Offshore islands are important breeding habitats for the UK and Ireland’s seabird populations but are disproportionately affected by introduced mammalian predators such as rats and mice. Populations of burrow- and crevice- nesting seabirds such as Black Guillemots are especially vulnerable to invasive mammal predation due to the accessibility of their nests. 

Black Guillemots breed on Rathlin Island Special Protection Area (SPA), County Antrim, which hosts Northern Ireland’s most significant seabird assemblage. The Rathlin Acting for Tomorrow (LIFE Raft) partnership project (2021–2026) has been working to eradicate invasive Brown Rats and Ferrets for the benefit of Rathlin Island SPA’s internationally important seabird colonies and to enable wider native species recovery. 

Because disturbance and mortality to seabirds caused by predators is likely to occur when Human observers are absent, they are challenging to detect and monitor. Added to this, the often remote and difficult terrain of seabird colonies increases the challenge of making consistent direct observations. Hence, motion-triggered camera traps, which can be left in the field to passively collect observations of predators, can be useful in monitoring the effectiveness of eradication programmes in seabird colonies. 

To complement the aims of the LIFE Raft project, this study trialled the use of camera traps to assess predator presence in two Black Guillemot colonies to inform the conservation management of this seabird species. Remote cameras were effective in capturing potential conflict species, which may cause mortality or injury to adults or chicks based on previous literature. 

These species were observed on 98% of the total study days, with nine species observed on Lighthouse Island and five on Rathlin. Conflict species including Hooded Crow, Herring Gull, Raven, Magpie, Otter, and Brown Rat were captured investigating Black Guillemot nest sites, predating on Manx Shearwaters, and interacting with Black Guillemots through kleptoparasitism (food theft). 

No predation of Black Guillemot adults, eggs or chicks was observed with camera traps, suggesting that in the focal locations in this pilot, direct predation may not occur frequently enough to be recorded using the methodology deployed here, or may not be observable using the current methodology.