Rabbit Population Impact Calculator

Control Work Inputs

Rabbits removed

Estimated % does

Month of removal

Projection period

Net Model: Mortality Rates

Kitten mortality (to breeding age)

NSW DPI baseline: 80%, "up to 80% die before 3 months"

Adult annual mortality

Moriarty et al. 2000, central-western NSW: ~65% baseline (predation-driven, excludes the episodic RHD component); slide to 82% for the full observed rate including an RHD outbreak year.

The shaded band on the chart shows ±5% from your selected rates.

Net range (±5%)

Pasture impact (net)

Annual feed (net, dry matter)

Prevented Population Over Time

Interpreting subsequent generations: The shaded band widens over time because small differences in survival rates compound with each generation. The further out the projection, the wider the plausible range, so treat later generations as indicative rather than precise.

Estimate the population growth prevented by feral rabbit control work. Based on published reproductive and mortality data for wild European rabbits in NSW and south-eastern Australia.

Model structure: Monthly timestep simulation. Tracks adult females, adult males, and juvenile cohorts by age. Breeding occurs only during the selected breeding window (default June to November for southern NSW, per NSW DPI: "In the south, breeding usually starts after autumn and finishes in late spring"). The window is adjustable per property; NSW DPI notes that timing varies with rainfall and green feed availability. Annual litters are distributed evenly across the breeding months. Offspring sex ratio assumed 50:50. Juveniles graduate to breeding adults at 4 months of age (NSW DPI: sexual maturity at 3 to 4 months).

Reproductive defaults: 7 litters/year at 7 kittens average (~49 kittens/doe/year). NSW DPI states does are capable of 7 to 8 litters per year with first litters of 4 to 5 kittens increasing to ~8 in subsequent litters, producing 50 to 60 offspring per breeding season in favourable conditions. The defaults sit at the low end of this published range. Sliders allow adjustment up to the maximum.

Net estimate model: Applies kitten mortality and adult annual mortality, converted to monthly rates. The removed founders are treated as wild adults: had they not been removed they would have faced the same natural mortality, so they decay at the adult rate along with their descendants. This keeps the estimate a realistic counterfactual rather than assuming every removed animal survives and breeds for the full projection. Baseline rates:

Kitten mortality: 80%, NSW DPI: "Kitten survival is low with up to 80% dying before they reach 3 months of age."
Adult annual mortality: ~65%, from Moriarty, Saunders & Richardson (2000), central-western NSW: 274 radio-tagged adults, 82% total annual mortality (predation 44% comprising foxes 28%, raptors 10%, cats 6%; RHD 16%; myxomatosis 9%; other 13%). The ~65% default excludes the RHD component, since RHD/RHDV mortality is endemic but highly variable by season and site. The slider adjusts ±5% for local conditions; the full observed rate including RHD was 82%.

Both rates are adjustable by ±5% to account for local conditions. The shaded band on the chart shows the output range across ±5% from the selected rates.

Pasture impact: the rabbits-per-sheep ratio is adjustable (default 10). NSW DPI cites 9 rabbits = 1 dry sheep equivalent as the highest-impact figure; higher-rainfall areas are commonly 12 to 16. Feed (dry matter) and the sheep-equivalent both scale with the ratio: a dry sheep equivalent eats about 1.125 kg/day, so a rabbit eats that divided by the ratio, which is NSW DPI's 125g/day at 9 rabbits per sheep (within their 100 to 150g range). The annual figure is the standing population's yearly rate, not feed eaten over the whole projection.

Sources:

NSW DPI, Rabbits: Species Information: breeding parameters, kitten mortality, feed intake, sheep equivalence.
PestSmart, Economic and environmental impacts of rabbits in Australia: pasture and sheep-equivalent ranges.
Moriarty, Saunders & Richardson (2000): Mortality factors acting on adult rabbits in central-western NSW. Wildlife Research 27, 613 to 619. doi:10.1071/WR99084.