fuck, this was supposed to be a quick drawing and now I spent half of my day on ittt
oh well maybe the next one will be faster (no it won't, but there is hoping)

...
oh right, as for the tail! I noticed that Centalmons/Centarumons tail has a similar property as birdramons body, you just need to look at the official art.
Like... sometimes Birdramon is "made" of fire and sometimes, when a different art style is used, it's just orange feathers.