Chimney Swift Towers: New Habitat for America's Mysterious Birds

Monitoring Roost and Nest Sites

Building Chimney Swift Towers 84 Monitoring Roost and Nest Sites WE OFTEN SAY that observing Chimney Swifts is “a pain in the neck.” This is literally true because most of their activity takes place high above treetop level. One must be constantly looking up to observe swifts’ “kiting,” “V-ing,” “cracking-thewhip ,” “parading,” and feeding maneuvers. If observing Chimney Swifts in the open sky is difficult, directly observing them in the nest or roost site is nearly impossible. Even if direct access is possible, too much interference (or any interference at the wrong time) may cause the swifts to abandon the site. This is certainly the case if the swifts’ activities are disrupted during their site selection or nest-building activities. Frightening an incubating bird from the nest may cause eggs to be destroyed when accidentally knocked over the edge. Any intrusion into a nesting chamber containing young swifts can cause startled nestlings to fall to the bottom of the site, resulting in injury. If older nestlings are prematurely flushed from the site, they will not survive. Fortunately, there are several ways to know what is transpiring in a chimney or tower without ever looking inside while the swifts are in residence. Actually seeing a single Chimney Swift enter a site during the day is a chance event at best, especially early in the season. The best time and place Monitoring Roost and Nest Sites 85 to observe swifts around their home is at dusk and from a distance. If swifts are suspected or known to occupy a structure, patiently and quietly observe from at least thirty feet away. Begin observing approximately thirty minutes before sunset. Most weather forecasts include time of sunset in their daily report . Pair bonding begins soon after the return of the swifts to their breeding area from their South American wintering grounds, so groups of two to five or more birds will fly in tight formation, uttering their staccato, chippering vocalizations. A mated pair will reveal themselves when they both snap their wings up into a stationary “V” position and glide one behind the other. Swifts will generally make several passes and circle the structure before entering. Many birds have unique postures when tumbling from the sky, which can be very entertaining for the observer. Roosting structures may contain as few as a dozen or as many as several thousand Chimney Swifts. Generally, roosting birds arrive in “waves.” The first arrivals will circle the area, foraging and vocalizing before entering. Additional birds will continue to arrive, circle, and enter the structure as dusk falls. Observers who are interested in counting swifts should monitor the sky until dark, counting individual birds as they enter the site. We have found that a hand-held athletic lap counter works well for counting individuals in roosts of up to two hundred birds. Larger roosts require some estimating. An effective method is to count birds in fives or tens as they enter a site. A lap counter can still be effective. The number indicated on the counter can be multiplied for a reasonably accurate estimate. Chimney Swift vocalizations also offer aid in determining the activity in and around a structure. Building Chimney Swift Towers 86 Inside a nesting structure, mated birds will utter soft chippering calls. Occasionally, the sound of their wings as they fly up and down the interior can be heard from outside. Very excited and loud chippering accompanied by a clapping sound as the swifts snap their wings usually denotes aggression or a territorial dispute. Nestling swifts produce at least two different calls, which usually become audible from outside the structure after the birds reach ten days of age. The raucous chatter they produce each time an adult enters indicates that the young are being fed. A mechanical, rasping call indicates fear or agitation . Hearing either call indicates an active nest. These sounds will cease after the young have fledged: approximately eighteen to twenty days after the sounds are first audible. After Chimney Swifts have migrated from the area in the fall, an inspection of the bottom of a nest site can be very informative. The shear volume of droppings can indicate whether the site was occupied by a few or many swifts. When dried, the average droppings produced by a family of five or six Chimney Swifts during their summer stay will fill a one-quart plastic bag. Also...