Trophic Cascade: Landscape of Fear

Apex Predator

Simulation speed 1.0×

Ecosystem readouts

Predator

Absent

Herbivore pop.

–

Direct kills

Riverbank grazing

–

Riverbank vegetation health

–

🦫 Beavers

🐦 Songbirds

How it works

When the wolves are removed, the elk herd grows toward carrying capacity and — critically — grazes everywhere it likes, including the open, exposed riverbank, because nothing there threatens it. Sustained browsing keeps young willow and cottonwood shoots cropped to the ground, so the riverbank stays bare and erodes.

Reintroducing the predator does two separate things at once: it thins the herd through direct kills, and it creates a "landscape of fear" — elk that stray into the open riverbank are easier to catch, so the herd learns to avoid that zone even though most animals are never actually caught. That behavioral shift, more than the population drop alone, is what lets riverbank vegetation recover — which is why beavers and songbirds only return once the bank is healthy again.

Predator toggle — remove or reintroduce the wolves and watch both effects (population + behavior) play out over simulated seasons.
Direct kills — the population component: wolves occasionally take an elk when predators are present.
Riverbank grazing — how much active browsing pressure the marked riverbank zone (blue) is under right now.
Vegetation health — recovers slowly when ungrazed, degrades under sustained browsing; crossing thresholds brings beavers and birds back.

Elk (herbivore) Wolf (apex predator) River / riverbank zone Beaver Songbird

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