Wither Skeletons in the Nether

A question: does Skeleton spawners in the nether spawn withers?(They do, I know)
If yes, So why doesn't it spawn for me?
It only spawns normal Skeleton archers.

 

I think it has to be in a certain radius of a nether fortress.

 

Proven Wrong. I've done this outside of fortresses and on top of the nether in other servers. On SMC, I've placed the spawner inside the nether fortress.

 

Yeah then I don't think it is on our servers and was probably a plugin on the other ones.

 

It doesn't really need a plugin. As long as there's a skeleton spawning in a nether fortress, there's a percentage of it spawning as a Wither Skeleton.
I think it's caused by SMC's spawner plugin that disables it to spawn any other mobs other than that of the spawner itself.

 

it doesn't and shouldn't spawn wither skeletons. we don't need people farming infinite wither skulls to make withers that easily. just wander a fortress long enough and you'll get plenty to kill, just like the rest of us.

 

The answer i'm looking for. Thank you.