Improving Breeding Success of North Sea Birds Abroad

Many seabird species that depend on the North Sea spend part of their life cycle in Dutch waters but breed elsewhere, particularly in the United Kingdom, Norway and other North Sea countries. As a result, improving breeding success often requires action beyond Dutch waters. This study explored which international measures can contribute to higher breeding success for seabirds and migratory waterbirds that depend on the North Sea, and how Nature Regeneration North Sea (NN) can support these efforts.

Breeding success is influenced by a range of pressures, including predation, disturbance at breeding colonies, reduced food availability, climate change, disease outbreaks and, for some species, offshore wind development. The study reviewed existing international projects, conservation measures and cooperation initiatives to identify opportunities that are both effective and feasible.

The review shows that the most promising measures differ between species, but two approaches stand out. The first is predator management and biosecurity on breeding islands, which has been shown to improve breeding success and support population recovery for several seabird species. The second is seagrass restoration, which can strengthen marine ecosystems and increase the availability of food and habitat for multiple bird species.

The study also highlights the importance of international cooperation. Many organisations, governments, researchers and NGOs are already working on seabird conservation across the North Sea region. Rather than developing standalone projects, NN can add value by supporting, connecting and scaling existing initiatives. Key recommendations are to focus on proven measures, invest in partnerships, target locations where impact is likely to be greatest, and combine implementation with long-term monitoring.

The objective of this project was to provide Nature Regeneration North Sea with an overview of international measures that can improve the breeding success of seabirds and migratory waterbirds that depend on the North Sea. The study reviewed potential measures, relevant organisations and ongoing initiatives, with the aim of identifying practical opportunities for NN to support and strengthen international conservation efforts.

Program: Nature Regeneration North Sea (NN)

11/02/2026-31/06/2026

Project dates

The North Sea

Location

Haskoning & Haskoning UK, Nature Regeneration North Sea

Project lead and partners

Northern gannet - Morus bassanus , Great skua - Stercorarius skua, Common guillemot - Uria aalge, Razorbill - Alca torda, Red knot - Calidris canutus, Bar-tailed godwit - Limosa lapponica, Great Black-backed Gull - Larus marinus, Black-legged kittiwake - Rissa tridactyla, Arctic Skua - Stercorarius parasiticus, Herring gull - Larus argentatus

Target species

Methods

This study was conducted as a desk study and literature review. Existing scientific literature, project reports, policy documents and expert knowledge were reviewed to identify pressures affecting breeding success, potential conservation measures, and relevant international initiatives for seabirds and migratory waterbirds that depend on the North Sea.

 

The assessment focused on seven priority species that breed largely outside the Netherlands but are ecologically connected to the North Sea. For each species, key pressures, potential measures, effectiveness, feasibility and opportunities for implementation were evaluated. In addition, relevant organisations, research programs and ongoing conservation initiatives were identified to explore opportunities for international cooperation and implementation.

Results

This analysis identifies how breeding success of North Sea seabirds can be improved through targeted international measures, and where the Nature Regeneration North Sea (NN) program can add the most value. The study combines insights on ecological pressures, effectiveness of restoration measures, and opportunities for collaboration across the North Sea region.

 

Breeding success is currently limited by a combination of pressures. Predation by invasive mammals such as rats, mink and foxes strongly affects breeding colonies, while disturbance from human activities further reduces reproductive success. In addition, food limitation — particularly the availability of forage fish — plays an important role. Climate change and extreme weather increasingly affect breeding conditions, and disease outbreaks, especially Highly Pathogenic Avian Influenza (HPAI), can have severe impacts. For some species, offshore wind developments may also influence breeding success through changes in habitat use or food availability.

 

The results show that active measures are needed alongside pressure reduction to achieve significant improvements. Two measures stand out as particularly effective. Predator eradication and biosecurity on breeding islands have proven highly successful, especially for guillemot and razorbill colonies, leading to substantial increases in breeding success and colony size in multiple locations in the UK. In addition, seagrass restoration offers a more ecosystem-based approach, enhancing fish biomass, improving food availability and strengthening habitat quality. This measure has the potential to benefit a wide range of bird species, including red knot, bar-tailed godwit, guillemot and razorbill, and is considered more scalable at regional level.

 

Other interventions, such as artificial nesting structures, supplementary feeding and disturbance reduction, can contribute at local scale, but are generally more species-specific or less consistently effective.

 

The analysis highlights that impact can be maximised through international cooperation rather than isolated projects. Partnerships with conservation organisations such as BirdLife International, RSPB, NABU, DOF, SSC and BirdLife Norway can support implementation at key seabird colonies outside the Netherlands, while also strengthening collaboration across North Sea countries and enabling co-funding opportunities. Collaboration with research programs such as OWEC, ECOWind and ECOWINGS can further strengthen the scientific basis for ecosystem-based measures and provide access to data and modelling tools. In addition, alignment with policy initiatives such as the OSPAR Regional Action Plan for Seabirds helps ensure that activities contribute to wider regional conservation goals.

 

A key outcome of the study is a clear direction for the role of NN. The program can add most value by funding and scaling proven measures, acting as a connector between NGOs, researchers, governments and industry, and focusing on a limited number of species and locations where success is most likely. Combining implementation with monitoring is essential to ensure that measures are effective and contribute to long-term ecological recovery.

 

Overall, the results show that improving seabird breeding success requires a combination of targeted interventions at breeding sites and broader ecosystem restoration, supported by strong international collaboration.

Download full report:

Enhancing breeding success of shortlisted North Sea birds breeding outside the Netherlands

Tips & Tricks

  1. There is no single solution.
    Improving breeding success requires both colony-level actions (predator control, biosecurity, disturbance reduction) and ecosystem-level actions (food availability, habitat restoration).  
  2. Predator management is the most immediately actionable measure.
    It has the strongest evidence base and can generate measurable results relatively quickly.  
  3. Food availability remains fundamental.
    Many species ultimately appear food-limited, especially through changes in forage fish availability. However, the exact demographic response to prey recovery is still uncertain.  
  4. Seagrass restoration is attractive because it benefits multiple species and ecosystem functions simultaneously.
    It may improve fish biomass, habitat quality and food resources, but benefits are indirect and often slower to measure.  
  5. International cooperation is essential.
    Most target species breed outside Dutch jurisdiction, so meaningful conservation gains require action in UK, Norwegian, Icelandic and other North Sea colonies.  
  6. Monitoring is critical.
    Many measures look promising, but long-term evidence for population-level benefits is still limited. Every implementation project should therefore include monitoring and adaptive management.  

Let's talk

Would you like to know more about this project or get involved? Send an email to the project lead.

lotte.braat@haskoning.com