I and some friends, we have a Minecraft SMP Server. We use the latest recommended Version of the Bukkit Server.

We dug a 40x40, 3 tiles high cave and placed grass at the bottom. Than we dug water canals and made a lava trap. The problem is that no mobs spawn there. Above the cave there is sand, but I think that doesn't really matter. The fact is that in other places on our server, mobs spawn. Does anyone know why they don't spawn in the cave?

  • Mob spawning logic has changed recently (1.8 AFAIK), finding a solution to this may require looking at the code.
    – fredley
    Oct 10, 2011 at 11:57
  • 4
    The chances are so low, passive mobs may as well not respawn at all in 1.8. I'm afraid you'll just have to tough it out until 1.9 brings Animal Breeding. Oct 10, 2011 at 12:29
  • I think the main problem is that at night animals will spawn in the dark, whereas before they would cluster around lit grass, making it easy to create 'farms'.
    – fredley
    Oct 10, 2011 at 12:43

2 Answers 2


Actually, the problem is that the cave has a "ceiling".

[Animals] will always spawn on the highest available block in a column i.e. the one that can see the sky.
Animal Spawning at Minecraft Wiki

  • Does this count for all block types?
    – theorise
    Oct 10, 2011 at 14:02
  • @theorise: I see no information about that. Non-opaque blocks may be allowed, but it's unlikely.
    – BlaXpirit
    Oct 10, 2011 at 14:08
  • 1
    Animals only spawn on opaque blocks, so if you make sure that the block (grass) is lit up by sunlight (make a huge hole) and then place glass for a roof, the animals will still spawn on the grass.
    – Mr Smooth
    Oct 10, 2011 at 21:26
  • Wasnt this only supposed to be in 1.9?.
    – Domocus
    Oct 13, 2011 at 15:12


Yesterday I found a great soultion for my problem: The Mobiile Plugin for Bukkit. It has many options to set your own spawn rules, so that animals can also spawn in the animal farm.

Also it's great for creating a mob filled survival map on the server, just set all mobs to AGGRESIVE and set their spawn rate to 10 percent. =D

I just posted that, because eventually someone could need this informations too.


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