House Wren-predator drama
- House Wren babies just hatched three days ago in a nest box outside my house. I've been watching the parents running themselves ragged bringing insects and caterpillars, and leaving with fecal sacs. It seems like one or the other parent came with food about once a minute.
About half an hour ago I heard frantic alarm chattering outside. I found the two parents flying to the nest hole, fluttering for a few seconds, and then leaving. Over and over again the parents narrowly avoided colliding with each other. They kept up an intense chatter-buzz the whole time. An Oak Titmouse, a Lesser Goldfinch, and an Ash-throated Flycatcher came and perched close to the nest. The forays went on for quite some time before I saw light bouncing off something just inside the black opening of the nest box. Then it moved. My first thought was that I was seeing a baby bird's head, but then I realized it didn't look quite right. I finally figured out I was seeing a snake's head. I called my neighbor, Gaby, to come watch.
The snake was apparently ready to leave. It stuck its head out a few times, but every time it did so the wrens attacked. I was taking pictures, so I couldn't see well what was happening, but Gaby saw it get hit a few times. At her suggestion I finally turned on the movie feature of my camera and filmed the rest of the drama. The birds kept dive-bombing the snake as it stuck its head out. Finally the snake decided to make its escape. It wound out of the hole, coiling and counter-attacking twice in the process of exiting. It successfully made it down the tree. It was a 24-30" gopher snake.
I thought that was the end of the story, and came into the house. After a while I heard intense titmouse chatter and went back out. Titmice and several other species were mobbing something down the hill. I suspected the gopher snake heading down into the draw was the object of their attention. As I was trying to figure out what was going on I heard peeps from the nest box!
An adult wren approached the opening and veered away, apparently in fear. It had a crane fly in its bill. The other adult came close and swooped to the side. They kept up an approach-and-retreat flutter dance for a few minutes. Finally the one with the crane fly perched on the edge of the opening, leaned forward to deliver the food, and flew away immediately with a fecal sac.
I will never know whether the gopher snake ate any babies or not. It's hard to believe it wouldn't have wanted to eat all of them, however, once it was inside the nest. Did the wrens successfully scare it off? It seems possible.