Swifts are small birds that are closely related to hummingbirds. They are known for their speedy and acrobatic flight, spending most of their lives on the wing. One of the most distinctive behaviors of swifts is their habit of roosting and nesting inside chimneys and other vertical structures. But why do swifts choose to fly into chimneys?
Swifts are aerial hunters
Swifts are aerial insectivores, meaning they catch all their food while flying. They consume a diet consisting entirely of insects like flies, mosquitoes, aphids, and ants. Swifts are uniquely adapted to feed, drink, mate, and even sleep while airborne. Their short legs and small feet are mostly useless for perching. Swifts need to stay aloft to survive.
Chimneys provide an essential roosting spot for swifts after a long day spent foraging on the wing. Upon returning to the roost, swifts literally fall asleep while clinging to the brickwork. The vertical surface allows them to easily achieve flight again when leaving the next morning.
Swifts nest in cavities
In addition to roosting in chimneys, swifts also use them as nesting sites. Swifts build nests out of twigs, leaves, and their own saliva. The nests are glued to the inner walls of whatever vertical cavity the swifts select.
Chimneys mimic the hollow trees and cliff faces that swifts originally nested in. They provide shelter, safety, and a place for swifts to raise their young. Chimneys have become a substitute nesting habitat as natural cavities have disappeared due to deforestation and development.
Chimneys offer ideal conditions
Chimneys provide more than just a vertical surface for roosting and nesting. Their structure and microclimate are ideally suited to swifts’ needs:
- Isolation from predators like raccoons, snakes, and birds of prey.
- Protection from severe weather events like storms, wind, and hail.
- Darkness for a peaceful rest.
- Moderate temperatures on hot and cold days.
- Good acoustics that allow echo location and communication between swifts.
- Ample space for nests without overcrowding.
For swifts, the inside of a chimney is the perfect home. Structural quirks like crevices, ledges, and protrusions provide ideal roosting spots. The textured surface offers many grip points for the swifts’ claws.
Abundant availability of chimneys
Another reason swifts are attracted to chimneys is their sheer abundance in the environment. Since the advent of industrialization, chimneys have become a ubiquitous part of human infrastructure. This proliferation of chimneys provided swifts with a bonanza of new nesting and roosting opportunities.
Almost every building has multiple chimneys. Cities contain thousands of suitable chimney habitats clustered together in a small area. Swifts congregating in towns can take advantage of this dense network of nesting sites to raise their young.
Threats from chimney reconstruction and removal
While chimneys allow swifts to thrive in close proximity to humans, they also pose some risks. Chimneys require periodic maintenance, repair, and reconstruction. Many old chimneys are no longer used and get removed entirely.
These activities can destroy swift nests and evict swifts from long-held roosting sites. Structural changes may prevent swifts from entering a chimney they formerly occupied. Blocked access to critical chimneys can devastate local swift populations.
Providing alternative nest boxes
To help offset chimney disturbances, conservation groups advise property owners to install specialized swift nest boxes. These small wooden boxes can be mounted on buildings to replicate chimney conditions. Nest boxes give swifts secure new nesting sites if their traditional chimney home becomes unavailable.
If chimney work cannot be avoided during winter months, care should be taken to exclude swifts as kindly as possible. Swift evictions are best done before breeding season starts or after the young have fully fledged and left the nest.
Coexistence through chimney sharing
With some planning and minor inconveniences, swifts and humans can harmoniously coexist while sharing chimneys. Homeowners may hear swifts vocalizing or see nest materials falling into the fireplace. But these issues can be managed by installing chimney caps or cleanout traps.
Accepting a few more guests at the chimney allows swifts to continue their extraordinary aerial lifestyle alongside people. Awareness and accommodation helps preserve chimney-dwelling swifts for future generations.
Conclusion
Swifts fly into chimneys because they provide ideal roosting, nesting, and living conditions. Chimneys mimic the natural swift habitat but in much greater abundance near human habitations. They offer safety, stability, and shelter in a world where old hollow trees and cliffsides are disappearing. With mutual understanding and responsibility, swifts and humans can compatibly share chimney space together.