Hi Kevin,
Just a thought from outside the box.
For such a delicate looking item, I'd look at fine down from cushions.
A few of these should splay out quite nicely in a group.

Cheers,
Andrew

I would use some bristles from a microfibre brush of the appropriate colour. I think it's virtually impossible to sculpt it realistically.

Bill

Bristles/horsehair/fibres of some form. Marcus used bristles for the plume of his Tesserarius in the Camulodunum vignette and it looks very realistic:
https://www.planetfigure.com/threads/the-battle-of-camulodunum-1-16-diorama.298791/page-10

It depends on the scale/size, too. I've sculpted a similar plume for 54mm figures. I used a piece of fine wire as an armature, then made a flattened oval out of Aves A&B. I used a Nr. 11 X-Acto blade to texture it. That worked well enough in that size.

Prost!
Brad

As Ray Lamb 50 years ago, using a nylon rope untwined, brushed and a knot at one end with a firelighter, then cuted at desired size en form with little scissors
He made with that fantastic horse tail and mane


Nap ! You are the one who asked ?

But if it's for a bust, I would suggest thin optic fiber then a LED and a button battery ... No friend .. joking

Try using a cheap synthetic paintbrush - the bristles are already white and you can splay the ends by immersing in hot water and stippling on a flat surface......

go in a fish shop and buy the feathers of the right color

A fly from a fishing shop as suggested, may do the trick..

No real feathers allowed......Looks too hokey......Imagination rules.....

Trouchcatchers in the UK are fly fishing specialists or ebay