New Paper! Making the most of incomplete long-term datasets: the MARSS solution

Authors: Aaron C. Greenville, Vuong Nguyen, Glenda M. Wardle and Chris R. Dickman

Published in: Australian Zoologist


Field work doesn’t always go to plan and can lead to gaps in your datasets.

Long-term field-based monitoring is essential to develop a deep understanding of how ecosystems function and to identify species at risk of decline. However, conducting field-based research poses some unique challenges due to the frequently harsh environmental conditions or extreme weather events that may be encountered. Fieldwork issues can arise from vehicle breakdowns, wildfires and heavy rainfall events, all of which can delay or even cancel data collection. In addition, long-term monitoring often requires multiple observers, which may add observation bias to estimates of measured parameters. Thus there is an increasing need to develop new statistical techniques that take advantage of the power of long time-series datasets that also are incomplete. Here we introduce researchers to multivariate autoregressive state-space (MARSS) modelling; a new statistical technique for modelling long-term time-series data. MARSS models allow users to investigate incomplete datasets caused by missing values. In contrast to traditional modelling techniques, such as generalised linear models that only estimate error from environmental stochasticity (process error), MARSS models estimate both process and observation errors. By estimating observation errors, researchers can incorporate bias from different observers and methods into population or other parameter estimates. To illustrate the MARSS technique we interrogate long-term animal and plant datasets from central Australia that contain missing values and were collected by multiple observers. We then discuss the findings from the MARSS models and their implications for management. Lastly, we provide future applications that this new technique could be used for, such as studies of animal movements and food webs.


#FieldWorkFail? Making the most of incomplete long-term datasets, TERN Newsletter, September 2018.

Reference: Greenville, A. C, Nguyen, V.,  Wardle, G. M. & Dickman, C. R. (2018). Making the most of incomplete long-term datasets: the MARSS solution. Australian Zoologist, In-Press. 

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New paper: Assessing the potential for intraguild predation among taxonomically disparate micro-carnivores

Authors: Tamara I. Potter, Aaron C. Greenville & Chris R. Dickman.

Great work by Tamara and her first paper from her Honours work!

Published in: Royal Society Open Science


Wolf spider (Lycosa spp.). Photo: T. Potter

Interspecific competition may occur when resources are limited, and is often most intense between animals in the same ecological guild. Intraguild predation (IGP) is a distinctive
form of interference competition, where a dominant predator selectively kills subordinate rivals to gain increased access to resources. However, before IGP can be identified, organisms must be confirmed as members of the same guild and occur together in space and time.

The lesser hairy-footed dunnart

Lesser-hairy footed dunnart (Sminthopsis youngsoni). Photo: T. Potter

(Sminthopsis youngsoni, Dasyuridae) is a generalist marsupial insectivore in arid Australia, but consumes wolf spiders (Lycosa spp., Lycosidae) disproportionately often relative to their availability. Here, we test the hypothesis that this disproportionate predation is a product of frequent encounter rates between the interactants due to high overlap in their diets and use of space and time. Diet and prey availability were determined using direct observations and invertebrate pitfall trapping, microhabitat use by tracking individuals of both species-groups, and temporal activity using spotlighting and camera traps. Major overlap (greater than 75% similarity) was found in diet and temporal activity, and weaker overlap in microhabitat use. Taken together, these findings suggest reasonable potential, for the first time, for competition and intraguild predation to occur between taxa as disparate as marsupials and spiders.


Potter, T., Greenville, A.C. & Dickman, C.R. (2018). Assessing the potential for intraguild predation among taxonomically disparate micro-carnivores: marsupials and arthropods. Royal Society Open Science, 5: 171872.


Marsupial species eats spiders to stop spiders eating insects, Australia’s Science Channel, May 2018.

The marsupial mouse eats its competitors (Dutch), Scientias, May 2018.

This dunnart has competition for food… so it just eats the competition, Australian Geographic, May 2018.


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New paper: Biodiversity responds to increasing climatic extremes in a biome-specific manner

Authors: Aaron C. Greenville, Emma Burns, Christopher R. Dickman, David A. Keith, David B. Lindenmayer, John W. Morgan, Dean Heinze, Ian Mansergh, Graeme R. Gillespie, Luke Einoder, Alaric Fisher, Jeremy Russell-Smith , Daniel J. Metcalfe, Peter T. Green, Ary A. Hoffmann, and Glenda M. Wardle.

