Sundsvollsundet Nature Reserve grabs attention for its heavily populated seabird cliffs. The Reserve is named after Sundsvollsundet which is the narrow strait of water that separates Helløya Island from Bjarkøya island. Helløya includes the uninhabited nature reserve while Bjarkøya is much larger and houses a town.
The Nature Reserve was established in 2004 primarily to protect nesting seabirds but also other flora and fauna. The horizontal ledges of the cliffs in the Nature Reserve are suitable for the star of the island —the Crutch. This word has several meanings, but in Norway it refers to the Black-legged Kittiwake. These seabirds are related to gulls but have different habits. Unlike gulls they are pelagic, meaning they travel great distances out to sea. They seek small fish and shrimps to scoop from the surface. Most gulls nest on the ground or separated from other nests. Kittiwakes nest close together in colonies on cliffs. Listen for the calls of the birds. They are saying “kittiwake kittiwake” in English, or "kitti-væææ kitti-væææ" in Norwegian. Other seabirds inhabit Sundsvollsundet. Black Guillemots stand with upright bodies on ledges while attending nests or resting between fishing trips. Herring Gulls are well known to many as they have adapted to human habitation and food, but it is natural places like this that is their true home. European Shags make messy nests on ledges covered in their own droppings. When near seabird colonies lookout for white falling messages from the birds.