I'm thinking of buying some chemicals for blood trailing this year. They have these lights for trailing deer that are supposed to make the blood more visible but I'm thinking of another option. In the world of crime scenes, there are several reagents for finding blood. Luminol actually makes it glow brightly in the dark. The blood will give off a bright blue glow. Blue Star does the same thing. During the day, protein dye stains like Amido Black and Sudan Black bond with the protein molecules in blood and turn it completely black. I know it would work, I just don't know how feasible it would be. Maybe after you have visibly exhausted the visible trail you could break this out and find those less visible traces. I'll let you know how it works. Hopefully whatever I shoot drops in it's tracks, but you never know.
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The fear of you and the dread of you shall be upon every beast of the earth,upon every fowl of the air, upon all that moveth upon the earth, and upon all the fish; into your hand are they delivered.