Thursday, September 23, 2010

Acting Swiftly

"There were many grebes, making spreading wakes in the water as they swam, and I was counting them and wondering why they never were mentioned in the Bible. I decided that those people were not naturalists."
Ernest Hemingway writing of the Sea of Galilee in the Green Hills of Africa.
 The ability of birds to fly has always captivated the human imagination. In our dreams we soar over the landscape with the ease and freedom that by day, we envy in the birds. Vividly can I remember the days when I was a distance runner. On a good day I would glide nearly effortlessly over the countryside. I can no longer do this alas, but the joy of sprinting through the trees and the feeling of physical power was as addicting as anything I have ever experienced. I was confined to the surface of the earth however, any vertical movement I accomplished was dictated by the terrain I crossed. How must it feel to be free of such restriction? To be able to move in any direction, limited only by the speed of thought? I can only dream how it must feel. But Swifts, paragons of flight, need not dream such freedom. They live it.

Every Spring, here in northeast, the Chimney Swifts (Chaetura pelagica) return from their South American home. Briefly, from April to September, we are graced with these aerial masters. The spend nearly all their waking moments on the wing, landing only to roost or nest. They are creatures of the air, and indeed seem to be all wing. Their short, stubby tails and cigar shaped bodies, are eclipsed by long and elegantly curved wings. It is as if the Swifts fly on feathered sabers. To human eyes, which work in very complex ways with our brains, an optical illusion occurs when viewing flying Swifts. We sometimes perceive the wings acting opposite of one another, one being up and the other being down at any given moment, even though they aren't. An oddity created through their evolution and ours.

Long saber-like wings extend well passed the end of the Swift's stubby tail at roost. Note the tail feather's webbing stops short of the end of the shaft, creating "spines" that help the swift perch on vertical surfaces.
Swifts feed on the wing, drink on the wing, bathe on the wing, are believed to engage in play on the wing, and may even mate on the wing. They appear to have no ability to walk or hop on horizontal surfaces, and rarely perch on a branch. They land (or "cling" more appropriately) on vertical surfaces, and can crawl upwards or sideways. They are very social, roosting in large numbers. And according to Swift rehabilitator Jayne Amico,  they are one of the very few avian species to respond positively to being petted. Swifts inhabit our towns and cities, flying over us as we go to work, mow our lawns, go shopping, sit at an open air concert, or any of the myriad of activities that make up our earth-bound lives. Yet the average person knows little or nothing of these winged maestros. Indeed, most birders know little of them as well.

Jayne Amico holds one of the Swifts in her care.

During the breeding season they are found throughout most of the eastern United States, spilling into southern Canada. They evolved to nest and roost in vertical fractures of cliffs, caves, or the hollow carcasses of old growth trees. As mankind altered the landscape by felling the trees and building massive brick and mortar chimneys, the Swifts adapted and moved to these artificial trees, or to large open buildings. Swifts are extraordinarily social, roosting intimately in large groups.They nest as single pairs, but will sometimes tolerate non-nesters roosting in the same chimney. This has led to the erroneous belief that they nest colonially.

Chimny Swift. Photo by Jayne Amico

Within a couple of weeks of their arrival on the breeding grounds, they begin courting or pair bonding behavior. They fly in small groups of a half dozen or less, frequently in sets of three. It may be two males following a single female. It is during these "trio" flights that they display some of their most amazing flying skills, darting at high speed through trees, between buildings, or soaring high into the air. When two Swifts are flying in an apparent bonding flight, the trailing bird will sometimes snap its wings upwards and hold them stiffly still, forming a V shape. This is called "vee-ing", and it is done first by the trailing bird and then often by the the leading bird. Swifts have been observed flying very close together while vee-ing and even appear to be briefly copulating.

Swifts build their nests from small twigs grasped in their feet and broken from trees as they fly. Both birds in the pair do this. These twigs are then cemented in place at the nest site with the bird's sticky saliva, which is produced from a gland that enlarges during the nest building season.

