The site comprises the grass-covered islands of Hornøya and Reinøya and islets of Prestholmen and Lille Avløysinga (totalling c.150 ha of land) plus c.50 ha of intervening sea. The western part of Hornøya is 65 m high, with steep cliffs facing westward, while the eastern part is flat. Reinøya has no steep cliffs. Hornøya is the easternmost point of Norway at 31°10'E; there is a lighthouse at its northern end. About 10,000-30,000 eggs of Larus argentatus are collected per year. Hornøya is owned by Vardø municipality and the Lighthouse Department, while Prestholmen belongs to the vicar in Vardø.
The islands hold the largest colony of Larus argentatus in Europe, as well as many thousands of pairs of a wide range of other breeding seabirds, e.g. Rissa tridactyla (at least 20,000 pairs). Polysticta stelleri is common from January to April in large, dense flocks (totalling more than 400 birds).
BirdLife International (2020) Important Bird Areas factsheet: Hornøy and Reinøy. Downloaded from http://www.birdlife.org on 07/08/2020.