Personally, I got this long after finding 250 animal tracks. I am positive that I tracked down more game using blood trails than animal tracks. Some people have said this is glitched, maybe it is. If it is glitched then you may have to delete your save file from the hard drive and start over.
I honestly think that the collection tracker is just misinformed. Maybe as long as the indicator card is up, any blood found is just tacked on to the one you already found. I am not sure, just guessing really.
I will trying playing around with it on another profile and update this later.