Gannets flock back to Wales as the seabird season gets underway

Published: 12 March

After spending the winter months in southern European and African waters, Northern Gannets are now returning to their breeding colony on the small, rocky island west of Pembrokeshire. Their arrival marks the beginning of the seabird season along the Welsh coast.

Grassholm is one of the largest Gannet colonies in the world, with thousands of pairs gathering here each year to breed. Not long ago, during the height of the season, the island once appeared almost entirely white from a distance – blanketed by birds standing shoulder to shoulder across the rocks.

Gannets are among the most striking seabirds at sea. With wingspans approaching two metres, they glide effortlessly above the waves in pursuit of fish. These spectacular dives can reach speeds of more than 60 miles per hour as the birds’ spear into shoals of fish beneath the surface.

Despite spending months far out in the Atlantic – with some travelling as far as the coasts of Portugal and West Africa – many Gannets return with remarkable precision to the very same nesting sites each year. Pairs reunite with a distinctive greeting display, stretching their necks skywards and gently tapping their bills in a ritual that helps strengthen their long-term bond.

The sound and movement around the island build quickly as more birds arrive. Gannets begin repairing their nests with seaweed and other materials, while the air fills with the constant flow of birds commuting between the colony and nearby feeding grounds.

For decades Grassholm has been one of the most important places in the world for Northern Gannet. Before 2022, the island supported the third-largest colony, with around 36,000 pairs – nearly 10% of the global population gathering here each year.

But in recent years the colony has faced a major challenge. In 2022, a devastating outbreak of Highly Pathogenic Avian Influenza (HPAI) swept through seabird colonies across the UK and Europe. On Grassholm, the impact was dramatic, with the Gannet population declining by more than 50% in just a few months.

Although the colony has stabilised, recovery has so far been slow. Surveys in 2025 recorded around 17,000 breeding pairs on the island – a stark reminder of how vulnerable even the largest seabird colonies can be.

Yet there are also signs of resilience. Each spring, thousands of Gannets still return faithfully to Grassholm’s cliffs and rocky slopes, rebuilding nests and re-establishing their bustling seabird city. The island is also becoming increasingly important for other species, with Guillemot numbers rising in recent years. In 2025, more than 8,000 were recorded.

Although Grassholm lies several miles offshore and is not accessible to visitors, the return of seabirds like these is a powerful reminder of how important Wales’ offshore islands and rich seas are for wildlife.

As spring unfolds, Grassholm will once again become one of the busiest seabird cities in the North Atlantic.  And each bird that returns is part of a story that is still unfolding. For now, their return offers a strong reminder that Wales’ wild islands and coastal waters remain vital places for seabirds.