Wednesday, July 25, 2012

What's inside that birdhouse?

Eastern Bluebird nest.  The chick is only a few hours old.

One of the many fun things I get to do as a Field Ecologist with CES is checking the nestboxes on Chino Farms/CRFRS.  There are about 100 boxes spread out over several miles of roads and trails.  More or less once a week from mid-March through August someone checks each box and records what is inside.  Usually, that someone is me.  Most of the time it’s an adventure to make the circuit-  I run into Bluestem Farms staff, I watch an Osprey catch a fish, I hear the wheezy call notes of Blue-gray Gnatcatchers, I admire the flowers in bloom. Did I mention this is my job? 
Carolina Chickadess back in the nest after having been banded.

I keep a record of what is in each box all season. I band the chicks when they are old enough and when they have fledged the nest, I remove it so the box is ready for it's next residents.  Each box is a surprise- I never know what will be inside!  A box that was empty last week could have a full nest this week.  A nest that last week had chicks could be all torn up with no birds to be found.  Most of the boxes are used by Tree Swallows and Eastern Bluebirds.  Less frequent residents include Carolina Chickadees, Tufted Titmice, House Wrens and Great-crested Flycatchers.  Sometimes the birds banded as chicks stay on the property to breed as adults.  There are several old titmice and bluebirds still around that hatched in one of our boxes.

Of course, a sturdy, water tight cavity is prime real estate to many animals and not all visitors are birds.  Several boxes host Flying Squirrels which we allow to stay.  Mice are frequent squatters and we try to discourage them.  Sometimes, a birdhouse with eggs inside is a boxed lunch for a raccoon or opossum or a snake.  Everything needs to eat.
Young Black Rat Snake inside what had been a bluebird nest.
Mice like our birdhouses quite a bit.

The Tree Swallows have finished nesting for the season, but there are still 3 boxes with House Wren nests and 7 with bluebird nests.  Bluebirds can nest quite late into the summer.  The latest we’ve had a bluebird fledge on Chino was September 6th!  Looks like I have weeks of nest checks still ahead of me.  I don’t mind.

Maren Gimpel is a field ecologist at the Chester River Field Research Station.  Photos and stories about the goings on of CRFRS can be found at or at

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