Seabirds are the world’s most threatened group of birds, and have globally declined by a conservative estimate of 70% over recent decades. There are many factors driving seabird declines, including overfishing, by-catch, pollution, disease and predation by non-native invasive species. The negative effects of climate change, however, are amongst the anthropogenic threats likely to have the largest impact across seabird populations. 

To assess how seabird populations in the Interreg VA/MarPAMM region may be affected by future predicted climate change, we updated the model used by Davies et al. (2023). In Davies et al. (2023), an INLA-based hurdle model was used to quantify both the predicted change in presence and abundance of seabird species in Britain and Ireland by 2050 in response to an array of climatic and oceanographic variables. National census data of seabirds from the Seabird Colony Register and Seabird 2000 were included in this previous study. 

Here, we update this previous analysis to incorporate updated oceanographic data, and the most recent national census of seabirds in Britain and Ireland, Seabirds Count. We present results for the Interreg VA/MarPAMM region for 16 breeding seabird species for which there were sufficient data, out of a possible 22. 

We predict that 13 species breeding in the study region will decline in their presence probability and abundance by 2050, ranging from -3.4% (Common Gull) to -82% (Razorbill) for presence probability, and from -12.9% (Razorbill) to -62.3% (Atlantic Puffin) for abundance. Although the median predicted abundance change was negative for most species, uncertainty was very high: credible intervals for future abundance included current abundance for all species. Temperature-related environmental variables were the strongest apparent drivers of these declines. The results of these updated analyses broadly aligned with those identified in Davies et al. (2023), though the generally shallower predicted changes likely reflected the shorter time period over which predictions were made (c. 29 vs 50 years). 

There were several seabird species known to breed in Northern Ireland and the wider Interreg VA/MarPAMM region for which it was not possible to run models, generally due to insufficient data on these populations being available, or because there were too few colonies extant. In addition, limitations inherent to: 

1. modelling data with high levels of fine-scale spatial variation,
2. attempting to adequately represent the environmental conditions experienced by seabirds, and
3. the nature of the ecological processes through which environmental conditions influence seabird presence and abundance, may have limited ability of the models to identify fitted relationships. 

Incorporating additional timesteps of oceanographic and seabird census data also resulted in poorer model performance and greater uncertainty, which could be the focus of future work.

Overall, the population of seabirds in the Interreg VA/MarPAMM region is predicted to decline in presence and abundance by 2050 under climate change.