They seem to favor the most sheltered and darkest location in a nesting structure. The eggs are laid when the nest is about half constructed, and construction continues during incubation. Construction completes before the eggs hatch. On average, it takes between two and three weeks to complete the nest.

The average clutch is about four eggs, which are white and semi-glossy.The incubation of the eggs is done by both parents and takes about 19 days. The chicks are altricial at hatching, naked and helpless. Amazingly, their feet develop quickly and they may be able to grasp the wall of their nest site as soon as one day after hatching. The chicks gain mass quickly and reach adult mass after about three weeks.

Feather tracts appear as dark spots under the pink skin at around four days and the feathers erupt through the skin at about one week. The eyes open around week two and fledging occurs at about thirty days. At around nineteen or twenty days, the nestlings leave the net and cling to the nest site wall. While clinging to the walls they spend much of their time exercising their wings. This builds up the flight muscles. Both parents feed the young. There sometimes are "helpers" that assist in the incubating of eggs, and the brooding and feeding of nestlings. It appears these helpers are young adult Swifts, or at least non-breeders.

Once fledged, the young may continue to roost with the adults or join them at communal roosts. The adults no longer feed the fledged young, who are now already masterful fliers. The number of Swifts in a roost can sometimes be very large. The following video is of the closely related Vaux's Swift (Chaetura vauxi), going to roost in Portland, Oregon, but the tornadic roosting flight behavior is the same for Chimney Swift.

These roosts grow as the nesting season ends. When the cool, stable atmosphere of beautiful Fall days come, the Swifts begin their long migration south. Little is known of their behavior on the wintering grounds, in the skies above South America. We in the northeast can only await their return the following April or May.

While they are nesting here in the northeast however, things sometimes go wrong. This is where rehabilitators such as Jayne Amico play a role. Swift nests can be dislodged by heavy rains and fall into people's homes. Or worse, they can be "swept" out by chimney sweeps cleaning chimneys. When this happens, they are sometimes taken to rehabilitators. All too often sadly, the dislodged Swifts are simply put in situations they can not possibly survive. The Swifts in Jayne's care are the lucky ones. She has mastered rearing and releasing these unfortunate individuals, or healing those that have suffered injury. It is far from an easy task, and no one should undertake it who isn't trained and immensely dedicated. I have had the good fortune to witness Jayne in action with Swifts, and I have come to admire her skill, dedication, and love for the birds she handles. I do not think I have ever witnessed the degree of professional knowledge and child-like affection that Jayne exhibits in ministering to her flock. Sorry, I couldn't resist the phrase. The following are a few pictures I took at The Mount Vernon Songbird Sanctuary last July when I visited with my daughter Janet and her friend Emily.

Nestlings in special care at the Sanctuary

Jayne feeds her Swifts in the purpose built feeding "chimney" at the Mount Vernon Songbird Sanctuary.

Four of the Swifts perched on the vertical walls of the enclosure.

Emily and Janet observe Jayne caring for her wards.
Sometimes it is necessary to hand feed individual Swifts that do not adapt quickly to the foreign process of taking food from a human.
Swifts, like many of the bird species in our world, are declining in numbers. There are few or no new chimneys being built that they can use for nesting. Additionally, many existing chimneys are being capped to keep the birds out. To my mind, many people love seeing wildlife, as long as it isn't on their property. The loss of these magnificent aerialists is deeply regrettable. In watching Swifts fly, we are able to witness what perfection evolution can achieve. What a dreary place the skies over our cities will be when they are no longer sliced by the Swift's feathered sabers.

To learn more about Swifts and what you can do to help protect them, visit at:

1 comment:

  1. Dave I really enjoyed reading the blog! Thank you for taking the time to write about these very special birds. Also thank you for the kind words about my efforts! child like affection? really? Am I that obvious in my delight and love for them? :))))