At the parking lot, a scolding House Wren voice caught my attention. Following the sound, I spotted the wren about 30 feet up in a cottonwood snag. The wren was moving from branch to branch in an agitated manner close to a cavity in the cottonwood. I figured the bird was near its nest cavity and perhaps gathering insects to feed young. I kept waiting for the bird to go to the cavity, but instead it seemed to circle the area of the cavity, moving about with great agitation.
When the bird moved higher in the snag, I suddenly saw the source of the agitation. Hanging from a fork in the snag was about a one-foot length of a good size gopher snake, The head and front of the gopher snake were hidden within a second cavity about 6-8 inches above the first cavity. About that time, I noticed a second agitated House Wren also scolding and dancing around the snag in agitation. As I watched, the wrens repeated struck the snake on its body where it disappeared into the nest. Realizing the gigantic mistake of not at least putting the camera in the truck, I decided to at least capture an audio recording. The situation was not favorable for audio, with Left Hand Creek roaring in the background and picnickers reveling. Nevertheless, I got a recording and fortuitously, two Lesser Goldfinches showed up to join briefly in the mobbing.
I then made a futile effort to get a smartphone photo of the events. At some point between recording and photographing, I looked up with binoculars to see a wren tail on top of the snake disappear into the cavity. From that point on, there was only one scolding wren, and I concluded that one of the distressed parents had attempted to attack the snake in the cavity.
I noticed at a few points that the snake's body bulged in the area just outside the nest cavity. When the snake finally emerged from the cavity, there was a prominent bulge behind the head. I was familiar with this phenomenon from an experience many years ago in New Mexico when i was wading in a wetland checking waterfowl nests. I found a coot nest with eggs and resting on the nest was a gopher snake. While I watched, the snake slowly open its mouth wide and engulf an egg. As the snake swallowed the egg, a bulge moved along its body. at some point there was a contraction of the body, and the bulge elongated. The snake repeated the process many times as it dined on the eggs.
When the snake at the wren nest pulled out of the nest, it hung for a few minutes while the remaining adult wren continued to scold and attack. At one point, the snake lunged with mouth open at the wren. The wren escaped.
Just as I thought the drama was over, the snake reentered the nest and remained for several minutes before making a finally withdrawal. It then rested in the fork of the snag.
My feeble efforts to capture this drama in photos and recording are included in this eBird list. https://ebird.org/checklist/S70811931
Gopher snakes appear to be efficient predators on bird nests. On another occasion during the second Colorado Breeding Bird Atlas field season, I was working the Fort Morgan block. At Riverside Park, I heard a great commotion of scolding Red-winged Blackbirds. When I walked to the edge of the dense cattails, I found one male
red-wing socking a gopher snake that was partly in a nest in the cattails. For several minutes, I followed along the shore as the scolding moved through the cattails. From time to time, I could glimpse the snake glide up into a nest, then on to the next.
From time to time when we bird, we see the face of the struggle for survival.
Chuck Hundertmark
Lafayette, CO
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