One of Nature's Mysteries Solved

Earlier this winter, I wrote a post in my other blog: Snapshot of 21st Century Nature Study. It is a blog I use while I teach a college class on nature study.  Here was the post. Read on for how this mystery was solved:

Mysterious Pellets

Lots of things in nature are mysteries waiting to be solved.  And each time I encounter something mysterious, it leaves me in awe of nature and aware of how much I do not yet know.

So this winter, for the first time, I saw something mysterious underneath my birdfeeders..a mystery that I hope the readers of this blog will help me to solve.

Under the feeders are small, about one inch long, pellets composed almost entirely of the hulls of sunflower seeds (the food in the feeders).

It seems likely that something that visits the feeder left these behind. But what?  We have lots of visitors, but I thought only raptors made pellets.  Could other birds?  Could mammals?

I had read that crows, blackbirds and pigeons could also produce pellets.  We do have flocks of blackbirds, but they do not come every day.  These pellets are deposited with great regularity.  At first I thought it might be the mourning doves that we see, but they are usually not under this feeder--the closest one to the house.

So I googled "regurgitated sunflower seed pellets" to see if I could find the answer there.  There were a couple of blogs that mentioned strange pellets.

One blogger ended up trapping a chipmunk and saw the pellets in the cage with the chipmunk. But we don't have any chipmunks in our woods.  At least that solves the mystery of "could mammals produce pellets of regurgitated food".

Another blog called the pellets "possum pellets" and has observed young possums at the feeders.  I certainly have plenty of possum in my woods, and they are great scavengers.  So this may be the "culprit".

The gaiagarden.blogspot.com post had a better picture that looks identical to the situation at my feeder:

So, while possums are a good bet in my situation, I was still not totally convinced. After consulting my mammal books (Wild Mammals of Missouri  by Schwartz and Schwartz and Mammals of Illinois by Hoffmeister), I found neither mentioned sunflower seeds in the diet of opossum or this ability to form pellets.  Perhaps it is a big omission.  It is noted that possums are scavengers and eat corn, a less preferred food, in winter when other foods are not available.  It would seem to me that sunflower seeds would also fall into this category. 

What do you think?  Is it an opossum leaving the pellets...or something else??

Mystery Solved:

A week or so ago, my husband and I saw an opossum under our feeder. It was clearly chewing sunflower seeds.  It would take a mouthful and chew and chew, then open its mouth and spit.  This action reminded me of baseball players that chew sunflower seeds, move them around in the mouth to get the meat out, and spit out the hulls.


We watched as the possum slowly moved on...looking for food elsewhere I imagine, after a hard winter.

So the pellets we saw were not regurgitated because they never left the mouth to enter the digestive system.  And they are held together by the saliva of the animal. 

I am still amazed that this behavior is not documented in any reference book.  It just shows that we don't know everything about even the commonest animals.

I was glad that, through continued observation, we could solve this mystery.