Island Tameness: Naive vs Wary Prey Simulator

Introduced Predator

Simulation speed 1.0×

Populations

🏝️ Island (naive)

–

awaiting predator

🌍 Mainland (wary)

–

awaiting predator

Island kills

Mainland kills

Why the same predator, two outcomes?

Species that evolve for many generations without predators — on an isolated island — lose the flight response, camouflage and rapid reproduction that cost energy to maintain but serve no purpose when nothing is hunting them. This is called island tameness.

Island (naive) prey do not recognize the newcomer as a threat and keep wandering; the predator walks straight up to them.
Mainland (wary) prey evolved alongside a full predator community — they detect the intruder at range and actively flee, and their species breeds faster to offset losses.
The predator itself is identical in both scenes — same speed, same strike range. The divergence in outcome comes entirely from the prey's evolved (or lost) behavior.

Watch the chart below: the island line typically nosedives toward zero, while the mainland line dips and re-stabilizes — the real-world pattern behind flightless-bird and ground-nesting-seabird collapses after rats or cats reach a predator-naive island.

🏝️ Island — no evolved defensespredator-free evolutionary history

naive prey –

🌍 Mainland — coexisted with predatorsconstant predation pressure

wary prey –

Population over time Island (naive) Mainland (wary)

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