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BushfireConf2017 – 23. Fire, feral and native animal interactions: perspectives from central Australia.
- 1. Fire, feral and native animal interactions: perspectives from central Australia Chris Dickman, Aaron Greenville and Glenda Wardle
- 2. Aims • Describe population fluctuations of rodents and small marsupials in Australian desert (‘boom’ and ‘bust’) environments: pulses of food, pulses of fear? • Explore patterns and processes: • Effects of rainfall on populations • Effects of fire • Rainfall × fire × feral predator interactions • How to manage these interactions for conservation goals; effects of climate change
- 3. Arid Australia Hummock (spinifex) grassland Simpson Desert
- 4. Simpson Desert study region • NE Simpson Desert, Qld • Spinifex-dominated dunefields • Rainfall 150 – 200 mm year-1 • Temperatures -7 to >50°C • Fire return interval: was ~25 years, now 10 – 12 years • Long-term data 1990- present • > 28,000 mammal captures, ~24,000 lizard captures, ~10,000 frogs
- 5. Simpson Desert study region • 12 main sites over 8,000 km2 • 2–5 sampling plots / site • Small vertebrates, invertebrates, plants, weather data sampled • Many experiments • 3–6 visits / year
- 6. Simpson Desert study region 1990 – drought ‘bust’ 2012 – post rain ‘boom’
- 7. Study species + methods Photo by Bobby Tamayo Sandy inland mouse Pseudomys hermannsburgensis Ningaui Dunnart Mulgara Hopping-mouse
- 8. Boom and bust dynamics Average of Pseudomys hermannsburgensis 0 10 20 30 40 50 60 1990 1991 1993 1999 2001 2002 2006 2008 2011 Captures(100trapnights) Sandy inland mouse Average of Notomys alexis 0 10 20 30 40 50 60 1990 1991 1993 1999 2001 2002 2006 2008 2011 Captures(100trapnights) Spinifex hopping-mouse Photo by Bobby Tamayo Sandy inland mouse Pseudomys hermannsburgensis
- 9. Effects of rain 0 50 100 150 200 250 300 350 400 1990 1990 1990 1991 1991 1992 1992 1992 1993 1993 1994 1994 1995 1995 1995 1996 1996 1997 1997 1997 1998 1998 1999 1999 2000 2000 2000 2001 2001 2002 2002 2002 2003 2003 2004 2004 2005 2005 2005 2006 2006 2007 2007 2007 2008 2008 2009 2009 2010 2010 2010 2011 2011 Rainfall(mm) Long-term annual ‘average’ rainfall Average of Pseudomys hermannsburgensis 0 10 20 30 40 50 60 1990 1991 1993 1999 2001 2002 2006 2008 2011 Captures(100trapnights) Sandy inland mouse, r = 0.66*** 6-month lag Photo by Bobby Tamayo Sandy inland mouse Pseudomys hermannsburgensis
- 10. Effects of rain Long-term annual ‘average’ rainfall 0 50 100 150 200 250 300 350 400 1990 1990 1990 1991 1991 1992 1992 1992 1993 1993 1994 1994 1995 1995 1995 1996 1996 1997 1997 1997 1998 1998 1999 1999 2000 2000 2000 2001 2001 2002 2002 2002 2003 2003 2004 2004 2005 2005 2005 2006 2006 2007 2007 2007 2008 2008 2009 2009 2010 2010 2010 2011 2011 Rainfall(mm) Average of Dasycercus cristicauda 0 0.5 1 1.5 2 2.5 3 3.5 4 4.5 5 1990 1991 1993 1999 2001 2002 2006 2008 2011 Captures(100trapnights) Long-term annual ‘average’ rainfall Brush-tailed mulgara, r = 0.58*** 10-month lag
- 11. Effects of rain 0 50 100 150 200 250 300 350 400 1990 1990 1990 1991 1991 1992 1992 1992 1993 1993 1994 1994 1995 1995 1995 1996 1996 1997 1997 1997 1998 1998 1999 1999 2000 2000 2000 2001 2001 2002 2002 2002 2003 2003 2004 2004 2005 2005 2005 2006 2006 2007 2007 2007 2008 2008 2009 2009 2010 2010 2010 2011 2011 Rainfall(mm) Long-term annual ‘average’ rainfall Average of Sminthopsis youngsoni 0 1 2 3 4 5 6 7 8 1990 1991 1993 1999 2001 2002 2006 2008 2011 Captures(100trapnights) Lesser hairy-footed dunnart, r = -0.33** 2-6 month lag
- 12. Wildfire follows rain Annual rainfall (mm) for years 1913 - 2001/02 0 100 200 300 400 500 600 700 800 1910 1930 1950 1970 1990 2010 Marion Downs Glenormiston Fire 1917 Fire 2001 Fire 1951 Fire 1974
