About a year ago when I was out in the backyard filling up my bird feeders I noticed a patch of blue snow. And then another. And another. And yet another. In fact there was blue snow patches all over the yard. Then I noticed beside some of the blue patches were patches of rabbit scat- an Eastern Cottontail (Sylvilagus floridanus) to be precise. Hmmm.
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| Blue Eastern Cottontail Pee |
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| Blue Eastern Cottontail Pee |
Since I assumed that Eastern Cottontail pee is not
always blue I did some research. The reason for the blue pee is not a
shocking one. The blue urine was the result of diet of European Buckthorn (Rhamnus cathartica). While this may not be surprising to those familiar with the plant (European Buckthorn has dark purple berries), what is strange is that this colour seems to be the result of eating the twigs and bark and not the berries. Even more bizarre, 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. Eastern Cottontails do not regularly eat European Buckthorn, so these
blue spots in the snow can indicate that the rabbits are stressed for
food.
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| Common (European) Buckthorn (Rhamnus cathartica) |
Mystery of the blue pee- solved! You never know what you will find in nature but there are always interesting surprises.
~Kristen Martyn
Posts
I just landed here on this page from googling what are the blue spots near backyard wildlife- rabbits and squirrels are. This makes sense!
ReplyDeleteSo glad you found this useful! I wrote the post back in 2015, but am seeing lots of blue pee this year too! :) ~Kristen
DeleteJust discovered this in 2019...I figured it was something like this. Thanks!
ReplyDeleteIndeed! I've been finding it a lot this winter in my yard as well. :)
DeleteA friend of mine, who is a naturalist, shared this the other day. Today, mt boys found blue snow while we were out on a nature walk. There was plenty of buckthorn around. They were so amazed by this! Thanking for sharing this information. It was fun both to find the blue snow and to be able to answer their questions about it.
ReplyDeleteHi Jessica! Glad we could help solve a mystery ;) Kristen
DeleteMystery solved, thanks.
ReplyDeleteYay! :) Glad the article helped.
DeleteHaven't had rabbits in many years due to large owl population and this year's 2020 owls are down with the rabbits all over the place. While picking up after dogs in back woods blue spots threw me. Lots of snow and buckthorn back there. Thanks!
ReplyDeleteHow lucky you are to have so many owls! Glad you liked the article :) Kristen
DeleteBlue snow in the back yard. At first i thought my dog puked after eating something he shoudn't have. Then i saw the pile of little caesars sausage and googled "do rabbits pee blue"
ReplyDeleteAnd indeed they do pee blue! :) Kristen
DeleteHi Kristen,
ReplyDeleteAre there any papers citing this or more resources looking into the chemistry or biology? I have read a lot of anecdotal accounts of the Buckthorn bark, but nothing more rigorous and would love to learn a little deeper.
Do you know any such resources?
Hi There,
DeleteTo be honest I haven't dug into any scientific research. Most of the other information out there are anecdotal observations. But if you find anything I'd be very interested to learn about it. :)
Kristen
Blueberry Snow anyone? LOL
ReplyDeleteLOL
Delete