Published in: Science of the Total Environment (Special edition & invited paper (23 accepted from 50 submissions) by the International Long Term Ecological Research Network).


An unprecedented rate of global environmental change is predicted for the next century. The response to this change by ecosystems around the world is highly uncertain. To address this uncertainty, it is critical to understand the potential drivers and mechanisms of change in order to develop more reliable predictions. Australia’s Long Term Ecological Research Network (LTERN) has brought together some of the longest running (10–60 years) continuous environmental monitoring programs in the southern hemisphere. Here, we compare climatic variables recorded at five LTERN plot network sites during their period of operation and place them into the context of long-term climatic trends. Then, using our unique Australian long-term datasets (total 117 survey years across four biomes), we synthesize results from a series of case studies to test two hypotheses: 1) extreme weather events for each plot network have increased over the last decade, and; 2) trends in biodiversity will be associated with recent climate change, either directly or indirectly through climate-mediated disturbance (wildfire) responses. We examined the biodiversity responses to environmental change for evidence of non-linear behavior. In line with hypothesis 1), an increase in extreme climate events occurred within the last decade for each plot network. For hypothesis 2), climate, wildfire, or both were correlated with biodiversity responses at each plot network, but there was no evidence of non-linear change. However, the influence of climate or fire was context-specific. Biodiversity responded to recent climate change either directly or indirectly as a consequence of changes in fire regimes or climate-mediated fire responses. A national long-term monitoring framework allowed us to find contrasting species abundance or community responses to climate and disturbance across four of the major biomes of Australia, highlighting the need to establish and resource long-term monitoring programs across representative ecosystem types, which are likely to show context-specific responses.


Greenville A.C., Burns, B., Dickman, C.R., Keith, D.A., Lindenmayer, D.B., Morgan, J.W.,  Heinze, D., Mansergh, I., Gillespie, G.R., Einoder, L., Fisher, A., Russell-Smith, J., Metcalfe, D.J., Green, P.T., Hoffmann, A.A., and Wardle, G.M. (2018). Biodiversity responds to increasing climatic extremes in a biome-specific manner. Science of the Total Environment 634: 382–393.


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New paper: Interactions between wildfire and drought drive population responses of mammals in coastal woodlands

Authors: Mathew S. Crowther, Ayesha I. Tulloch, Mike Letnic, Aaron C. Greenville, & Chris R. Dickman

Published in: Journal of Mammalogy (Feature article)


Fire is an ecologically important process in many habitats. Increases in the frequency and intensity of wildfires due to anthropogenic activity or future changes in the global climate are suspected to impact heavily on components of the biota in fire-dependent landscapes, but there is almost no knowledge of how changes to fire regimes interact with other stressors such as drying environments. We used live-trapping techniques to investigate the effects of wildfire and drought on the abundance of 3 species of small mammals in coastal woodland in southeastern Australia. We used a generalized linear mixed effects model design to compare 4 years of post-fire trapping results with pre-fire data on both burned and unburned sites. Numbers of all small mammal species were declining due to drought prior to an extensive wildfire. Wildfire significantly exacerbated the decline in abundance of small mammals in the year after fire. A return to wetter climatic conditions was accompanied by a recovery in small mammal numbers, which was faster in unburnt sites than burnt sites. Our results demonstrate a strong linkage between climatic conditions, fire, and mammal assemblages, and emphasize the need for long-term research to disentangle the interactive effects of these factors on wildlife.


Crowther, M.S, Tulloch, A.I., Letnic, M., Greenville, A.C., & Dickman, C.R. (2018). Interactions between wildfire and drought drive population responses of mammals in coastal woodlands. Journal of Mammalogy,

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Book review: The Biology of Deserts

David Ward, 2nd edition. Oxford University Press, Oxford, 2016. xv + 370 pp.

First published in Austral Ecology.

Contrary to the popular perception that deserts are wastelands, they house some of the most diverse communities of flora and fauna of any environment on the planet. Thus, deserts provide biologists and ecologists an ideal setting to explore and test many ecological, behavioural, ecophysiological and evolutionary theories. Or as Professor
David Ward writes, we can view ‘deserts as laboratories of nature, where natural selection is exposed at its most extreme’. The Biology of Deserts provides a significant summary of the abiotic and biotic processes, which operate in arid environments, and represents one of the few general texts on desert biology (also see Whitford 2002).

