Bird placement rules: biome weights from the world's biome mix (pass world.options.biomes ids), and an air band between the species' altitudes above the ground (or water, if it flies over water).
world.options.biomes
Bird placement rules: biome weights from the world's biome mix (pass
world.options.biomesids), and an air band between the species' altitudes above the ground (or water, if it flies over water).