Mystery Solved... Maybe?

Two years ago we decided to install a fountain in the back yard, partly for our enjoyment and partly to provide a reliable water source for the birds that visit our shrubbery and bird feeders.  We had had a birdbath in the garden for some years, but we called it our "bird repelling fountain" because birds seemed reluctant to have anything to do with it.

We finally realized that the basin was too deep to interest the birds, even if we put rocks in the bottom of the basin, although in this picture clearly somebody, probably a largish canine somebody of the coyote variety, was interested in the water and knocked it over.  Since there was no pump, the water in it did not move and we had no desire to breed mosquitoes.

Old Birdbath--Somebody Wanted the Water

So we decided to put in a tower fountain with a pump so the water would circulate through it.  We found one we liked that had several levels so that the water bubbles up through the levels to the top level and then trickles down the sides to the basin at the base of the tower.  The guys who installed it had told us we could add some rocks to control the amount of bubbling from the top.

Tower Fountain, Complete With Birds

Things work reasonable well most of the time and the birds seem to love it, but last summer and again this year for the last couple of weeks, large quantities of water have vanished from the fountain overnight, almost every night.  We were baffled as to why so much water was disappearing.  Evaporation?  A pack of thirsty coyotes?  Raccoon bacchanalia?   Communal crow bathing?   Possibly a two-legged critter coming up through the canyon in search of water?  That last thought was a little unsettling.

Evaporation seemed unlikely since the water levels didn't change much during the hottest part of the summer days.  The water level would go down a little during the heat of hot summer days, but most of it seemed to go at night.  We knew that coyotes visit the garden from time to time--we've found piles of poop and other evidence of their presence, but it seemed unlikely that they would be here every night.

We were so curious that Cindy gave me a trail camera for Christmas.  The camera has a motion sensor and infrared capability, so I set it up in hopes of finding the solution to the mystery, but.... nada, nothing, no varmints.  A few curious birds seemed interested in the new shiny thing, and a few California Ground Squirrels visited the fountain for water, but nothing else.  We knew that the infrared feature worked, because we used the camera to film a curious neighbor cat who was coming to the door to taunt our cats, but the camera picked up nothing in the back yard at night.

We had noticed that there were often large splashes of water outside the bottom basin that didn't seem to be accounted for by bird activity, so Cindy decided to unplug the fountain, let the water settle down and then plug it back in the other morning.  The result was a geyser that shot up into the air, splashing large quantities of water out over the side.

So now it looks like either there is something about the fountain as it is presently configured that makes the water shoot up like that.  We'll just have to figure out whether it's calcium deposits that have built up, or the way the rocks are arranged, or what it is that's causing this.

My favorite theory was the Raccoon bacchanalia, but that's not what the evidence showed.  It's something of a letdown--maybe, as Pogo says, "we have met the enemy and it is us."