fine detailing is very hard to achieve with the HS10 /20 isn't it.
I was very disapointed with many of my initial images. They would seem ok until you cropped them when they became either pixelated or slightly blurred particularly feathers.
There are numerous reasons for this and they can be largely overcome with a little practice.
The first thing to do is to get off Auto
Birds move quickly so you need to make sure that your speed setting is adequate before anything else.
For bird shots I tend to use S mode and set the speed as high as I can, say 200 or 250 if there is sufficient light ,no less than 125 or you'll get blurred shots if there is the slightest movement or twitch.
Then I make sure that the subject is not next to other objects at similar distance or the cameras focusing will be hunting between the objects and not settling on your subject. A typical example would be a bird on a bird feeder. The camera is always going to focus on the larger object and because they are typically round it makes focusing even more difficult.
if there is a golden rule about bird photography it must surely be 'don't take a picture of a bird on a bird feeder'!
Best to set up exactly where you want to picture and entice the birds there with peanut butter and dried mealworms or cake etc . Set up the camera on a tripod and try a few test shots then wait patiently until a bird lands . That way you'll end up with professional looking images.
After much experimenting i have found various settings on the camera which cuts down on the amount of post image processing which the Fuji does which results in loss of fine detail. Essentially the camera's software is trying to compensate for camera shake by blending the edges of the image.
Two things that will reduce this is using a tripod or monopod or even bracing against a door frame or tree etc and the other thing is to not use the maximum telephoto magnification. A cropped image taken at 400mm is likely to be a better image that one taken at 720mm