Hare traffic control: managing to keep wildlife away from planes at Dublin Airport

Dawn breaking over the Irish Sea, you are on an overnight flight approaching Dublin Airport. As you look out the window at the comforting lights of the terminal a few thoughts might be going through your mind.

You might be hoping there aren’t too many queues at passport control, or longing for a coffee or willing the pilots to ease down gently as they land.

Out on the south runway, a large Irish hare doesn’t give one jot about your thoughts, or your pilot’s, as he gallops across or towards your plane at up to 35 miles per hour. He is a lovestruck young male with no thought for safety and only one thing on his mind – pursuit of a prospective mate.

If it is North America, it might be deer, and if it is Botswana it might be giraffe, University College Cork (UCC) researcher Sammy Ball says.

John FitzGerald: An attempt to buy the next election with a giveaway budget would be a gross miscalculation

---

Justine McCarthy: We need to talk about why we’re all so angry

---

Selling out Croke Park proves Leinster have broken the mould in terms of marketing their brand

---

“There was an incident involving a small aircraft and a giraffe, and neither the animal nor the plane came out well,” she adds.

Over the past 25 years, intense agriculture has driven hares to find more conducive habitats. With plenty of long grass for cover and plenty of fencing to protect against dogs, the airport has become a paradise for the Irish hare (Lepus timidus hibernicus), which is a protected species.

Sadly, since 1997, more than 340 hares have been killed by planes at Dublin Airport.

It is a European problem. A long-grass management policy to try to deter birds is a magnet for mammals. While bird strikes are the most common hazard, wildlife strikes are also risk causing serious damage to an aircraft. This can range from cracked or broken windshields to damage to a fuselage or landing gear to engine failure if ingested.

For the past four years, Ball has been working with the Dublin Airport Authority (DAA) on a humane management strategy for their Irish hare population that protects both aircraft and animal.

How did she get involved? “I originally looked at parasites in hare populations during my undergrad research at UCC, and we needed hare carcasses,” Ball explains.

[ Dublin hare-port: the oldest mammal in Ireland is in flying form ]

“Dublin Airport was one of the only places we could get them – well, the only place really – as strike events were increasing there year on year,” she says.

Once that work was completed, the DAA spoke to UCC about undertaking esearch on hares, and the Irish Research Council supported the project financially, she explains.

Dublin Airport records over the past 30 years show there has been an average of at least one hare strike a year. However, there has been a 14 per cent increase, with 1.89 strikes per 10,000 aircraft movements in 2018. From 2019 to early 2023, there were 21 additional hare strikes, she says.

Fortunately, there have been no serious incidents involving aircraft, but the hare never survives. “Hares typically strike the wheels of an aircraft, and there are no records of them being ingested into aircraft engines,” says Ball.

A “strike” is defined as occurring when a carcass is recovered from a runway or an airline reports damage. Part of Ball’s research involved studying the “kinetic energy” of a strike event and the damage potential.

Ball spent her four years working with station manager Colm Naughton, and his colleagues at the Dublin Airport Fire and Rescue to study hare movements with a view to coming up with an ecological strategy.

“We had tried to remove the hares in a humane way – as in relocate them – but due to the joys of nature, they filled up the airfield again fairly quickly,” says Naughton.

“Buck hares are quite large,” he continues. “We did have an instance with a Spanair pilot who called for some assistance and referred to it as a kangaroo-type creature! In March in particular, they only have one thing on their mind. They will come within a few feet of you, and even come through the station.”

Naughton knows all about how well hares can hide, having memories as a 14-year-old of galloping through long grass and ending up flat on his face.

“The hares mat the grass over for their nest, and the leverets sit into it,” he says. “They weave it so well, and it gives great cover to the leverets, but if you are legging it and you don’t watch where you are going ...”

Ball began by trying to gauge the airport’s Irish hare population, using distance sampling and modelling numbers to come up with an estimate of 120 individuals spread across the airfield.

“We deployed a few different methods for this, including remote sensing – as in technology that we can use without having to be physically present. We had motion-activated camera traps, mounted around several places and we would then look at the time stamps recorded on those images,” she says.

Using that information, she modelled activity patterns, as in the Circadian rhythm of hares over a 24-hour period. “We fitted five hares with GPS collars in November 2021 – some of the hares are still wearing them as they can be hard to capture, being so clever.”

Ball found that the peak of hare activity and their strike risk, based on aircraft movements, can be narrowed to two distinct periods – 4am to 7am and 9pm to midnight. March tends to be the busiest month for hares darting on to runways.

She also identified several “hot spots”, including the Irish Coast Guard search and rescue helicopter base, and the area along the threshold of the runway 16/34.

“There is quite a lot of long grass around the helicopter pad, and then runway 16/34 has also been close to construction activity. We had a family group of 10 hares in that area,” she says.

She spent many nights looking through binoculars and downloading data using a million-candle power torch to reflect the eye shine of hares, which allowed her to count them at night.

The information she gathered was invaluable to the DAA. It now knew when best to deploy fire trucks to try to scare the mammals. However, implementing scare tactics is not easy.

A trip out with Ball and Dublin Airport fire and rescue officer John Walsh in one of his station’s trucks reveals how difficult it is.

“We always have one fire truck out, if not two,” says Walsh, explaining how birds are his most frequent challenge.

“Once they are committed to land, pilots don’t have much time to go around to pull their aircraft back up,” he says.

“If you see the starlings, you can take an action and scare them, providing it is safe to do so, in between aircraft. You might have the aircraft traffic control contacting you saying they’ve seen bird activity, or a pilot has landed and will contact the tower,” he explains.

“You get out of the truck with your gun, and you are firing long range cartridges most of the time,” says Walsh, demonstrating how this is done. “They are pyrotechnic, and explode up in the air at a safe distance. When you fire, you get the first bang, and when it goes up in the air it explodes itself.”

Starlings, wood pigeons and gulls tend to be the most frequent species, while racing pigeons do cross during summer. Owners normally give advance information and try to steer the birds clear of runways, he says.

“Occasionally we do get swans. If the runway is very wet, it can mimic a river or stream, so you might get birds landing thinking it is a stream or a river,” Walsh notes.

“For hares, they are more difficult to move as they don’t really listen. If you just drive over near them, that is usually enough to disperse them, using the accelerator on the vehicle,” he continues.

“Mammals can become habituated to noise,” Ball confirms. “It doesn’t seem to bother them at all, and so we found that visual stimulus was the most effective.”

Walsh also has simulated sounds in his van which he can transmit when an aircraft is in the vicinity and it is not safe for him to fire.

The “distress tapes” are so called because they mimic sounds of birds in distress, ranging from starlings to lapwings to the most scary – black-headed gulls.

“The biggest deterrent is being constantly out here, where you are constantly harassing them and trying to keep them on edge,” Walsh says.

As we drive by the south runway, a flock of birds rises from the long grass. Among them are about 20 curlews, another protected species.

[ You want an index for Ireland’s biodiversity crisis? I give you the humble curlew ]

[ Anti-blood sport campaigners criticise finding that hares do not experience greater risk of death after coursing ]

The cleverest animals of all on the airfield are, not surprisingly, foxes. “I could definitely tell you on the fingers of one hand how many times we had a fox strike, in 28 years,” Naughton says. “They know where they should and shouldn’t be. They are amazing survivors and could teach us a lot ... It is the dumb humans who get up at 5 o’clock to sit in traffic on the way to work ...”