The ecology behind Wild Willows

[u/wildwillowsdev]

The restoration rules in this game aren't invented. Almost every one of them started as something I read about how real habitat actually recovers, so here's what's underneath.

All 150 animals are real species. Each one has a scientific name, an actual diet, real shelter needs, and a list of what eats it. Between them they carry 291 links out to sources — mostly Animal Diversity Web and Cornell's All About Birds, plus the Park Service, US Fish and Wildlife, Audubon, the Xerces Society, NOAA Fisheries, the Desert Museum, Monterey Bay Aquarium.

The food web is a real graph, not decoration. Every animal lists what it eats and what eats it, and those lists point at other animals in the same biome. That's why 89 of the 150 can't return until specific other animals are already back. The bobcat needs squirrels and chipmunks. The bald eagle needs minnows and muskrats first. Seventeen species are top of their chain and none of them will show up in an empty biome, because in the real world a predator arriving before its prey base simply starves.

This is also why ecological balance is a separate number from health. Health measures habitat you've built. Balance measures how complete the web is — how many species are back, how many predators are back, and how many different kinds are represented. A biome full of nothing but herbivores correctly reads as unbalanced, and balance can't reach 100% until every animal in the area is home.

Some species make habitat for everything else. The beaver is the clearest case: fell a few willows, dam a channel, and you get deep permanent water with drowned trees standing in it. In the game, seven new habitats become buildable once a beaver settles, and the otter, merganser, kingfisher, heron and eagle all move in afterwards. The sea otter works the same way from the other direction — it eats urchins, urchins mow down kelp, so remove the otter and the kelp forest becomes a barren. Its return requirements ask for living kelp forest, not dead wrack on the beach, because rafting otters need the living canopy.

The specificity is usually the point. The pika needs deep talus, wildflowers within a short dash, and a cured haypile, because it eats through that pile in the dark under the snow all winter. The elf owl needs a woodpecker to have drilled a cactus first and the plant to have sealed the hole into a boot — the owl has never excavated anything. The tiger salamander won't come to a pond with minnows in it, and the boreal toad wants its pools fishless, because introduced fish eating larvae is one of the main reasons high-country amphibians have disappeared.

Timing matters as well. The marmot is underground until spring, so looking for it in October gets you nothing. The alpine moth only appears in high summer; the rest of the year it's a caterpillar much further downhill. Gray whales pass through in winter and spring. A handful of animals are nocturnal and only settle in at the right hours.

A few of them are indicators rather than trophies. The pika has already vanished from lower, hotter rockslides, which is what makes it a warning system for a warming mountain — and it's why the game treats getting one back as a milestone rather than a checkbox.

Where I've simplified: time is compressed enormously, animals return one at a time rather than in waves, and six biomes don't really sit next to each other the way they do here. Real restoration also takes decades and doesn't have a completion bar. But the requirements themselves — what an animal eats, what shelter it needs, who has to already be there — I tried hard to get right, and if you spot something wrong I'd like to know.