Quokka Population Dynamics (2D)

Habitat

Vegetation growth 1.00×

Drought severity 0.60×

Tourism

Tourist disturbance 1.00×

Days per second 8

Live Stats — Day 0

Population

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Carrying cap. K

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Growth rate

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Stress index

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Vegetation

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Water stock

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Births (7d)

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Deaths (7d)

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Quokkas on Rottnest Island have no natural land predators, so their numbers track food, water and human disturbance directly. Push tourist disturbance past 1.0× to see habitat trampling and heat-stress mortality bite into the population.

How it works

The colony follows logistic growth against a carrying capacity that itself depends on habitat condition:

dP/dt = r·P·(1 − P/K) − dExtra
K = Kbase·(V/100)·(W/100)·(1 − 0.3·max(0, dist−1))
r = rBase·(1 − stress)
stress = 0.5·(dist/2.5) + 0.3·(1−V/100) + 0.2·(1−W/100)

Vegetation V regrows logistically each day and is grazed down by the population; water W is replenished by rainfall that shrinks as drought severity rises, and is drawn down by the colony's daily needs. Tourist disturbance beyond 1.0× (its "normal" baseline) trims the effective carrying capacity — trampled scrub, disturbed daytime shelters — and adds a small extra daily mortality term dExtra for heat stress and vehicle strikes near visitor areas, mirroring the documented cost of over-feeding and crowding at real quokka-selfie hotspots. All four state variables (P, V, W and the running stress index) are integrated with a simple daily Euler step; the sliders let you push the habitat past its rainfall/food/disturbance limits and watch the colony's growth curve bend, flatten or fall.