I recently got a Cuckoo Maran rooster, he's about a year old. The lady I got him from said that she occasionally needed to clean around his vent because his poops were very runny and it would sometimes get caught in his feathers. The other night I noticed him standing funny so I checked his vent and sure enough, it was all plugged up. As far as I can tell he's pretty healthy besides that, so I'm not sure what might be causing it. All my other birds live on the same feed in the same coop and none have runny poops like he does, or ever got clogged up. And I don't even know if its the feed because I use a different feed then his previous owner and it obviously hasn't made a difference.