The Gilberginsel - or colloquially simply Vogelinsel - is located in the Biggesee about 3.5 km from Attendorn. Only a narrow stretch of water separates the island from the shore. The island itself is the only island in the Biggesee and is uninhabited. Together with the adjacent water area, the entire island has been a nature reserve since 1985. The size of the nature reserve is 96 ha. The main reason for the protected status was the settlement of a gray heron colony.
Until 2007, the island was mainly covered with spruce trees, but most of them fell victim to the storm Kyrill. Although many eyrie trees were destroyed by the storm, cormorants began breeding on the island just one year later. Today, gray herons and cormorants share the few eyrie trees near the shore. The largest gray heron colony in the Olpe district breeds here. After their dives the cormorants sit with outstretched wings on branches or stones and let their wings dry. This characteristic posture makes the medium-sized water birds, which are excellent divers, very easy to spot.
Due to its undisturbed location (the island is closed to shipping traffic) and excellent interlocking of forest and aquatic habitats, the island provides excellent resting, breeding and resting habitat for waterfowl. Birds find rest here throughout the year. Overall, Gilberg Island is a nationally significant stepping stone biotope and, together with the Ahauser Stausee, about 6 km away, provides a valuable refuge for waterfowl.
During the winter months, volunteer ornithologists record the waterfowl populations around the Bigge and Listersee lakes. If you would like to report your own observations or see who has made which observations, you can use the Internet portals www.naturgucker.de or www.ornitho.de. A very good possibility to observe the water birds is the bird watching station of the nature park at the Biggesee. The lookout point is located opposite the Gilberg islands and can be reached via the Biggerandweg. Well protected behind small peep windows, the chance is especially great to observe the stars such as cormorant, gray heron, great crested grebe and Co. around the Gilberg Island.
Attention: The Gilberginsel may not be entered! Immediately around the island is also a no-driving zone for boats.