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Weather conditions in 1998 were extremely hot and dry. The drought proved advantageous to the breeding swifts by eliminating the moisture which often causes their nests to peel away from the nest site wall. However, the excessive heat took a toll on nestlings in 2 of our experimental towers.
During June, temperature rose steadily from the mid 90's to a record high of 108° F on June 14th. From that date until August 15th, there were only 4 days on which the high temperature was less than 97° F. Of those 63 days, 30 registered 100° F or higher.
The eggs which were laid in the uninstalled Garden Tower literally cooked in spite of the sun shade which had made the mini-tower successful in 1997.
In March of 1998 a protective "second skin" was installed on the Prism. This modification made the experimental tower successful for the first time since it was erected in 1996. However, when the pair of swifts nesting in the Prism attempted a second brood, the young succumbed to the relentless heat during a stretch of 100° F + days.
In stark contrast to our negative results with small, single-walled towers at the Mansfield Dam Bird Banding Station, the Driftwood Bird Banding Station had a successful Chimney Swift nest in their uninstalled mini-tower for the 3rd year in a row. This tower is mounted on a deck approximately 3 stories high where the constant breeze apparently keeps the structure cool enough to compensate for even the most brutal of Central Texas summers.
Although the small mini-tower has been consistently successful at Driftwood, we must caution that this style of diminutive Chimney Swift house is very susceptible to overheating. Based on several years of testing, we must recommend against single-walled, uninstalled towers -- at least in the South.
In 1998, a miniature security camera was installed in the viewing port of the South Tower. It measures only about ½" in diameter and is about 3" long. Some of the fledglings were curious about the camera and climbed up to peer directly into the lens - making for interesting and humorous viewing. For the most part, the swifts seemed oblivious to the camera. The resulting video tapes of activity in the tower provided new insight into the swifts' behavior at the nest as well as interaction with "intruders" which happened into the tower. We have plans to install a camera in the North Tower in 1999. Comparisons of the behavior of birds in the 2 towers and observations of roosting flocks should prove interesting.
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