A Peek into the Life of a Chimney Swift

Mark Armstrong, master bander of both songbirds and hummingbirds, and his wife Janie Kading, have a chimney swift tower that Mark constructed in their back yard   

For several years swifts have nested in the tower.  Small holes are drilled in the bottom of the base so that you can look up and actually see how many nestlings have their heads over the nest edge and how many swifts are roosting on the chimney wall.

This breeding season a pair of chimney swifts raised at least three young in the tower. The nests are shallow and when considering its small size, it is hard to imagine how three nestlings can fit into it.  Both the male and female bring sticks to build the nest, breaking them off with their feet and carrying them to the nest site in their beak.  The twigs are then sealed with sticky saliva from the swift's seasonally enlarged sublingual glands

Even more fascinating is the description found in the account of Birds of North America notating the timing of egg-laying.  "Egg-laying begins when nest half-finished at about 3-6 d, and new twigs and saliva added during incubation...."  The pair stops adding sticks shortly before the eggs hatch.

On July 1st, Mark and Jane set up traps to capture and band hummingbirds in their yard.  In addition, to the hummingbird traps, a mist net was set up to capture hummingbirds and possibly a swift as it left the tower after feeding young.    

Above, you see the band being attached to a swift's leg.  A swift's feet and legs are weak, similar in structure to those of the hummingbird, and are used for gripping and grasping but not for perching.  The chimney swift is airborne most of its life and uses its sharp claws to cling to vertical surfaces while roosting.  Also, notice how long the wings are in relation to the body.

The swift's interesting tail structure also is clearly an additional support while roosting. The feathers end in sharp barbs that help to support the bird while clinging to the roosting surface.  

Below you see two adult swifts resting after feeding young in the nest.  Though the image is not exceptionally clear, you can see that the birds are not just clinging with their feet but are using their tail as support while resting.

After the young fledged, other swifts in the area joined the family in the tower at roosting time and as many as 15 were counted before all the swifts departed on migration.  Presently, swifts are migrating through our area and known communal roosts are being monitored to count the number of swifts as they enter the chimney. The highest count from one chimney that I've seen reported to date was 10,000 in the Nashville area (reported last week).

Links and Resources:

Chimney Swifts coming to roost during migration
Chimney Swifts
Mark Armstrong also banding hummingbirds
Swift Night Out
Chimney Swift Tower
Knoxville Chapter, Tennessee Ornithological Society
Tennessee Ornithological Society