The Urban Pantheist (urbpan) wrote,
The Urban Pantheist
urbpan

Blue Rabbit Urine

At my work, there is a recurring report from people tracking animals in the snow; a bizarre and lurid claim of blue rabbit urine. After six winters there, I have finally witnessed this first hand. Before seeing the blue stain on the snow myself, I was frankly skeptical, and assumed that people were seeing something else, and mistaking it for blue rabbit urine.

A quick search turns up one article on the phenomenon--posted by an "urban field ecologist," no less--from the previous winter. You can read it here: http://nuthatch.typepad.com/ba/2005/12/blue_smurf_pee_.html Another reference to this, with anecdotal experimental information is here: http://www.ont-woodlot-assoc.org/sw_nonfibre_redskies.html

The gist of it, is this: Our native rabbits (the eastern cottontail) have been browsing on an alien shrub (European buckthorn). The buckthorn contains a chemical that passes out with the urine, which comes out yellowish to brownish, but after exposure to sunlight, turns a lovely blue color. This effect is visible, of course, because the urine in question is suspended in snow. You would think that the cottontails are eating the berries of the buckthorn, because they are purplish, but according to the second reference above, the effect occurs after the rabbits eat other parts of the plant. Buckthorn holds its leaves long after most native deciduous plants, and in winter cottontails subsist largely on bark and twigs. The second reference also emphasizes that buckthorn is not a favored browse plant of North American herbivores, and that they have to be driven to feed on it out of desperation. I'm not sure about that; my workplace has enough Norway maple saplings to sustain a cottontail factory farm.

So, without further ado (okay, one doo) here is some blue rabbit urine:

Tags: blue rabbit urine, buckthorn, eastern cottontail, photos, snow, tracking
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  • Fall walks, part two

    On October 8th, we went to Cutler Park.

  • Identifying animals from plants

    The plant is a black cherry Prunus serotina, a weedy little tree found throughout the New World. The leaf bears the mushroom-like galls of a tiny…

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    These little black aphids are feeding on our nasturtiums. I was aiming to get a good sharp view of them and ended up with something softer and more…