How we can help declining Swifts — the birds who sleep in the sky
Swift Piotr Picture: Szczypa Flight Swiftconservation / Ie In
Each evening now the swifts screech overhead, their piercing calls part of the soundtrack of summer. These birds are so charismatic that they set the character of midsummer in many places, both town and country. At times they fly high, soaring in big loops, in and out of sight as they meander around tall trees, big buildings, or church steeples in the distance. Then they return and swoop low, speeding past buildings and trees at close quarters, agile and expert. The swoosh of their passing near overhead is a wondrous experience.
Swifts the fastest birds around, their little bodies compact and streamlined. Their sickle-shaped wings are long and narrow, superbly adapted for fast flight. In evolutionary terms, Swifts probably separated from all other birds around 65 million years ago. Having had tens of millions of years to adapt to their fast flying lifestyle, Swifts are able to achieve top speeds of 111 kilometres per hour. This makes these special summer residents the fastest of all birds. Only the peregrine is faster — and only in a steep downward dive. Swifts hold the record for the fastest proven fliers in level flight. Scientists even suspect they are capable of flight speeds of 160 kilometres per hour, though no-one has managed to record or verify this speed as yet.
In order to maintain such athletic abilities, swifts eat a lot of protein, exclusively from flying insects. Unsurprisingly, they are supremely skillful at aerial predation, precise in their manoeuvres as they scoop up tiny flying insects on the wing. Each tiny midge, flying ant, mosquito, spiderling, or hoverfly is snatched out of the sky at speeds of up to 40kmph.
Each long summer day, an adult swift can catch a whopping 25 grams of insects, or approximately 20,000 insects. And at this time of year, tucked away in the crevices of old stone walls and nooks behind red brick buildings they are actively feeding nests full of tiny ones, delicate, stubby-feathered, and hungry. Parents respond to the pleading gape of their nestlings' wide yellow beaks by bringing balls of insect food — the swift version of protein balls. Each pellet of swift baby food contains between 500 and 1,000 individual insects.
Chicks spend a month or so in the nest, depending on the weather and thus the abundance availability of insect food. As they grow bigger and become more agile, they start doing little press-ups on their wings in the nest, an exercise now often filmed with web-cams mounted in swift nest boxes. It was initially thought that the press-ups were for building strength, but scientists now believe that the press-ups are how baby swifts evaluate their weight, assessing if their wings are strong enough to carry them or if they need to lose weight before taking to the air.
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Now, just as we go through the peak of summer, swift nests everywhere are full of juvenile swifts doing press-ups, readying themselves for their first flight. Once they leave the nest these youngsters will not touch down again for three whole years, spending 365 days a year entirely airborne, for three whole years. They sleep as they fly, navigating all the way to Africa and back, several times over, without landing once.
Only when swifts have reached sexual maturity themselves will they return to the nesting colony where egg laying and tending to young requires them to land. In their natural habitat, Swifts would nest in tree holes and natural rock cavities, but these clever birds adapted long ago to human habitats, finding a niche for themselves among buildings of brick and stone. Now they nest in old warehouses, red bricked Victorian library buildings, courthouses, church steeples, and even in cavities under the eaves of regular urban homes.
Despite their speed, agility, and adaptability, populations of swifts have been in decline in recent years. Because swifts are faithful to their nest sites, returning to the same communal nesting locations every year for the rest of their lives, loss of nesting sites has a significant impact on their breeding success. Decline in abundance of flying insects arising from habitat degradation is also impacting swifts, as loss of wetlands continues, dairying intensifies, and our landscapes are made increasingly inhospitable to insect life. In Ireland, the decline in swift numbers has been severe: in the past 15 years, swift populations have dropped by an alarming 40%. This has resulted in the swifts being ‘red listed’ on the birds of conservation concern in Ireland.
In response, conservation actions across the country are helping to provide nesting sites for swifts, facilitating new colonies to establish or existing colonies to expand. The museum building in Trinity College Dublin was a long-established home to a thriving colony, each summer the swifts defining the soundscape of the college campus in the heart of Dublin. But renovations inadvertently evicted the swifts, who upon their return from Africa one May, found their homes demolished. A project to reinstate them around the eaves of the building has fortunately helped swifts to return to the building since 2021.
Swift nest boxes and permanent ‘swift bricks’ installed into old buildings, renovations or new builds offer Swifts much-needed permanent homes. Several new libraries and arts centres across the country have swift blocks built into their fabric, and new extensions to old buildings too can strengthen local colonies. Many school projects have had huge success in providing for swifts too.
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It is time now for each of us to step up for Swifts, before it’s too late. Architects and builders can encourage clients to make provisions for Swifts in their buildings. Large-scale projects, from college campus redevelopments to municipal libraries and school buildings are all ideal places to provide for swifts, both with nesting bricks and in the landscaping of surrounding grounds. Businesses can take action to help swifts too, championing conservation actions as ambassadors for swifts. Community groups can organise events to raise awareness and promote swift conservation projects in their community too.
More information about correct siting and installation of Swift nest boxes or nesting bricks is available from swiftconservation.ie, where there is also comprehensive guidance for architects and builders.
An informative and practical new booklet from BirdWatch Ireland is available to download here
We must all take action to ensure that Irish skies will never be bereft of Swifts, Gabhlán Gaoithe — the 'one who goes with the wind'.