[Arrei]

Default Spigot spawning uses an algorithm that takes the spawn cap setting along with the amount of loaded chunks to generate a mob cap on that type. I can't look up the formula at work, but suffice it to say these numbers you have here are only a baseline starting point. For hostiles, animals, and water mobs, our setting is unchanged, but our lower view distance to deal with lag compared to the vanilla SSP distance means SMP has quite a lower mob cap. Ambient mobs, however, are set to 0 so that bats never spawn, as they serve no gameplay purpose and no one even notices they're gone.