Scottish seabird conservation action plan: vulnerability report

Main Seabird Pressures and Threats

Climate Change

Climate change is a major driver of global biodiversity loss (IPBES, 2019) and poses a significant threat to seabirds. While there has been considerable research on its impacts, the effects are complex, often indirect, and operate at the ecosystem level, making them hard to separate from other pressures (Burton et al. 2023, Johnston et al. 2021, Mitchell et al. 2020).

Indirect Impacts:

Climate change impacts seabirds primarily through changes in the distribution, abundance and availability of fish prey (Daunt and Mitchell, 2013; Johnston et al., 2013; Pearce-Higgins, 2021). Rising sea temperatures reduce phytoplankton, affecting the food chain and seabirds (Heath et al., 2012), while warming has altered sandeel distribution (OSPAR, 2017a) and may shift fish species like sprat northward (Kjesbu et al., 2022).

Warming seas have been linked to lower breeding success in species such as kittiwakes and guillemots, with effects varying by species and location due to food chain dynamics and different foraging strategies (Burton et al., 2023). Additionally, changes in the timing of peak prey availability and high energy demands of seabirds due to rising temperatures may disrupt their synchronisation and lead to ‘trophic mismatches’ (Keogan et al., 2021, 2018). Ocean acidification and toxic algal blooms, predicted to increase with climate change, also pose threats to seabirds (Casero et al., 2022).

Direct Impacts:

Climate change can directly impact seabirds through exposure to extreme weather conditions. Severe weather can disrupt foraging, lead to poor body condition, and cause mass mortality events (e.g., Fullick et al., 2022; Morley et al., 2016). High winds increase energy expenditure during flight and foraging (Daunt et al., 2006; Frederiksen et al., 2008). Heavy rainfall and flooding during nesting can chill eggs, kill nestlings, and cause breeding failures (Aebischer, 1993). Rising sea levels threaten breeding sites for shore-nesting species like terns (Ivajnšič et al., 2017). Seabirds are also vulnerable to extreme heat, which can affect both them and their food sources (Choy et al., 2021; Piatt et al., 2020). These global impacts compound local threats, reducing species' ability to adapt (MCCIP 2020).