BY BERT BURNETT

The Rathlin Island rat eradication project is a large-scale conservation initiative intended to protect the island’s vulnerable seabird populations by removing invasive rat species. Despite the promising goals, the project has stirred significant environmental concerns. While much of the debate has focused on the issue of cattle potentially accessing poison-laden bait stations, a growing worry surrounds the possible unintended consequences of secondary poisoning on birds and other wildlife.

Rathlin Island, located off the northern coast of Northern Ireland, is a vital habitat for seabirds, including puffins, guillemots, razorbills, and kittiwakes. Unfortunately, the introduction of rats to the island disrupted this delicate ecosystem, as the rodents prey on eggs and fledgling birds. By reducing bird populations, these invasive species threaten the biodiversity and ecological balance of Rathlin. Thus, the eradication project aims to create a safer, more sustainable environment for these birds to thrive.

The routine poisoning carried out round homes and farms etc. is minute when compared to the project being carried out on Rathlin, this is not just a few acres involved, this is thousands of acres with baiting stations at intervals across the whole island.

The project relies on poison bait stations strategically placed across the island. These bait stations are designed to attract the feeding rats without affecting other animals. However, in practice, eliminating invasive rats through poisons in open natural spaces presents serious risks of secondary poisoning.

Secondary poisoning occurs when an animal that has ingested poison is consumed by a predator or scavenger, causing the toxin to enter the food chain. Unlike in urban or farm areas, where animals dying from poison can often be located and removed, Rathlin’s open landscape makes it nearly impossible to collect all poisoned rat carcasses.

Critics are particularly concerned about the lack of focus on how to mitigate the impact of poisoned carcasses on Rathlin’s wildlife. Birds, especially scavengers and predatory species, are at high risk of consuming rats that died from the poison. Large gulls, for example, swallow their prey whole, while birds of prey like owls, kestrels and even sea eagles could ingest enough poison to die themselves or suffer long-term health issues. Smaller animals, like mice and shrews, which are prey for owls and other predators, may also consume poisoned rats and enter the food chain, further exacerbating the risk.

To date, there are few solutions in place to prevent secondary poisoning on Rathlin. Poisoning protocols on the mainland of Northern Ireland require training, and handlers are generally confined to urban or controlled areas where carcass retrieval is feasible. But Rathlin’s wide-open spaces make carcass collection unmanageable, and the sheer volume of rats—potentially thousands—poses a massive risk if even a fraction of those bodies are left out for wildlife to scavenge.

This lack of a retrieval system on Rathlin is concerning, particularly as some poisons can remain lethal in an animal’s body for days after ingestion.

While those implementing the project argue that bait stations are well-designed and carefully positioned to minimise risk, the reality of thousands of poisoned rats across a largely uncontrolled environment leaves a significant gap in this strategy. Without more stringent cleanup and tracking measures, a tragic increase in bird and other wildlife mortality could follow the initiative’s completion.

Birds of prey, such as owls, kestrels, and buzzards, play an essential role in the local ecosystem by controlling smaller mammal populations. These species are highly susceptible to secondary poisoning, as they commonly prey on small mammals and carrion. If these birds consume even a small amount of poison, it can lead to severe illness or death, with devastating effects on their populations.

On Rathlin Island, the poisoned carcasses of rats and other small mammals present an abundant, dangerous food source for these birds. Unlike cows, which may inadvertently access bait stations, birds of prey face a unique risk because of their natural feeding behaviours and reliance on the island’s rodent population as a primary food source.

The British mainland has witnessed similar issues with secondary poisoning among raptors and other wildlife. Due to this, authorities require training for anyone using poisons, underscoring the hazards associated with toxic baits. Despite these protocols, secondary poisoning incidents continue to affect raptors and other birds of prey, even in more controlled environments than Rathlin.

In more built-up or agricultural areas, authorities can monitor poisoned animals more closely, and cleanup procedures help reduce the number of carcasses that remain in the environment. However, the situation on Rathlin Island is far more challenging, as poisoned rats may die in remote locations, making recovery impractical. This uncontrolled exposure to poisoned carcasses could have severe and lasting consequences on Rathlin’s wildlife, even threatening populations that the project aims to protect.

While the Rathlin Island rat eradication project has a noble goal—to restore the island’s seabird populations—it raises important ethical and ecological questions about conservation practices. Secondary poisoning remains an ongoing concern, especially given the island’s wide-open spaces and the volume of rats expected to die over the project’s duration. Without effective carcass retrieval or alternative rat control measures, Rathlin’s birds of prey and other scavengers may face an unintended and potentially deadly consequence.

In moving forward, conservationists may need to explore alternative methods that reduce the risk of secondary poisoning. Balancing the protection of seabirds with safeguarding the broader ecosystem will be critical to ensuring that Rathlin Island remains a safe and vibrant haven for its diverse wildlife.

Bert Burnett is a retired gamekeeper of more than fifty years experience.