals and accomodation to field volunteers. We are looking forward to sharing hard but fun and rewarding fieldwork with you!


Yellow-tufted Honeyeater ©Chris Tzaros/Birds Australia	Superb Fairy-Wren ©Chris Tzaros/Birds Australia	White-plumed Honeyeater ©Chris Tzaros/Birds Australia	Grey Shrike-thrush ©Chris Tzaros/Birds Australia

Citations

Radford, J.Q., Bennett, A.F., Cheers, G.J., 2005. Landscape-level thresholds of habitat cover for woodland-dependent birds. Biol Conserv 124, 317-337.
Radford, J.Q., Bennett, A.F., 2007. The relative importance of landscape properties for woodland birds in agricultural environments. J Appl Ecol 44, 737-747.