- 13. Wildfire: Simpson Desert • Wildfire in 2001- 02 burnt 254,400 ha of study area, mostly spinifex, some woodland • Elsewhere, ~3 million ha burnt • Wildfire in 2011 burnt >25,000 ha of study area • Mean fire return interval = 25 years; declining
- 15. Effects of wildfire: spinifex cover 0 5 10 15 20 25 30 35 40 45 50 Apr.00 Jun.00 Aug.00 Oct.00 Nov.00 Mar.01 Apr.01 Jun.01 Sep.01 Dec.01 Feb.02 Mar.02 Apr.02 May.02 Jun.02 Jul.02 Aug.02 Sep.02 Oct.02 Nov.02 Dec.02 Feb.03 May.03 Jun.03 Dec.03 Feb.04 May.04 Aug.04 Nov.04 Feb.05 Apr/May.05 Aug.05 O/N/D.05 Feb.06 May.06 Aug/Sept.06 Nov.06 2000 2001 2002 2003 2004 2005 2006 Mean%SpinifexCoverpergrid Spinifex cover Burnt Unburnt Wildfire
- 16. Effects of wildfire: small mammal nos Small mammal abundance 0 2 4 6 8 10 12 14 Apr.00 Jun.00 Aug.00 Oct.00 Nov.00 Apr.01 Jun.01 Sept.01 Dec.01 Feb.02 Mar.02 May.02 Jul.02 Aug.02 Sept.02 Oct.02 Nov.02 Dec.02 Feb.03 May.03 Jun.03 Dec.03 May.04 Aug.04 Nov.04 Feb.05 Apr/May.05 Aug.05 O/N/D.05 Feb.06 May.06 Aug/Sep.06 Nov.06 2000 2001 2002 2003 2004 2005 2006 Meancapturespergridnight Burnt UnburntWildfire
- 17. Introduced predators 0 5 10 15 20 25 30 35 40 1990 1991 1993 1996 1999 2000 2002 2003 2005 2007 2008 2009 Sighting/100km Feral cat Red fox Red fox
- 18. Introduced predators and prey 0 5 10 15 20 25 30 35 40 1990 1991 1993 1996 1999 2000 2002 2003 2005 2007 2008 2009 Sighting/100km Feral cat Red fox Average of Pseudomys hermannsburgensis 0 10 20 30 40 50 60 1990 1991 1993 1999 2001 2002 2006 2008 2011 Captures(100trapnights) Feral cat Red fox Capture rate: Sandy inland mouse
- 19. Predator diets: foxes and cats Time period / population phase of mammal prey % frequency of small mammals in diet of: Fox, n = 1245 Cat, n = 743 Bust 24 – 66% 45 – 82% Increase 50 – 87% 73 – 95% Peak 98 – 100% 100% Decrease 95 – 100% 98 – 100%
- 20. Predator impacts Average of Pseudomys hermannsburgensis 0 10 20 30 40 50 60 1990 1991 1993 1999 2001 2002 2006 2008 2011 Captures(100trapnights) Capture rate: Sandy inland mouse Heavy summer rains Intense per capita predation Rains Predation
- 21. Wildfire × predator interactionsTransectswithprints Feral cats Red foxes Transects Unburnt Burnt EcEcotone
- 22. Wildfire × predator interactions • Experiment: GUD dishes set in burnt (open) and unburnt (spinifex-covered) habitats • Three treatments: under fox and cat-proof fencing (n = 7), under open fencing (fence control, n = 7), and in open sand (n = 7) • 20 seeds / night provided for rodents Giving-up densities (GUDs)
- 23. Wildfire × predator interactionsGiving-updensity Exclusion cage Cage control Open control Sandy inland mouse, predation × fire, F = 16.15*** Spinifex hopping-mouse, predation × fire, F = 9.81*** Burnt Unburnt
- 24. Wildfire × predator interactions Scaling up: 250 m2 of predator-free shelter per 1-ha plot
- 25. Annual rainfall – last 100 years
- 26. Conclusions • Rainfall: Increases productivity, increases populations of rodents and other consumers • Wildfire: natural, lightning ignition, follows heavy rain events; decreases animal populations • Invasive predators: reduce prey by direct consumption • These factors interact: heavy rains increase rodents, risk of fire and numerical response by predators; the fire × predation interaction drives mammal populations to low levels; predation, webs of fear come and go in pulses • Climate change will exacerbate boom-bust cycles and wildfires; irruptive rodent species will be at most risk, and then carnivorous marsupials • Management: strategic (time, place) reduction of invasive predators, or increased protection for vulnerable prey – is there a broader role for predator- proof shelters in fire-prone landscapes?
- 27. Acknowledgements • TERN and LTERN • Desert Ecology Research Group, esp. Bobby Tamayo, Chin-Liang Beh • > 1000 volunteers + students • Bedourie community • Bush Heritage Australia • Australian Research Council