I put up a new hummingbird feeder a couple of weeks ago, filled it, and it was empty by the end of the day. Since there are more hummingbirds in the garden this year than ever before, exponentially so, I figured that they were thirsty and liked the new feeder better than the others.

Then it occurred to me that the feeder might be leaking. That would explain why the feeder is empty at the end of every day. I checked the feeder when I filled it this morning, and saw no evidence of leakage.

But just now, I noticed this. If the feeder isn’t leaking, what’s the explanation for this behavior?