(Posted by Carol Cummins <carolcummin...@gmail.com> via moumn.org) While tending bluebird houses this year, I came across some unusual behavior. A Chickadee nested and laid 4 eggs in one of the boxes. The following week, a Tree Swallow flew out of the same house. There were now 7 eggs in the nest including 3 swallow eggs. The swallow had also added the usual feathers typical of their nests. For the next few weeks the Tree Swallow was incubating the eggs, but would not leave the box during my visits. I have no idea if the swallow incubated all 7 and whether they all fledged. I have tended a group of 16 bluebird house for about 5 years and have never observed this behavior. How common is this? When two birds simultaneously use a nest, does one species prevail? Or are eggs and/or fledglings rejected? Any other insights?
Thanks. Carol Cummins, volunteer Minnesota Bluebird Recovery Program ---- General information and guidelines for posting: https://moumn.org/listservice.html Archives: http://lists.umn.edu/archives/mou-net.html During the pandemic, the MOU encourages you to stay safe, practice social distancing, and continue to bird responsibly.
