Vaux’s Swift

A dark and small bird of the western half of North America, the Vaux’s Swift is the smallest Swift in North America and are very similar to their eastern counterparts, Chimney Swifts. They spend a majority of their day in the air as they hunt for small insects and spiders. Like most other swifts, they are fiercely agile and are capable of numerous acrobatic stunts to aid them in their hunts. They are also extremely quick, often chasing after flying insects and catching them mid-air.

About Vaux’s Swifts

These birds spend very little time perched and spend even lesser time on the ground. The only times they choose to perch are when they are nesting or roosting. Their preferred locations for nesting are usually within hollow trees in old-growth forests, making them extremely vulnerable as deforestation has destroyed a majority of their nesting habitats. Although they sometimes use unlined chimneys to nest in, it is not a practice that is as common when compared to the closely related Chimney Swifts. Like other swifts, their saliva has gluelike properties to it, which they use to build nests.

This species was named after the 19th-century naturalist William S. Vaux, who was a friend of the renowned ornithologist, John K. Townsend. Unfortunately, many aspects of their lives are still poorly understood due to their reluctance to ever coming on land. Thus, the topic for today is going to be Vaux’s Swifts.

● Vaux’s Swift Photos, Color Pattern, Song
● Vaux’s Swift Size, Eating Behavior, Habitat
● Vaux’s Swift Range and Migration, Nesting

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Vaux’s Swift Color Pattern

Vaux’s Swifts have plain grayish-brown bodies that sometimes have a slight green iridescent sheen to them. Their rump and the feathers on the upper portion of their tail are similarly pale brownish-gray with a duller shade of the same color on the back. The upper breast and the throat are markedly paler than the rest of their undersides, while their tail is sometimes lighter due to the wear and tear experienced by the birds during nesting and roosting. The faint green iridescent sheen is present only in birds that have a fresh plumage, before gradually turning into a bluish or a purple sheen as the birds’ age. These birds do not exhibit sexual dimorphism, with birds of both sexes looking similar to each other in plumage. Juveniles resemble adults but have thin whitish fringes on their wings that wear off with
age. Their bodies are also darker and have more blotched patterns to them.

Description and Identification

Since these birds are almost always in the air, the best way to spot them is to look up at the treetops of mature coniferous forests. Old-growth forests harbor most of their populations, with the birds mainly going towards regions with lots of flying insects. Forest openings, edges of waterways, and burned areas are also popular regions for spotting these Swifts. Sometimes, they gather to roost in chimneys as well. During the winters, these birds go towards Central and South America and settle in similar habitats.

Vaux’s Swift Song

Although Swifts are not known for their vocal ranges, Vaux’s Swifts have a very limited vocal range even for Swifts. Although their calls are understudied, the ones that have been studied give the impression that they are not the most vocal birds. The most common call is the buzzy insect-like twitter call that they give out while in flight. It is high-pitch and consists of rapid chipping sounds. Their calls are very much like those of Chimney Swifts, but also include a variety of high-pitched squeal-like sounds that usually quickly drop in pitch. Since these vocalizations are more common during the breeding seasons, it is difficult to determine their vocal patterns during the other times of the year. Nestlings give a series of raspy notes in rapid succession, similar to the begging calls of many other species.

Vaux’s Swift Size

Vaux’s Swifts are the smallest Swifts in North America. They have a body length of 4.3 inches and an estimated weight of 0.5–0.8 ounces. Their wings are extremely narrow and swept back, with a wingspan of 11 inches, their wings curve along with both leading and trailing edges. These proportions make them larger than Anna’s Hummingbirds and smaller than a Barn Swallow.

Vaux’s Swift Behavior

Vaux’s Swifts spend most of their lives in the air. They fly constantly unless they need to perch to nest or roost. They fly at all heights, from gliding low to the ground to high over the treeline. Vaux’s Swifts don’t walk or hop but sometimes perch on vertical walls to nest and roost. They are able climbers but prefer flying more. Their flight often seems fluttery, stiff, and extremely quick, patterns that are usually observed in flocks or in pairs.

These Swifts are most likely very aggressive during the breeding seasons, often engaging in chasing intruding Vaux’s Swifts away from their territories. However, it is difficult to ascertain if they are truly territorial due to the lack of data. The similarities between courtship chases and aggressive chases make it hard to tell whether these birds are as aggressive as other shorebirds. Since they sometimes nest in small colonies, they are not the most territorial shorebirds.

These birds are monogamous as two Swifts occupy a single nest. Pairs also nest together for multiple years at a stretch, although it is unclear if this behavior is applicable to all birds. Small colonies of these birds gather and nest together in a single tree, indicating that they are not particularly territorial. Vaux’s Swifts also roost in large communities of large flocks, making them a sight to behold in many parts of their range. Thousands of Swifts often gather to roost together.

