“We understand that this letter may cause you concern,” states the correspondence from Transport Infrastructure Ireland (TII) to Fran Mackey and Jacqui McElhinney. The letter is accompanied by a map indicating exactly how much of their property lies in the way of the preferred route of Dublin’s MetroLink rail scheme.

According to Mackey’s estimate, the couple expect to lose 18 metres off their back garden through a compulsory purchase order.

Fran says his neighbours in Coke Ovens Cottages, four picturesque homes clustered along the Royal Canal towpath, can expect to lose similar amounts of land.

“We were shocked. Everyone was in shock here,” he says. Originally from Finglas, in a previous life Mackey worked as a lighthouse technician along the western seaboard. Following stints in Australia, South Africa and New Jersey, he settled at Coke Ovens Cottages in 1987 after a neighbour told him it was like living in the middle of the country but in the heart of the city. “And I said, ‘Right, that’s it.’ I put an offer in and it was accepted eventually.”

It’s just a complete wildlife haven, from the fox to the badger to the otters outside to all the birds, the finches

A pedestrian in Dublin will see plenty of magpies, pigeons and gulls. They won’t see many bullfinches, long-tailed tits, chaffinches, gold finches or black caps. Not that these are particularly special birds; there simply aren’t many areas of the city where they thrive.

But where you will spot them is within a natural enclave containing about 1.5km of hedgerow that stretches west along the rail tracks beside the Royal Canal near Phibsborough – about 2km from O’Connell Street.

The dense line of hawthorns and blackthorns provides ideal cover for nesting birds. Its flowers attract bees and other pollinators. During the long evenings you can watch pipistrelle bats swooping and feeding on insects; nearby frog ponds teem with life. Mackey and McElhinney fear all of this will be swept away.

Future capacity

MetroLink combines the original Metro North project between Swords and Dublin City, and a southside extension that was to stretch to Sandyford (but will now probably go only as far as Charlemont after residents further south complained about disruption). The project aims to cater for future capacity in the suburbs as well as finally providing a rail link between Dublin Airport and the city.

Glasnevin station will be built on a site occupied by Des Kelly Interiors and the Brian Boru pub – namechecked in James Joyce’s Ulysses. Under TII’s plan, the dense stretch of hedgerow and the gardens of Coke Ovens Cottages to the west will have to make way for the new infrastructure.

Mackey says he is pro-MetroLink but he wants the engineers to cause less environmental damage by making better use of existing railway in the area. In its letter, TII says the preferred route, still subject to change, maximises the long-term benefits of the project.

Mackey and McElhinney’s garden stretches down to the railtracks of the Maynooth line. It is a green tangle of wild and cultivated plants, ash, damson and elder trees. Their neighbours’ gardens are similarly verdant. The residents share eggs from their hens and jam from their berries.

Maybe a portion of the hedgerow has to go but you’d seriously have to ask whether that’s necessary

“We’ve nothing probably exceptional,” says Mackey of the local biodiversity. “But we’ve everything. It’s just a complete wildlife haven, from the fox to the badger to the otters outside to all the birds, the finches, they’re all nesting and they’re all in abundance around here.”

McElhinney shows me a video of two otters swimming in the canal in front of their cottage. Mackey says it’s the first time in about 20 years that he’s seen otters here. “They’re not quite resident but they’re passing through on a regular basis. We see them early in the morning.”

Possible impact

Transport Infrastructure Ireland says it and design engineers the Jacobs-Idom consortium are looking at the possible impact of the works on the area around the Royal Canal. “We expect to have the design significantly progressed by the end of the summer and will then be in a position to provide the details,” a spokeswoman says.

“Our goal is to preserve as much as possible and we’d like to be more definitive, but it’s just too early to say. In the meantime we are also reviewing the submissions received during the recent public consultation process, some of which concerned the proposed works at Glasnevin. This analysis will be completed also this summer and we hope will be published in September.”

Ireland does not have a lot of forest and much of what it does have is planted Sitka spruce – a monoculture that’s effectively useless for biodiversity. Hedgerows therefore play an important role.

“Hedgerows are really significant for the Irish landscape,” says Birdwatch Ireland policy and advocacy officer Oonagh Duggan. “We have such low woodland cover compared to Europe, so our hedgerows have provided that function.”

Duggan has not seen the TII proposals but she says it would be a pity to lose more than a kilometre of hedgerow in Dublin city, where it is rare.

Existing biodiversity

Like Mackey and McElhinney, Duggan stresses the need for better public transport. MetroLink is part of this – and there must be some give when it comes to balancing new infrastructure with existing biodiversity. “Maybe a portion of the hedgerow has to go but you’d seriously have to ask whether that’s necessary and if it is necessary you’d have to ask how that’s going to be compensated,” she says.

Mackey and McElhinney say they have met officials and engineers from MetroLink a few times and the conversations have been good – there is a willingness to work things out. But at the moment the preferred proposal will destroy a lot of vegetation.

The couple hope TII rethinks the plan and comes up with something that provides better protection for the area. Standing beside an elder tree in his backyard, Mackey mentions the bats and the fledgling birds he sees every year. “They’re going to have nowhere to feed because, well, the whole environment is going to be completely destroyed.”