Lambert’s Bay Bird Island’s Cape Gannet colony reaches record numbers

With daily monitoring and innovative management, Lambert’s Bay Bird Island is Southern Africa's most successfully conserved Cape Gannet colony.

Bird Island in Lambert’s Bay has become a shining example of conservation success. The island is home to one of the most thriving seabird populations in the region and thanks to daily monitoring, patrols, excellent management techniques, and a commitment to conserving the delicate ecosystem, Bird Island has seen record-breaking Cape Gannet numbers and a steady rise in the health and stability of the colony. This is also indicative of ocean health in the vicinity of the island and Bird Island is the only Gannet colony in the world you can walk to.

During January 2025, the Cape Gannet population reached an impressive 45,000 individuals—its highest in 19 years! This marked a significant milestone for the island, with numbers consistently remaining in the 30,000s over the past five years. The significant growth of the colony is not just a product of local breeding success on the island, but it suggests that Gannets from other colonies are flocking to Bird Island, recognising it as a prime breeding ground. Gannets have a protracted breeding season with the earliest eggs laid in October and the last chicks hatching right into May the following year.

Bird Island offers the perfect conditions for the birds to thrive, with enough space, minimal predation, access to food, and consistent conservation efforts, making it ideal for Gannets seeking a safe home to raise their young.

The dedicated team based at the nature reserve has contributed immensely to the incredible population growth at the island. Unlike other colonies, Bird Island’s Cape Gannet population is observed every single day by a conservator and three monitors. The team conducts thorough patrols around the perimeter of the colony, observing for any signs of disturbance or threats to the colony’s health. This includes monitoring for mortalities, disease, egg predation by Kelp Gulls, and watching for activity from land-based predators such as mongooses, all of which could pose a threat to adult Gannets, their chicks or their eggs.

The team also keeps an eye on potential illegal human activity, ensuring the island remains safe and undisturbed. Additionally, they track the effects of weather events such as heavy rain, strong swells, and heatwaves, which can disrupt the ecosystem. Threats are mitigated where possible.

A particularly important time in the Gannet life cycle is during chick fledging season, when the young Gannets take their first solo flight away from the colony and out into the open ocean. Every chick is counted during this period, including those that are unfortunately predated on by Cape-fur seals. The team has been gathering this data for the past 18 years, providing invaluable long-term insight into the Gannet colony’s health, growth, and challenges. This data is essential not just for understanding population dynamics but also for adapting conservation strategies to the changing needs of the colony.

The success of the Bird Island Gannet colony can also be attributed to the careful management of the local seal population, which could otherwise pose a serious threat to the Gannets, particularly during chick fledging season. Seals can predate on young Gannets, and without proper control, seals could colonise the island and overwhelm the breeding Gannets, resulting in temporary or permanent abandonment of the site by the Gannets. To prevent this, an invisible barrier line is in place, restricting the seals to a specific area on the western side of the island. If they cross this boundary, they are herded back to their designated zone. This method has proven highly effective in preventing them from encroaching on the Gannets’ space.

During December 2005, on-land seal predation of the Gannets resulted in the entire colony abandoning the island. Fortunately, careful management by CapeNature at the time resulted in a positive outcome. Mitigation measures were put in place to manage the predators and bird decoys had to be used to lure the nervous birds back to land to rebuild what had been lost.

The success of the operations on Bird Island shows what can be done for other wildlife conservation efforts and what can be achieved through sustained dedication and management techniques. With the colony now thriving, Bird Island stands as an example for the future of Gannet conservation and the broader health of Southern Africa’s coastal ecosystems.