In 1996, 2 additional potential Chimney Swift nest sites were erected at the Mansfield Dam Bird-banding Station as part of the North American Chimney Swift Nest Site Research Project: one measuring 11" x 11" x 8' and another in the shape of a vertical prism measuring 24" x 24" x 24" x 8' tall.  Along with the original "Twin Towers" (erected in 1989) and the cinder block "Castle" (erected in 1994), this brought our total number of sites to 5.

The smallest of the test structures (11" x 11" x 8') was installed on a lower terrace of the canyon approximately 40' below and 200' from the Twin Towers.  The prism test tower was installed mid-way between the Castle and the Twin Towers. By late May, nests were constructed and eggs laid in both of these new designs.  Initially we were very encouraged, but as the incubation period began to stretch beyond the standard 21 days, our optimism began to sour.  The adults in both of the small towers continued to incubate their clutches more than a week beyond the normal period to no avail.  Eventually both towers and the unhatched eggs were abandoned.

The nest failure in the 2 test towers was a disappointment, but a learning experience as well.  The nests in both structures were constructed on the northern walls and not low enough to avoid direct sunlight in the middle of the day.  The swifts do not begin their incubation until the next to last egg is laid.  Consequently the first eggs when exposed to direct sun were literally cooked. An identical test tower at the Driftwood Station was successful and fledged 4 young. The nest in this tower was located on the southern wall where it was never exposed to direct sun.  We believe that direct sun -- and not internal tower temperature - was responsible for the failure. 

We had assumed that instinct  would guide the swifts in optimum nest placement.  Perhaps this is a learned skill.  In an attempt to prevent future nest failure due to direct sun exposure, 2 of the test structures have been fitted with a sun-shade on the top, south side.  The successful mini-tower at Driftwood will not be altered. 

Although one of the original "mini-towers" (11" x 11" x 8') was used successfully by swifts in 1996, we are recommending several modifications to any of these or similar structures which are already in place.

The shorter  the structure, the less dark it is likely to be, and darkness is a consideration for swifts when they select a nest site.  The original mini-towers had only a wire-mesh bottom.  A solid bottom with several 1/2" ventilation holes is now believed to be an improvement to the design.  It has also been recommended that the interior walls also be darkened since the textured 1-11 plywood is light in color.   Because paint might cause out-gassing which could be harmful to the birds and also smooth some of the texture required, a propane torch might be used to lightly char the wood.  A sun shade on the top southern edge may darken the interior and reduce heat build-up as well. 

A home video from Jerry Koch in Monnett, MO. suggests an even more radical approach.  He observed swifts entering a small side opening on a chimney.  This particular chimney was completely protected form the sun and rain.

Another solution to darkness and protection from the elements may be a chambered structure.  That is, a small, short column (4' or so) on a larger, offset bottom.  Two different versions of this design were installed in 1996, but too late in the season to be used by swifts.

All of our large towers have been built with a 1 1/2" air space between the inner and outer walls.  Most early small models have all been single-walled.  Several more seasons may be needed to determine if the insulating air space is necessary to hold internal temperatures at acceptable levels.

Although concrete and cinder block make an extremely permanent structure, our experience with the Castle nests would suggest that untreated masonry may be less than ideal.  Hopefully the water-based sealer we are experimenting with will solve this problem.  If it does, concrete culvert pipes may provide a ready-made option for Chimney Swift housing.  They are  pre-cast, reinforced and available in a variety of sizes ranging from 12" to several feet in diameter.  Their obvious limiting factor is their considerable weight.  Also, some type of drainage would have to be provided in the bottom, or they would fill with water.

Finally, Jack Freeman (see more about Jack below) suggests making texture on smooth surfaces by applying  some material with a toothed trowel.  Once dry, the ridges would provide an excellent foot hold and nest anchor for Chimney Swifts.

We thought the Twin Towers and the Castle were the fanciest Chimney Swift houses since Althea Sherman's tower until we heard from Jack Freeman in Springer, Oklahoma.  Mr. Freeman has apparently been catering to the needs of swifts in ways we had not imagined.  During the intense heat of this past summer, he installed a small fan in the bottom of his tower to help cool the birds.  He is currently working on a rain deflector to be installed inside the tower just above the nest location.  He notes that it should be large enough to channel water on the wall away from the nest without being too large for the young to be able to climb over.

Jack is one of those rare folks who enjoys the sounds made by his swifts.  So much so, that he has installed an intercom in the tower so that he can monitor every note.

The Johnson County Songbird Project has overseen the printing of a new edition of  Althea Sherman's Birds of an Iowa Dooryard.  This paperback edition has some of Ms. Sherman's beautiful artwork which was not in the original, and is a great addition to any personal or community library.  Proceeds from the sale of this enlightening and entertaining ornithological study will be used to restore the original 1915 Chimney Swift Tower.  At the modest cost of  $15.95 (postage included),  it also makes a great gift.  To place your order, contact the Johnson County Songbird Project, 2511 HWY 1 SW, Iowa City, IA 52240.  For more information contact Barbara Boyle at 319-628-4824.

I hear a lot of birds in my chimney.  How many nests are in  there?

Probably only one!  Although Chimney Swifts will congregate in large flocks (sometimes hundreds or even thousands), they are solitary nesters.  A pair will vigorously defend a nest site.  However, they do allow a few "helpers" to join them after the nesting has begun.  These extra birds are most commonly birds which were  hatched there the previous year.  Three or four hungry baby Chimney Swifts can sound like a dozen.  It is dark in a chimney, and the young birds rely on their impressive voices to "remind" their parents where they are.

Are the nests likely to stop up my chimney and cause a fire hazard?

Not at all.  Since only one Chimney Swift nest is built in a chimney each year and each is only about 3" across, it would take dozens of years of neglect for any build up to occur.  Chimney Swift nests are not the bulky, soft nests like those of the House Sparrow which many people are used to seeing.  They are built of tiny twigs which swifts glue together with their own glue-like saliva.  In fact, some tests had indicated that the saliva acts as a fire retardant.  An annual chimney cleaning is important for home safety whether or not there are swifts in residence.

If  birds live in my chimney, how can I use my fireplace in the winter?

Chimney Swifts are not in North America during our winter months, so there is no conflict in sharing our chimneys with them.

Where do Chimney Swifts go in the Winter?

It was learned earlier this century that some Chimney Swifts winter in the Amazon Basin of Peru.


When do the Chimney Swifts come back?

In Central Texas, the swifts return in late March.  In your area?  You tell us!  When is your first sighting?  Contact us at:   DWA@austin.rr.com

Chaetura is a publication of the Driftwood Wildlife Association, a non-profit all volunteer organization supported by tax-deductible contributions.  DWA is dedicated to promoting research and providing community education in the areas of wildlife rehabilitation and avian natural history.  Copyright, Driftwood Wildlife Association, 1997.  All rights reserved.

We wish to express our thanks to the following organizations for publishing information and articles about the Nest Site Research Project in 1996:

Texas Parks and Wildlife Magazine, North American Bluebird Society, Johnson County Songbird Project, The Austin American Statesman, The Humane Society of the United States, Alabama Ornithological Society,  Travis Audubon Society, the Missouri Conservationist, and the Pensacola News Journal