Action: Alter habitat to encourage birds to leave an area
A single before-and-after study in the USA found that an entire Caspian tern Sterna caspia population moved following (amongst other interventions) the alteration of nesting habitat at the old colony site.
Many ground-nesting seabirds require little or no vegetation to be able to nest. Therefore, if conservationists are trying to move a colony, for a number of reasons, they can make the habitat at the old site unsuitable by encouraging vegetation to grow there.
Many species of seabird disperse from colonies outside the breeding season, allowing work to be carried out without disturbing birds.
Supporting evidence from individual studies
A before-and-after study on two small islands in the Columbia River Estuary, Oregon, USA (Roby et al. 2002), found that an entire Caspian tern Sterna caspia colony (approximately 8,900 pairs) relocated from Rice Island to East Sand Island between 1999 and 2001, following habitat alteration on Rice Island. Wheat Triticum aestivum was planted and silt fencing erected to encourage vegetation growth, whilst suitable habitat was prepared on East Sand Island (see ‘Habitat creation – intertidal habitats’) along with several other interventions (see ‘Use decoys to attract birds to new nesting areas’, ‘Use vocalisations to attract birds to new nesting areas’ and ‘Control avian predators on islands’). The impact on conflict reduction (the purpose of the translocation) is discussed in ‘Move fish-eating birds to reduce conflict with fishermen’.