Minecraft – Too many ender dragons

The issue I see is (especially on SMP) Mobs are loaded before blocks (last experienced this on 1.2.4) so they move before the walls/blocks load. I have lost many a chicken this way.

also this is made worse on SMP as the chunks are loaded/unloaded much more often.

Edit: should have mentioned, there is a fix for this in the next release, but until then, the only way is to stay with your birds at all times.

Edit 2: the only fix I can recommend is to replace all the wood with glass and hope for the best, as you are on SMP I would also hide this whole thing in case it is a chicken hunter, not a bug killing them.

I was able to talk about my problem to the Creator of the linked Video above myself via Teamspeak.

Here are some things to keep in mind when building a huge farm like that:

• You absolutely need to clear out a HUGE perimeter around the farm to make sure mobs can only spawn in the area you want them to spawn.
• The perimeter around the farm needs to be 128x128. In my case i only cleared out like 50x50 which is by far not enough and the main reason i got extremly low spawn rates compared to JL's video.
• In MC 1.7 and before it is extremly important to notice that the LC Value (as seen in the debug screen) has a huge impact on the farm and spawning behaviour. The LC Value saves for the given chunk how huge the player has builded in this chunk ever since creation of the chunk. For example you go in newly generated terrain at Y = 50 the LC Value will be 50. If you build a 10 high tower on that place the LC will go up to 60. Note that to have good spawning behaviour your LC value needs to be as low as possible.
• Explanation why the LC Value needs to be as low as possible: When MC trys to spawn a Mob in a given chunk, it only will try to spawn it in the area of the chunk under the LC Value. So, if there are several chunks around your farm with a high LC Value, the higher the chance is, that mobs outside of your farm will spawn, because the given chunk actually has more blocks to spawn mobs upon.
• There also is a mobcap on each MC server. So, if you are alone on the server the complete Mobcap will only be taken by you. If there are more players on the server and they even are in different regions, than statistically each player would get halve of the mobcap which means getting halve of the mobspawns.
• There also is a possibility that mobs will be spawned at the edge of the 128x128 perimeter and not despawn instantly due to a bug / feature. JL told me that when a mob is spawned directly at the edge of the 128x128 perimeter and it touches the end of the render distance the game will put this mob into a "sleep" mode thus stopping rendering it. This however causes the mob to still count to the server mobcap while not despawning. Which means it lowers your spawn rate.

This are the reasons i remember, actually JL has told me far more. I convinced him to post a video on that topic on youtube and explane the topic far more in details. The video will come soon from him.

Hope this helps somebody.