Neat Stuff About Birds In The Chattanooga Area
by Riverwalk Birding Club
posted July 15, 2008
House Wren
The House Wren looks like the Carolina Wren without the stripe thru its eye, other than that it is about same size, shape and color, but its nesting habits differ greatly. As part of the courtship process, territorial males construct multiple nest within their territories in almost every available cavity. One or two females will inspect the nest cavities and select one to complete the nest. When a male House Wren claims a cavity for nesting he begins bringing small twigs. He may put more than 400 twigs into one cavity. When a male pairs with a female she will take over nest building and adds the nest cup and lining.
The Riverwalk Bird Club has a bluebird trail on Greenway Farm consisting of 26 nesting boxes, club members Bob & Shil Lewis monitor this trail and keep the nest boxes clean. This year they found a House Wren nest in box # 13, they also found a House Wren nest in box #19 plus several small twigs added to three other boxes. The Wrens nest in box #13 was the real nest with eggs and fledgings, the one in box 19 was a false or dummy nest, built by the male to attract a female. After nesting season was over we decided to count the twigs in box #19 to see if it was possible for the Wren to place 400 or more twigs in it.
The entry hole is 1 & ˝ inch, the inside of the box is 5 inches by 5 & ˝ inches and it is 10 inches from floor to roof. The entry hole and side vents were stuffed with small twigs. We took the box down to photograph and count the twigs to be sure we got an accurate count.
We removed the roof and could see the nest cup in the top back side of the box, we also noticed that the wren had to squeeze past the twigs in the entry hole then climb up and over twigs inside to reach the cup. Every twig was placed in a certain spot, they were not just stuffed in the box, they were woven together.
We then removed the side of the box, you could see that the twigs filled the box from top to bottom, it also had several spider nest bags woven into the nest. Again you could see that each twig was placed where it should be to form the nest cup,
We then very carefully removed the nest from the box , it came out in square shape. We noticed that everything in the box was a small twig, all sizes and shapes, most looked like oak twigs, some less than one inch long. Bob & Shil took the nest home to very carefully take it apart and count each twig in small piles.
The twigs were counted into piles of 10 twigs, the small piles were tallied for a grand total of 1304 small twigs. This total was hard to believe.
All the twigs were then placed in a shoe box.
Some interesting things to think about;
Over 1300 twigs require 1300 trips to locate them.
Each twig must be taken in the nest thru a 1 ˝ inch hole.
The Wren must know that the twig will fit before taking it inside.
Twigs in the side vents may have been pushed in from the outside.
Some twigs had a small fork too wide for the entry opening so they must go in so the fork will close as it goes thru the hole, the Wren had to know this.
1304 twigs were in this box #19, the Wren built one more nest in # 13 and several part nest in other boxes, this requires a lot of work plus engineering skill. Thanks to Bob & Shil for a good job, also Charles Dean for his photo of a House Wren.
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