The visit to the Tokelau Islands described below is the third carried out in a study of ecology, rat control and related problems. The first visit in 1966/67 (Wodzicki 1968 A) was devoted primarily to the study of the ecology of the Polynesian rat (Rattus exulans) and the environment, including the animals and the vegetation, of Nukunonu atoll. The main objects of the second expedition in April-June 1968 (Wodzicki 1968 B) were the initiation of a long-term investigation of rat damage on all three atolls and the training of two men from each island as rat control operatives.

The Pacific islands of Oceania cover almost 15% of the world’s surface and are characterised by a high degree of ecosystem and species diversity. The region is characterised by thousands of isolated small coral atolls and higher volcanic islands, which has led to the high diversity of species found today. In fact, the number of plants and animals found nowhere else on earth (endemic species) is extremely high - often up to 90% for particular groups. Often, these rare and endemic species are adapted to specialised habitats and limited to small areas of a few islands.

The Tokelau Islands consist of three atolls (Atafu, Nukunonu and Fakaofo) approximately 500 km north of Western Samoa. Their numerous islets are formed mainly of coral sand and rubble with no standing freshwater. Sixty-one plant species have been recorded, 13 of these being introduced and 10 being adventives. There are three vegetation zones, the beach, the beach-crest, and the interior coconut/fern zone with the physiognomy of a humid tropical forest. Marine invertebrates have not been studied.