Also real feathers can be done pretty sturdily depending how you do them. For tail or anything where the feathers are going to be big and protrude from the costume, I'd definitely stick with fabric or leather or whatever - but I did a few iterations of feather bracers for an old character, and the method could be used for other garments too. The bracers are still kicking around after several events of being beaten on and then being donated to NPC camp, and the feathers are still attached and intact. Basically this is for anything where having the feathers flush to the garment is desired.
I recommend using strung rooster coque as it's cheap and the feathers are very bendy, so they don't break like stiff feathers do. Strung coque is better than loose because it's already on a string or ribbon, making it easier to work with. (You don't want to place feathers individually. It's an absolute pain.) I got black dyed rooster coque (great for corvids; birds of prey would be better with natural) by the yard on cord/thick string years ago. Can't find it exactly the same now, but I just received an order from moonlightfeather.com of strung feathers and they're really, really nicely strung on sewn ribbon which will be even easier to work with.
Lay your outermost string of feathers out on the fabric. Glue it on with hot glue at the lower part of the feathers but above the ribbon. Use a thin layer on the fabric, don't go too thick, then press the feathers on. (I'm sure there is better glue for this purpose but hot glue works). After the glue has dried, take a stripe of plain half or quarter inch ribbon just above the feather ribbon and sew it over the feathers and ribbon. There should be a zig-zag stitch on your sewing machine - sew it one way then sew back across so that the zigzag intersects. You want a nice wide reinforcement. I used contrasting thread because I was making these as decorative, but the same color thread would probably be better for something intended to be bird parts.
Then add the next layer of feathers overtop and below the first layer, so that the first layer sticks out from under the second layer but the second layer overlaps the ribbon. Repeat the hot glue/ribbon/sewing step. Keep adding layers until your base material is covered with feathers. Then either leave the last layer of ribbon exposed, add decorative ribbon, add felt/leather/cloth feathers, or whatever you want to do to disguise that last layer.
I someday want to do a cloak or cape like this but it will be soooo expensive. Someday. The original bracer attempt only had the feathers glued on, and they came off so easily. I also tried hand sewing and it was awful, didn't look good, and took forever. Sewing them on with a machine and adding ribbon overtop after also gluing them on was much more stable and secure.