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 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 Management Society Dept. of Environment, Land, Water & Planning Dept. of Zoology, University of Independent Panel of Experts Kangaroo Advisory Group, ANGAIR Kangaroo Technical Advisory Committee Koala and Kangaroo Contraception Program Parks Territory and Municipal Services Zoos Victoria