Hooded Merg Crowns..

Take critter clay and build a pointed wedge on top of the skull. This will allow the crown to be taxied correctly. When done correctly, they are awesome! Here are a couple I did ages ago...https://www.mstaxidermist.com/_DuckHoodies.jpg

 

First get the quills very well cleaned. I take a fresh scalpel blade and gently separate the membrane between the rows of quills and degrease very well. You can use joeys suggestion or apoxy sculpt type stuff to creat a crown on the head before turning the skin back out. I use air to groom . Another trick is to take a probe and work the quills from inside the skin. Check your references as the hood opens up very full, not flat sided at all.
Jim

 

As the others have said plus taxi the skin forward and use air to get it to stand up. I inject caulk through the eye hole to the top area of the head to hold the skin. Cleaning the skin underneath the crest to allow the quills freedom to move is key.

 

Like said above: thorough cleaning to get the quills freed up so the caulk can capture the ends and they are taxi-able. The skin has to fit loose on the skull, if it is tight, the quill bases will be smashed against the skin and lay flat. Same thing happens if there is much tissue left around the quill butts, it will dry/shrink and do the same.

I would use an artificial head. Mergansers have about the smallest bill base of all ducks, so reattachment is a breeze. Doing so will allow you wheel the entire head and get that crest to do what you want.

Its then a preening show, a couple times a day until the caulk sets.