Local mystery solved.

This news from our winter pine marten researcher, Katie Moriarty:

Well, my curiosity is more settled and I wanted to share the wealth. I've been seeing what I thought were a lot of kill sites without any sign of struggle or fur... As it turns out, red pee in snowshoe hares (and other lagomorphs) is fairly common. Never had a rabbit as a kid, never knew...

Changes in urine color in hares seems to be linked to ingestion of conifer needles. The citric acid created contains porphyrins, which are some sort of circular carbon chain, and through digestion these combine to form heme (iron compound). Another source stated this is a symptom of excess calcium. It seems that the phenomena of red urine is temporary, lasting only a few days and does not occur uniformly across rabbits with the same diet.

Another website (probably unreliable) stated that blue urine in hares was caused by a diet of Rhamnus cathartica, European or cathartic buckthorn. The urine of domestic buckthorn eaters is initially yellow or brown, but within ten minutes of exposure to sunlight turns bright blue in the snow or on paper.

I never knew that urine naturally changed colors. I also thought it was curious that there could be photosynthetic blue urine (maybe) of all things.

Hope you have an enlightened day...

Peace, katie