I have to agree with many of the posts provided, but there is a little insight here too so the questions will be answered.
Hanging ducks until there intestines fall out is an age old trick before freezers and meat lockers.
Now aging ducks in the fridge(warmer temps) or in the garage (Cooler temps) is a way to achieve the best table fare.
Here is the reasoning. Any living animal that dies naturally or by hunting will go into rigor, This is when the muscles tighten and the animal appears stiff. By aging the animal the natural enzim's in the muscles will break down and make the muscles relax(24-48 hrs)
after harvest, the longer you age your quarry the better the table fare.
I gut my birds in the field if practal, or at the house immediately following a hunt. To age them we gut them and put them in a paper sack on there backs in the fridge for 3-5 days. They always turn out delicious & tender!
I have a dedicated beer fridge and game fridge for birds and beer!
Click, Bang, Splash, Repeat. Happy Happy.