Read the full review here.



Whitford W. (2002). Ecology of Desert Systems. Academic Press, San Diego.

Greenville A.C. (2017). The Biology of Deserts – David Ward , 2nd edition. Austral Ecology, DOI: 10.1111/aec.12523

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New book: Lake Eyre basin rivers: environmental, social and economic importance.

Lake Eyre Basin Rivers outlines the environmental, social and economic values of the rivers from a diverse range of perspectives, including science, tourism, economy, engineering, policy, Traditional Owners and pastoralists. It describes the current state of the environment and the past and ongoing threats to the river systems, drawing on stories from the Murray-Darling Basin. It also provides direction for ensuring that the rivers remain free-flowing to service the environment and future generations.

I had the opportunity to contribute to one of the chapters.

Chapter 6: Developing the desert: potential effects on wildlife.

In this chapter we discuss the potential consequences of irrigation and mining developments on wildlife in arid Australia.


Dickman C. R., Greenville A. C. & Wardle G. M. (2017) Developing the desert: potential effects on wildlife. In: Lake Eyre Basin rivers: environmental, social and economic importance. (ed R. T. Kingsford) pp. 63-74. CSIRO Publishing, Melbourne.

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New paper: Desert mammal populations are limited by introduced predators rather than future climate change

Authors: Aaron C. Greenville, Glenda M. Wardle & Chris R. Dickman

Published in: Royal Society Open Science


Feral cat shows off the native mouse it caught to our remote camera trap in the Simpson Desert, Queensland.

Climate change is predicted to place up to one in six species at risk of extinction in coming decades, but extinction probability is likely to be influenced further by biotic interactions such as predation. We use structural equation modelling to integrate results from remote camera trapping and long-term (17–22 years) regional-scale (8000 km²) datasets on vegetation and small vertebrates (>38 880 captures) to explore how biotic processes and two key abiotic drivers influence the structure of a diverse assemblage of desert biota in central Australia. We use our models to predict how changes in rainfall and wildfire are likely to influence the cover and productivity of the dominant vegetation and the impacts of predators on their primary rodent prey over a 100-year timeframe. Our results show that, while vegetation cover may decline due to climate change, the strongest negative effect on prey populations in this desert system is top-down suppression from introduced predators.


Greenville A.C., Wardle G. M. & Dickman C. R. (2017). Desert mammal populations are limited by introduced predators rather than future climate change. Royal Society Open Science, 4: 170384.

Further reading:

My PhD journey comes to an end: the role of ecological interactions

Of mice and dogs

Greenville A. C., Wardle G. M., Dickman Christopher R. (2012). Extreme climatic events drive mammal irruptions: regression analysis of 100-year trends in desert rainfall and temperature. Ecology and Evolution, 2, 2645-2658.

Greenville A. C., Dickman C. R., Wardle G. M. & Letnic M. (2009). The fire history of an arid grassland: the influence of antecedent rainfall and ENSO. International Journal of Wildland Fire, 18, 631-639.

Top Dog: How Dingoes Save Native Animals. Australasian Science, November 2014.


10 best Sydney science discoveries 2017, University of Sydney Media, December, 2017.

Feral animals worse than climate change, Country Today, November 2017.

Feral foxes and felines more dangerous to our desert dwellers than climate change. Scimex, November, 2017.

Feral cats, foxes a greater threat in Outback than climate change. University of Sydney Media, November, 2017.

Feral foxes, desert cats pose more threat to Aussie animals than climate change: expert. Xinhua (China), November, 2017.

Feral animals pose major threat to Outback, climate change study finds. Jersey Tribune, November, 2017.

Feral animals pose major threat to Outback, climate change study finds., November, 2017.

Feral animals pose major threat to Outback, climate change study finds. EurekAlert!, November, 2017.

Cats, foxes pose bigger risk to native wildlife than climate change in the outback. ABC News, November, 2017.

702 ABC Radio Sydney, November 2017 (at 47 min).

Füchse und Katzen schlimmer als Klimawandel?  (Germany), November, 2017.

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