RE: Shot a BIG ONE!! but havent recovered it.
Neck hits [:'(].
You hit the jugular and you recover them fast. You miss it.....i have never heard of one being recovered from a neck hit in a timely manner after traveling near that far (1000+ yards). He will probably die eventually too if you made a solid hit in the neck region(based on what i have seen and found laying in the woods). Check the thick stuff, particularly near water, as mentioned.
I have been in on several intentional and unintentional neck nit trailing jobs (not mine). They bleed like crazy and just keep going if you miss those big arteries and veins right under the vertibra. They get found a week or two later.
I am sorry that that happened to you, hope you revise whatever you find you did wrong.