Barnacle Geese first colonised the Russian arctic island of Kolguev in the early 1980s, since when their numbers have steadily grown. Initial colonies were founded on fox-free coastal sand spits, but by the mid-1990s large colonies (> 5,000 breeding pairs) had become established in the Peschanka River delta, reaching 45,000 breeding pairs by the mid-2000s. Subsequently, numerous new smaller colonies (mean ± s.d. = 12 ± 6 nesting pairs, range = 1 –54, n = 18 colonies) started to increase in numbers in the central part of the island, initially associated with c. 30% of all known Peregrine Falcon Falco peregrinus nests in the study area. The overall population size and number of inland colonies continued to grow, and by 2011–2012 all 24 known Peregrine Falcon nests had Barnacle Goose colonies (mean colony size = 54 ± 40 pairs, range = 1–133, n = 13 colonies). White-fronted Geese Anser albifrons and Tundra Bean Geese Anser fabalis rossicus formerly recorded nesting in dense colonies around Peregrine Falcon nests