Wildlife & Roads
Wildlife Road Fatalities in Ireland: Lessons from Research and Paths Forward
The number of vehicles on Irish roads has jumped from 2,570,294 in 2015 to 3,1000,000 in 2024. A 2017 survey of 9,500 motorists, by the AA, found 13% had been involved in at least one collision with an animal, or bird.
Ireland’s expanding road network has become one of the most pervasive threats to wildlife, bringing vehicles into daily conflict with animals moving through their habitats. While the scale of losses is hard to quantify, the available research, citizen-science reporting, and dedicated ecological studies show that the toll is significant but that solutions exist.
Who is being killed, when, and where
Irish surveys confirm that hedgehogs, badgers, rabbits and foxes are the most frequently recorded mammal road casualties. Mortality peaks in spring (breeding dispersal) and late summer/early autumn (juveniles on the move). Birds of prey, especially low-flying nocturnal hunters, also feature in collision records.
Otters remain a special concern: protected by law, yet often killed at bridges and culverts where road and river corridors overlap. National guidelines highlight road mortality as one of the greatest anthropogenic threats to Irish otter populations.
Citizen science has played a crucial role in mapping this problem. The National Biodiversity Data Centre’s Road Kill Survey hosts thousands of public submissions, helping identify seasonal trends and geographic hotspots, even if true numbers are under-recorded.
Dr Aoibheann Gaughran and the M11 Badger Study
The late Dr Aoibheann Gaughran of Trinity College Dublin transformed how Ireland understands roads and badgers. Her long-term GPS-collar study tracked badger movements before, during, and after the M11/N11 upgrade in Co. Wicklow.
Her findings were clear: when continuous badger-proof fencing was combined with purpose-built underpasses, badger deaths were eliminated and territories remained stable. After construction, GPS-tagged badgers were documented using the underpasses regularly (around 10 crossings per month). In effect, the right engineering removed the conflict entirely.
Beyond this, Dr. Gaughran’s work illuminated unusual “super-ranging” male badgers and showed how roadworks could increase nightly distances travelled without fragmenting populations – critical insights for disease ecology, conservation, and road design.
Barn Owls and the Road Network – Research by John Lusby
While mammals dominate roadkill statistics, Ireland’s barn owl has emerged as a high-profile avian casualty. Research led by John Lusby of BirdWatch Ireland has highlighted how roads exacerbate the pressures on this already vulnerable species.
Barn owls often hunt along roadside verges where prey is abundant, especially in areas with long grass and rough margins. Lusby’s monitoring has shown that road mortality is now one of the lleading causes of death for Irish barn owls, alongside secondary rodenticide poisoning. The impact is amplified by the species’ fragile population: with fewer than 1,000 breeding pairs in Ireland, every collision matters.
Lusby’s research also points to solutions. By adjusting verge management, avoiding attractive tall grass habitats right at the roadside, and strategically placing nest boxes away from high-traffic corridors, we can reduce the risk. His work mirrors Dr. Aoibheann Gaughran’s in demonstrating that practical, evidence-based interventions can dramatically cut wildlife fatalities.
Common Threats and Proven Fixes
The studies of both Gaughran and Lusby converge on a central truth: wildlife road deaths are predictable, preventable, and must be factored into planning and maintenance as standard.
Key measures include:
- Continuous exclusion fencing and underpasses for mammals such as badgers and otters.
- Bridge and culvert design that maintains dry routes along rivers for otters.
- Targeted verge management to reduce foraging attractiveness for barn owls and other birds.
- Hotspot identification and retrofitting, informed by citizen science and ecological monitoring.
- Maintenance of mitigation structures, as broken fencing or blocked underpasses quickly negate their benefits.
Counting What Matters
At present, Ireland still lacks a single, systematic annual dataset on wildlife road fatalities. Citizen science fills some of the gap, but official, structured monitoring is needed – especially for species of high conservation concern such as barn owls, otters, and bats.
The research mentioned above offers a template: combine rigorous science with practical design, and share findings widely. These studies show that targeted measures work. What is needed now is commitment – to scale them up, integrate them into every road project, and treat reductions in roadkill as a measurable outcome of good infrastructure.