Vaux’s Swift Diet

These birds forage while in flight, feeding on tiny insects and spiders that they catch in the air. They mainly feed on flies, hoverflies, ants, booklice, leafhoppers, bees, aphids, leafhoppers, planthoppers, lanternflies, spindlebugs, moths, bark beetles, moths, mayflies, and true bugs. They may forage in large flocks, pairs, or individually over their primary feeding territories. Sometimes, they flutter and stall over the tips of tree branches to glean insects from the bark. Young swifts are primarily fed insects, with the adults capturing over 100 insects and spiders. Adults chew these insects up and feed the chicks through regurgitation at the nest to make it easier for them to digest.

Vaux’s Swift Habitat

Vaux’s Swifts can be found using mature and old-growth coniferous and mixed forests for nesting, preferring hollow trees that give them suitable nest sites. Forests with coastal redwood, ponderosa pine, grand fir, western hemlock, western redcedar, and Douglas-fir have the largest numbers of these Swifts, where they tend to produce more nesting and roosting cavities than other species of trees in the same regions. Trees used by these Swifts in their wintering grounds also include hollows, where they typically roost in along with their flocks. Old Woodpecker holes are also used by these birds as entrances. They settle in forests of a variety of different elevations, in both their breeding and wintering grounds. Sometimes, they use unlined chimneys and natural limestone wells for roosting and nesting as well.

Vaux’s Swift Lifecycle

The number of broods that these swifts have in a single year is unknown, but it is presumed to be one. Each brood has a clutch size of 3–7 white eggs, with both members of the pair taking turns incubating the eggs for 18–19 days. Sometimes, one or two extra adults may help the parents incubate the nests and feed the nestlings later on. Once the eggs hatch, the chicks emerge completely naked and helpless. Both parents tend to them and feed them every 12–18 minutes, but the frequency of their feeding visits decreases as they get older. The young ones learn to fly after 28–32 days but may return to the nest site for roosting for several more days until they go their own way.

Nesting

Vaux’s Swifts are known for their preference of building their nests within hollows of live or dead trees. They generally prefer old-growth or mature coniferous trees but may sometimes settle for unlined chimneys or under rooflines. They are also known to accept manmade nest boxes when available. Information about which member of the pair makes the final selection regarding the nest site is still unknown.

The construction of the nest is carried out by both members of the pair, with males and females gathering the materials and making a cup out of twigs. Their glue-like saliva is used to make the twigs stick to each other. The nest itself looks rather sloppy and is semi-circular in shape. Sometimes, other softer plant material is also used in creating the nest. The resulting proportions of the nest amount to the outer cup being 4 inches across and 2.4 inches tall, with the interior cup 3.2 inches across and 1.2 inches deep.

Anatomy of a Vaux’s Swift

Vaux’s Swifts are the smallest swifts of North America. They have a body length of 4.3 inches and an estimated weight of 0.5–0.8 ounces. Their wings are extremely narrow and swept back, with a wingspan of 11 inches, their wings curve along with both leading and trailing edges. These proportions make them larger than Anna’s Hummingbirds and smaller than a Barn Swallow.

Final Thoughts

The total numbers of Vaux’s Swifts have reduced by an average of 1.8% every year since 1968, resulting in a cumulative decline of nearly 60%. Common threats that negatively impact them include modern forestry practices that eliminate the old-growth forests these birds are so dependent on. Eradication of their breeding grounds has slowly but surely reduced their numbers by a large margin. In addition to that, these birds are facing severe declines for reasons that commonly impact aerial insectivores.

Vaux’s Swifts are declining at a drastic pace. Their aerial lifestyles mean that it was never easy to study them, but the chances to understand them better simply continue to reduce with every passing day. If adequate environmental precautions are not taken in time, we may lose out on understanding these lovely birds forever.

Ornithology

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Bird Watching Binoculars for IdentifyingVaux’s Swifts

The most common types of bird watching binoculars for viewing Vaux’s Swifts are 8×21 binoculars and 10×42 binoculars. Bird Watching Academy & Camp sells really nice 8×21 binoculars and 10×42 binoculars. You can view and purchase them here.

Vaux’s Swift Stickers

Stickers are a great way for you to display your love for bird watching and the Vaux’s Swift. We sell a monthly subscription sticker pack. The sticker packs have 12 bird stickers. These sticker packs will help your kids learn new birds every month.

Bird Feeders For Vaux’s Swifts

There are many types of bird feeders. Bird feeders are a great addition to your backyard. Bird feeders will increase the chances of attracting birds drastically. Both kids and adults will have a great time watching birds eat at these bird feeders. There are a wide variety of bird feeders on the market and it is important to find the best fit for you and your backyard.

Bird HousesFor Vaux’s Swifts

There are many types of bird houses. Building a bird house is always fun but can be frustrating. Getting a bird house for kids to watch birds grow is always fun. If you spend a little extra money on bird houses, it will be well worth every penny and they’ll look great.