Wednesday, May 16, 2012

Como Park Bluebird Trail Update: May 16th

Post contributed by Sharon, volunteer Bluebird Trail monitor:

Tree swallow nest with feathers
This week, I did not open four nestboxes, two occupied by bluebirds and two, by chickadees, since the young birds are near to fledging, but perhaps not quite ready.  If I opened the box I might surprise them into jumping (or tumbling) out of the nest too early.
      Three more boxes have a total of 10 bluebird eggs and 1 cowbird egg.  This cowbird egg might successfully hatch as it was laid at approximately the same time as the bluebird eggs.
      One box has 8 chickadee eggs, which should hatch soon.

Tree swallow nest with plastic

      The final two boxes are occupied by tree swallows.  One nest covered in white feathers has some eggs in it, but I couldn’t count how many due to all the feathers.  The other tree swallow nest doesn’t have feathers in it at all, but has many clear plastic wrappers!  This is unusual for tree swallows, and confused me into thinking the nest belonged to house sparrows, who often use trash in their nests.  But last week I suspected the nest might indeed belong to tree swallows since I’d seen one emerge from the box earlier, and the grassy nest material was not messily built up the sides as much as a house sparrow’s would be, so I did not remove the nesting material.  Sure enough, this week there are four white tree swallow eggs in it.