Hi. Do you have raccoon's in your area?

i do, but it isn't anything this large and racoons would not have access to this feeder. It is logical to me that it would have to fly to be able to reach this particular feeder (of course, I could be wrong). I wish I had one of those cameras that would take pics of what it is.

Flying squirrels will eat suet and they are nocturnal. They are smaller than regular squirrels and polite eaters so they don't usually make a mess. Do you have trees close enough that they could glide to your feeder?

Here's a YouTube video of one.

https://www.youtube.com/watch?v=h7uWFlcHVJY

How interesting .................... I don't know if I have flying squirrels or not, but this could very well be the culprit as "it" did not eat all the suet in one night, and there was no mess..................did not try to pull the plastic container out of the holder. I do have a tree very near the feeder. Thank you for this information.