Overabundant kangaroos: concerns, causes and cures Graeme Coulson
School of BioSciences Macropus Consulting Types of overabundance
Abundance — Impact
1. Threaten human life or livelihood 2. Depress other favoured species 3. Too numerous for their own good 4. Above equilibrium density (Caughley 1981) Threats to humans
Threats to humans
Threats to humans
Depress other species
4000
3000
2000 Hooked
Aabundance 1000 Needlewood
0 Hattah-Kulkyne National Park 1982 1984 1986 1988 1990 Depress other species
1200 120
Kangaroos 1000 Bandicoots 100 800 80
600 60
400 40 Bandicoot captures Bandicoot
Kangaroo abundance Kangaroo 200 20
0 0 1990 1992 1994 1996 1998 Year
Eastern Woodlands Historic Park Barred Bandicoot Poor welfare Body condition Reproduction 14
50 12
40 10 8 30 6 Fat (%) Index Fat 20 4 % females breeding % females 10
Kidney 2
0 0 2007 2009 5.0 2007 2009
4.0 /ha) 3.0 roos ( 2.0
1.0 Density 0.0 Serendip Sanctuary 1996 1998 2000 2002 2004 2006 2008 2010 Year Poor welfare
Lumpy jaw 54% prevalence
Serendip Sanctuary Above equilibrium
Stabilisation
Decline
Post-decline
Increase ‘irruption’ Population density Population
Time Above equilibrium
Puckapunyal Military Area Regulation
bottom up
Serendip, May 2006 RegulationPopulation irruptions
Serendip, May 2006 Solutions?
Population density
bottom up Exclusion
Direct effect Small scale Maintenance? Defence Establishment Orchard Hills Deterrence
Different senses Relevant stimuli? Desirable response? Habituation? Fertility control
Indirect effect Long-acting? Delivery? Marking? Predators
Large scale Direct effect Indirect effect Unintended effects? Wilsons Promontory National Park Culling
Direct effect Last resort Humane? Managing overabundance
• Overabundance has multiple effects • Irruptions seem to be inevitable • Early actions are essential
Population density Thank you
Australasian Wildlife Management Society Dept. of Environment, Land, Water & Planning Dept. of Zoology, University of Melbourne Independent Panel of Experts Kangaroo Advisory Group, ANGAIR Kangaroo Technical Advisory Committee Koala and Kangaroo Contraception Program Parks Victoria Territory and Municipal Services Zoos Victoria