Don’t eat the blue snow either
Infrequent birding increases my stress level. This winter has been quite the test because we have had temperatures as low as -27 degrees Fahrenheit followed by snow-melting days followed by another deep freeze that has created icy conditions…that even the best footwear barely can handle! But I’m desperate and need to be outdoors. Though birding opportunities are slim, there are many things to research in nature if you search.
One of the more curious things I’ve found in my neck of the woods is blue-colored urine patches in the snow. I can tell by the surrounding tracks that a cottontail has been in this post, and it looks like their urination pattern. I know from personal experience that some medications can cause your urine to turn blue, but who on earth would prescribe bladder infection medicine to a wild rabbit?
Something else is going on here! It’s a surprisingly unstudied effect of European buckthorn. In winter, rabbits will browse on all sorts of branches and bark to survive. When they go for the ubiquitous buckthorn it affects their urine. It exits the lagomorph the usual brownish yellow, but it when exposed to light, the urine turns blue.
Most of the information about this phenomena comes from two blog posts on the Internet. The only real “study” on this was by a man in Canada who had noticed the blue spots in his yard and fed buckthorn to his domestic goats and rabbits and got them to produce the blue urine.
Not everyone with buckthorn finds blue rabbit urine. Could this be that rabbits would rather browse any other tree and only eat buckthorn out of desperation? I haven’t noticed the blue urine in my neighborhood until the recent subzero snow and ice. Nature always has more to teach us, especially as we navigate invasive plants taking over a landscape.