There are few birds more at ease in the air than swifts, streamlined, with unique adaptations for a life on the wing.
The swifts belong to the family Apodidae, which consists of 19 genera and 112 species. Here in North America, four species of swifts can be found. In the east, you will see the Chimney Swift, and in the western half of North America you can see the White-throated Swift, Vaux’s Swift and the Black Swift.
The name Apodidae comes from the Greek word apous, which means footless, a reference to their tiny legs. If you take a look at many art pieces depicting these birds in the past, you will notice that many times they wont even possess feet or legs.
While these birds look very similar to swallows, they are actually not closely related, more so they share similar appearance due to convergent evolution since both have really aerial habits and both have the need to catch and eat insects in flight. It is actually believed that the treeswifts are the swifts closest relatives. Who both in turn are believed to be a sister group to the hummingbirds. Both groups spend most of their lives airborne.
Everything about these birds are made for life on the wing, and they pretty much do spend almost their whole lives in the air. Only landing to nest or with some species, roost for the night. All species in this family have an extremely similar body shape and size. From their aerodynamic bodies, which are thin, long and tapered, to their long thin swept back wings which resemble a crescent or boomerang. Their bills are small, pointed but lead into a large gape that reaches back to below their eyes and is generally surrounded by rictal bristles to help catch insects. This wide mouth is also perfect for catching insects.
Some species have short squared tails while others can have long deeply forked tails and others can vary anywhere in between. The Cassin’s Spinetail has such a short tail that it appears as if it doesn’t even have one. And on the opposite end you have the African Palm Swift whose deeply forked tail makes up almost half of its body length.
If you look closely at the tail of several species, you will notice that many have sharp needle-like projections on them. These little spikes help them to prop themselves up when they cling to vertical structures, all the while protecting the rest of their tail feathers from getting damaged from the wear. These little projections have also led to several swift species being labeled as spinetails.
Their feet and legs have also evolved for their lifestyle, with not much use for them, they have become small and short, many species, because of these small apendanged, cannot even take flight from the ground. Their claws though are very sharp, curved, and have three forward facing toes and one backward. These claws and foot alignment are perfect for gripping vertical surfaces.
Most species in this family are various shades of brown, light, dark or mottled. Many species can have white patches on their bodies, whether that be on their throat, underside of their wings, on their rump, breast, belly or as a collar around their necks.
The most colorful bird in the swift family is the Purple Needletail. This swift that called the Philippines home, has a black body that has a purple wash to it with a white horseshoe mark near its vent and white lores. This swift is pretty scarce though, leading to not much being known about this bird including its diet and breeding biology.
The largest in this family is the Alpine Swift, which is up to 9.1 inches long with a wingspan of up to 22 inches wide. This swift can be found in Africa, southern Europe and Asia. On the other end of the size spectrum is the Pygmy Swiftlet, who is the smallest in this family. Their wingspan measures about 3.5 inches long. Though if you live in North America, the smallest swift species you will see is the Vaux’s Swift, who has a wingspan of about 12 inches.
Their skeletal anatomy is also interesting, especially if you inspect the bones in their wings. The bones nearer to their wingtips are proportionally greater than compared to other birds. This anatomy can also be seen in Hummingbirds. This bone structure gives them more maneuverability and stability, allowing the wing to rotate at the base all the while allowing the wing to stay rigid and fully extended.
Sifts can be found in every continent except Antarctica. Though they won’t be found too far north, in larger deserts or out in the ocean or distant islands.
Those found in temperate regions migrate, as there will be no available flying insects in the colder times of the year. During this colder time, they will migrate south to more proposal regions. Many species in this family are migratory to some extent. A fine example of this can be seen in the Common Swift, who can travel 124,274 miles in a year. They have a very characteristic flight style, their wingbeats are very rapid and shallow, often including quick turns and steep altitude changes, this flight style can also help you tell if a bird way out in the distance is a swift or a swallow.
Everything about this bird is made for the air, and from that, they also have speed. The Common Swift has been recorded flying at 69 miles an hour during its mating flights, which are also called screaming parties. This speed makes it the fastest level-flight of any bird in the world. It would also have been the overall fastest level-flight flier if it wasn’t for the Brazilian free-tailed bat.
While they rely on warm weather suitable for flying insects, if there is a sudden cold snap, swifts are able to enter a state called torpor, where they lower their body temperatures and go into a hibernation-like state to preserve calories and hopefully survive til the weather turned more favorable, this is only for very short periods of time though.
Most swifts are highly social and tend to roost in a colony, with some roosting colonies of Vaux’s Swift containing up to 35,000 individuals.
Another cool adaptation that some species can have is a simple form of echolocation to help them navigate in dark caverns where they may be roosting or nesting.
As to be expected, swifts feed almost exclusively on flying insects and arthropods that they catch and eat on the wing. Some of the insects they will prey on are flying ants, aphids, bees, dragonflies and flies. To eat and find enough food for young, they often will travel quite the distance away from their nests.
Swifts, overall, are monogamous with both the male and female providing care. Just like swifts are different, so are their nests. Their nesting location varies by species, some will nest in caves, some under eaves of buildings and bridges and some construct their nests in hollow trees.
These cup-shaped nests can be constructed, depending on species, out of mud, sticks, feathers, or various plant materials mixed with their saliva. Their saliva is sticky and acts like a glue to adhere their nest to walls or the face of a cliff. These nests being constructed on a flat surface is also advantageous as it gives the swift an easy way to land or take off into the air as well as offering added protection from most predators. In each clutch, swifts will typically lay one to five eggs each. These eggs will then typically be incubated for two to four weeks and the hatchlings will be cared for for another six to ten weeks.
The Edible-nest swift can make its nest entirely with its own saliva though, which as its name suggests, is the basis for bird’s nest soup, a recipe that has been in use for over 400 years in China. It has been found that these nests are constructed with strands of interwoven saliva, along with high levels of calcium, iron, potassium and magnesium.
Another interesting nest example is from the African Palm Swift who uses its saliva to basically glue its eggs to a vertical wall.
Of the 112 species of swifts in the world, 11 are threatened. These 11 species also happened to all be swiftlets belonging in the genus Collocalia and Aerodramus. Many of these species are endemic to islands and are already disadvantaged from having small populations. Of these 11, six are Near Threatened, four are Vulnerable and one is Endangered.
Some of the threats these birds are facing are introduced predators such as brown tree snakes, and habitat loss, and from the collection of nests for food and medicinal purposes.
The Chimney Swift is a member of this family that can be found in the eastern half of North America (and also has the nickname of a flying cigar due to their body shape), and unfortunately it is also a species of concern, which it’s population estimated to have dropped by half since the 1960s. It’s main issue, loss of nesting locations. Originally, these swifts would nest and roost in old hollow tree stumps, but as old forests were cleared these locations vanished, so they in turn started turning to chimneys and other buildings. Though now, many buildings don’t have chimneys, and if they do they are capped or unsuitable for them. To help this bird, efforts are being made by various organizations to build chimney swift towers, which provide a nice alternate artificial place for these swifts to nest and roost.
So what are some ways you can help your local swift species. As for swifts and any insect eating birds, one important thing you can do is not use pesticides and chemicals in your yard, bugs after all, are an important food source for many species. The more bugs, the more food for birds, and the more bugs, the more successful a bird can be to raise more baby birds which equals more birds!
Another way to help swifts is to research your local species and see what it requires for nesting and/or roosting and think about building one of these structures for them or even donating money to sponsor the construction of one of these structures by your local bird advocacy group.
References/ Further Reading