Monday, March 19, 2012

Bluebirds, Mice and Wood Ducks

Male Bluebird waits for his nest box to be cleaned

Around the Nature Preserve the Bluebirds have been singing and even checking out some of their nest boxes. I just finished cleaning out around 100 boxes –and, apparently, not a moment too soon. While I worked, a Bluebird pair was on the other side of the field monitoring my progress and eagerly waiting for me to finish and leave, so they could resume their house shopping.  I’m always hopeful that we’ll have many pairs of Bluebirds taking advantage of the boxes, but it’s never the case. At best only 3 or 4 pairs will ultimately take up residence.  Part of the reason for the low number is the changing landscape at the Preserve. As the trees in our reforestation fields mature, the habitat in these former agricultural fields becomes less viable for Bluebirds and Tree Swallows. As the young trees grow, the habitat becomes more suited to the needs of House Wren and even to Chickadees and Titmice.
The early bird gets the best house (male and female Bluebirds)

The Bluebird male will enter a prospective nest box home, and if it seems to pass muster with him, he will perch on top of it and try to coax his mate over with a song. The female then comes to inspect the inside of the box. If she shares the male’s opinion, and finds it suitable, she may begin collecting material and start constructing the nest. She will do this on her own and with no help from the male.

Fear not! This mouse will not be evicted

While I was cleaning out the boxes, I came upon many mouse nests. Several of them were still active and so I had to leave them in place. There’s nothing quite like opening a box and having a worried mouse family staring me in the face. I felt the need to assure them that I wasn’t there to foreclose! The materials used to create the mouse nests varied greatly. Some were white and soft as silk –made up of finely cut milkweed parachutes.
Tree Swallow nest lavishly decorated with turkey feathers
Milkweed silk used for a mouse nest
It’s fascinating to find several nests in one box. It’s a little like excavating an ancient city with distinct layers –one on top of the other –each representing a successive era of habitation. Of course with the nest box, all of the different strata were laid down in a single year. One box had a bed of moss on the lowest level –brought in by a chickadee as the original occupant. On top of that was a Tree Swallows distinctive design: a grassy cup nest decorated with various bird feathers. On top of that was a haphazard assemblage of twigs –the work of a male House Wren. This wren nest is what is known as a “dummy nest” –never used, but one of several created by an individual male. At least a dozen small white Cocoons from moths are attached to the twigs in the wren nest. The very top and most recent layer was the nest of a White-footed Mouse.
Male Wood Duck checking the trees for suitable nest holes
Also cavity nesting ducks - the Hooded Merganser (female and male)
Several pairs of Wood Duck have been visiting the beaver ponds lately. Males and females have been checking out our Wood Duck nest boxes as well as many of the larger woodpecker holes around the beaver ponds. It's a strange thing to see a duck way up in a tree, but if you do see one, and you're in the Northeast, it's most probably a Wood Duck. Sometimes the male will find a tree cavity that looks promising, and, much like the Bluebird, he'll call his mate over to see it. His call is a thin high pitched whistle and perhaps is a bit undignified for such a majestic looking bird. Other times it's the female that takes the initiative and she comes up with the most promising nest site. Either way, it will be her job to lay the eggs, incubate them and then, if all works out, raise the ducklings. After mating, the male abdicates all domestic duties. He may just be too pretty to work. I’m afraid that that makes him a bit of a dead-beat dad, but he’s by no way alone in the world of ducks.

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