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SOUTH TOWER
The South Tower was occupied the night of March 28 - the first day that swifts returned to the canyon. A single bird roosted from March 28 through April 4 before being joined by a companion. At mid morning on the following day, 3 birds were observed in the tower. Two birds were banded on the left leg, the other was banded on the right leg. A single bird was roosting mid-way in the tower while the other 2 were "engaged" on the floor. Both of the birds on the floor of the tower maintained a firm grip on each other while flapping their wings and wrestling. After a full 7 minutes, the struggle came to an end. The birds separated and clung to opposite walls near the bottom of the tower. After a brief intermission, the left leg banded bird flew at the right leg banded bird which then flew up and out of the tower - closely pursued by the aggressor. This was apparently not a friendly encounter.
Following the excitement 2 to 4 swifts roosted nightly in the South Tower with no further conflict. Nest construction began in the South Tower on April 28. Five eggs were in place by May 16. The following day an egg was found on the floor of the South Tower with a single hole pierced in the shell. Another egg was laid, but the breeding pair delayed until May 22 before settling into regular egg brooding.
The first egg hatched on June 4 and by the following morning 4 hatchlings were actively squirming in the nest. The fifth egg did not pip until 48 hours later. This resulted in an unusual disparity in nestling ages and size. Since Chimney Swifts are extremely attentive parents, the "Little Guy" suffered no ill effects from being stuck on the bottom of the pile. It was fascinating to watch as the parents would withhold food from the larger, stronger and insistent nestlings as they deliberately searched out the smallest of their brood.
A light rain began falling on the morning of June 20. Video observations of the South Tower revealed the parents returning to feed the nestlings much more frequently than normal. The adults were feeding their brood every 5 to 7 minutes as opposed to the normal feeding interval of every 20 to 30 minutes. We stepped outside to discover that the air in the canyon was thick with flying insects. In addition to the rain forcing insects down close to the ground, there was a "bloom" of termites emerging from their subterranean nests. The young swifts were literally stuffed to the point of having the wiggling legs of the termites protruding from their mouths.
Under the attentive care of their parents and tutelage of "Uncle Slug", all 5 South Tower nestlings successfully fledged. The breeding birds were a new pair for the South Tower. One bird was banded as a nestling in the South Tower on June 14, 1998. Its mate was a North Tower parent in 1998. The pair continued to occupy the South Tower sporadically during the day and were occasionally observed roosting together on their nest. However, they did not attempt a second brood. Consistent with the previous 3 years, the Castle hosted a roost from early spring through the fall. On April 14, 43 swifts entered the concrete cinder block structure. A total of 120 very vocal birds were in residence by May 2. The number of residents fluctuated, but continued to average 60 birds throughout the season. The uncommonly tolerant breeding pair managed to construct a nest and lay 5 eggs. Only 2 eggs hatched, but both babies fledged on July 18. No second brood was attempted.
We were amazed to hear begging calls emanating from the Castle in the morning on August 10. The calls continued throughout the next 3 days. Because we are unable to visually monitor activities inside the Castle without opening the door and possibly causing any flight-capable birds to flush, we could not determine the age of the fledgling swifts that now used the Castle as "home". We can only speculate that a nearby family of swifts was "evicted" from their chimney and found the Castle to be a suitable substitute. It would be remarkable for swifts that were too young to be self-sufficient to be competent enough in flight to relocate.
In mid August additional swifts began to use the Castle as a roost. By August 17, 150 to 160 swifts were entering the Castle each night. On August 22 we again heard the unmistakable begging calls of 2 juvenile swifts. The calls continued through August 28. Again we could only speculate that yet another family had been evicted from their home with young birds which were old enough to fly but too young to be completely independent. For the second time in the season the Castle was apparently being used as a "half way house".
Abruptly on September 15 most of the swifts departed from the area. Only 36 birds entered the Castle on that evening. When the Castle flock was captured for banding before sunrise the following morning, only 21 birds remained. Eighteen were unbanded. The 3 others included an HY bird from the South Tower (banded June 22, 1999) and 2 birds that had been hand-reared by us. One hand-reared bird was banded on July 21, 1994. The other hand-reared bird was banded September 5, 1997.
THE PRISM
Two swifts had set up housekeeping in the Prism by April 7. Five eggs were laid and the nestlings successfully fledged. This pair were the only swifts to attempt a second brood on the banding station in 1999. Their second brood consisted of 2 eggs which both hatched, survived the 100 degree weather and subsequently fledged.
THE POOL TOWERS
One of the most common questions asked about the construction of Chimney Swift Towers is: "How close can they be to one another and still be used as nesting structures?" We know that the Twin Towers which are 12' apart have consistently attracted nesting swifts. However, we have never had an opportunity to study towers in closer proximity to one another. On May 6 we began construction of a pair of new cinder block towers. They are situated in a north / south orientation on a level down the canyon wall from the recirculating pools. Both stand on a single concrete slab measuring 80" x 24" and 6" thick. The base of each tower is a U-shaped concrete footing measuring 4" thick, 20" x 20" x 8" tall which is open on one side and fitted with a door for clean out. The actual tower construction uses 4" x 16" x 8" blocks. There are 4 blocks per layer with ends overlapping. This created towers measuring 20" on the outside with an 11" inside diameter and stand 10' 2" tall. The towers are only 26" apart.
By May 19, both towers stood 8' 9" tall. The following morning swift droppings were found on the floor of the South Pool Tower. On May 21st droppings were found in both towers. Construction continued daily with the swifts utilizing both towers overnight. A nest stick was discovered on the south wall of the North Pool Tower (NPT) on May 25th. Our detail work continued with emphasis on the NPT which was completed on June 6th. The swifts continued their nest construction and laid the first of 5 eggs on June 8th. One egg fell from the nest, but the remaining 4 hatched and all 4 of the NPT fledglings were flying in the canyon on August 1st. The South Pool Tower (SPT) received its finishing touches on June 14th. The SPT was not occupied after the nest construction was begun on the NPT.
Chimney Swifts were observed on the station for 209 days in 1999.
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