Stranger Swifts: Conserving One Of The World’s Fastest Birds In Dublin City

What involves cycling like a maniac around the city at odd hours of the day, juggling notebooks and cameras, and chasing down your quarry by the sound of it screaming overhead? Surprisingly not the latest plotline of Stranger Things.

I was employed for three months this summer as a Swift Fieldworker with Birdwatch Ireland, Ireland’s largest conservation organisation. Our goal was to track down as many swift nests as possible, record them, and produce a report for Dublin City Council, who requested the survey as part of their Biodiversity Action Plan.

What is a Swift?

The common swift (Apus apus) is only about 15 centimetres long, and while they might look more like a house sparrow, they’re actually close relatives of the hummingbird. They’re migratory birds,, spending their winters in Africa and travelling to Europe and Asia to breed in summer, generally arriving from the start of May and leaving in early August.

Swifts possess long sickle-shaped wings, and recessed eyes which reduce drag, making them perfectly designed for a life on the wing, with birds only touching land when they breed. Some birds are estimated to spend between ten months and three years completely airborne! Their scientific name means “without feet”, and that’s pretty accurate, given that they are barely able to walk, and can’t perch like many birds, only clinging to walls and other surfaces where they build their nests.

Historically, swifts nested in gaps in trees, cliffs, and other rocky outcrops, but have become an adaptable urban species. The majority of swifts in Europe these days nest in our homes, making use of holes under gutters, old vents, and gaps in brickwork. Unlike the nests of similar-looking birds like swallows or martens, the nest of the swift is inside the chosen structure, not visible from the outside. This plus their tendency to travel huge distances every day to feed makes them an extremely challenging species to monitor!

The reason I spent so many mornings riding around Dublin looking for these flying crossbows is that over the last twenty years swift populations have declined by 60%. This is mainly due to building methods that are hostile to them, as well as issues such as climate change which impacts on their food source and how often they can get out to find it. In Ireland, they are now on the Red List of endangered species, along with species such as the curlew, puffin, and kestrel. This makes it extra important to know how many swifts are nesting in major urban centres, and where they’re successfully reproducing.

Thinking Like a Swift

As the saying goes, to find where a swift is nesting you have to think like a swift. Swifts socialise around their nest sites in the mornings and evenings, swirling in calling groups called “screaming parties”. These are composed of mated pairs (they pair for life) and younger birds who are learning about good places to build their own nests. We call these “bangers” as they often “bang” at suitable spots to check if anyone is home.

You’d think that amassing in large flocks like this would make it easy to find their nests, but other aspects of their lives ruin any potential simplicity. Swifts return to their nests relatively infrequently, often only once every forty-five minutes, earning them judgemental looks from clingier bird species. Their eggs and chicks are tolerant of changing temperatures, chicks entering a torpor-like state when conditions are bad. Swifts, as the name suggests, do everything at speed, with an average cruising speed of 40kph and a top speed of over 100kph. Look away for a second, and you could miss the moment an adult enters or leaves the nest, with no guarantee you’ll be able to record it again.

All of this, combined with the fact that there were only two of us surveying the whole of Dublin City, made this an extremely daunting task. Thankfully, we had a network of swift champions who passed on their sightings and joined us on the ground during our morning or evening watches. Without them there would have been a lot more aimless cycling, hoping to hear or see some screaming swifts. The one benefit is that swifts are extremely picky about the weather conditions they venture out in. The insects they feed on are only active when it’s warm and dry, so any day it was cold, wet and windy meant no surveying for us. You don’t often get fieldwork that’s so comfortable!

After two and half months, almost a thousand kilometres cycled, trips on every single public transport option Dublin had to offer, many evenings waiting for swifts to get bored of socialising and enter their nests, and multiple trips to the bike repair shop, my colleague Luke Lambert and I had a grand total of over a hundred nests spread across the city. Without a doubt there were many that we missed, and a final average of one hundred was one we were pretty happy with.

How Are Things Looking For The City’s Crescent Critters?

Our observations confirmed why doing this survey in the first place was necessary. We spoke to many locals who told us of swift colonies that used to exist before their nests were destroyed by renovations and modern building methods, where any holes and gaps a swift might have used are sealed up. Members of the public told us of having noticed that the number of swifts that return each summer is declining every year. Once I watched a pair check every house on a street for their nest, flying in distressed circles when they found the entrance blocked.

Prime swift real estate (Image Credit: Danielle Crowley, CC BY 2.0)

Luckily, compared to many other species, swift conservation is easy. Nest boxes and “swift bricks” are available that they will use, along with caller systems to attract them. As they are site faithful and social, establishing a colony is relatively easy. Building renovations can be adapted for swifts, like these ones in Trinity College Dublin. Many homeowners are unaware they have swifts living with them, as they are only present during the summer months and are not as messy as many other urban species. The only problem are renovations taking place that harm swifts if the owners are unaware of them.

Ireland is not in a good place biodiversity wise. But swifts could be a gateway species to get people to sit up and pay attention. Most people we spoke to during the survey either were already happy to see the swifts or delighted to learn more about them. Nearly everyone said they were aware of the climate crisis and wanted action on it. Maintaining habitat for swifts and their prey (via pollinator friendly areas) is extremely easy to do with a little knowledge and can engage communities. Making other environmental changes, such as reducing city car use, not only reduces emissions but keeps people and swifts healthier (as well as future fieldworkers who don’t want to be terrorised by motorists).

I really grew to love swifts during my time monitoring them, now going into winter I look forward to hearing that high pitched cry during summer evenings, and I don’t think it’s a big ask for us to maintain that for future generations.

If you want to learn more about providing homes for your local swifts, you can download the Birdwatch Ireland Saving Swifts Guide, which has all the information you need about nest boxes here. You can also listen to podcast episode on swifts from Birdwatch Ireland’s In Your Nature podcast here.


Danielle Crowley is an ecologist and science communicator currently working with BirdWatch Ireland’s Swift monitoring program. She has just started a Marine Vertebrate Ecology and Conservation MSc with the University of Exeter, and co-hosts the fish-based podcast Movie aFISHianados, which you can listen to at this link. Follow Dani on Twitter @Aqua_Dan1.

Image Credit: Marc Pascual, Pixabay licence

Leave a Reply

Fill in your details below or click an icon to log in:

WordPress.com Logo

You are commenting using your WordPress.com account. Log Out /  Change )

Google photo

You are commenting using your Google account. Log Out /  Change )

Twitter picture

You are commenting using your Twitter account. Log Out /  Change )

Facebook photo

You are commenting using your Facebook account. Log Out /  Change )

Connecting to %s