Low Nest Success of Black-Legged Kittiwakes (Rissa tridactyla) at a Mainland Colony Is Not Associated With Disturbance From Walkers or Boats: Implications for Compensation for Offshore Renewables Impacts.

Seabirds face a range of pressures including rising sea temperatures, declining food availability, offshore renewables and disturbances at their onshore nesting colonies. Developers of marine renewables often seek to implement compensatory measures to offset risk and enhance productivity through targeted management interventions, including reduction in disturbance. To evaluate whether such interventions could be effective at a mainland protected area in Scotland (St Abb's Head), we analysed a dataset of > 1400 kittiwake nests monitored across nine plots over 7 years (2015-19 and 2022-23) to (a) assess potential impacts of increasing numbers of walkers on cliff tops and boats operating close inshore on nest success and number of chicks fledged, and (b) assess whether productivity is sufficient to sustain the local population. We found no strong evidence that people or boat activity negatively affected nest success or number of chicks fledged. Rather, we observed weak positive correlations between human presence and both nest success and the probability of successful nests fledging more than a single chick, which potentially demonstrates a 'human shield' effect reducing predation rates. This suggests that mitigation of disturbance at this colony would not represent a viable compensation measure for kittiwakes. However, productivity (chicks per pair) across the study period was at the lower end of levels previously predicted to sustain kittiwake populations. This raises concerns about the future viability of the population if juvenile or adult survival rates decline due to anthropogenic drivers such as offshore wind development, climate change, or impacts of novel infectious diseases.