House wrens nest in old woodpecker holes, natural cavities and nestboxes. Although these tiny birds are easy to spot at nestboxes, finding their nests in natural settings can be more of a challenge. About a week ago Leonard and I were near the Ash Creek Lower Campground (Lassen County CA) and noticed house wren activity around a western juniper (Juniperus occidentalis) on the bank of the creek. The wrens were bringing insects back to the juniper and disappearing into an open crevice in the trunk, evidence of a nest and chicks. How exciting to watch those industrious parents.
Four days later Leonard and I returned to the house wren nest. I was expecting to take more photographs – perhaps one of the young house wrens would even pop its head through the crevice. There were no house wrens to be seen. I waited and waited without seeing or hearing one wren. Finally I went and peeked into the crevice which was eye height. Nothing!! In those four days the wren babies fledged. It did not appear that the parents were planning a second brood this season, at least at this site.
Last summer I described house wrens in a post that can be found here, so I will not repeat myself. One other interesting fact I did learn was that temperature is very important to house wren egg survival. Temperatures in the nest of over 106°F for more than about an hour or under 65°F for more than a day will kill the eggs.
I will need to watch that juniper crevice next season to see if the house wrens return.