Long distance migration of insects to a subantarctic island
Transoceanic migration of four species of macrolepidoptera to subantarctic Macquarie Island has been detected in 7 out of 33 years during the period 1962–96 and is restricted to spring and autumn. Analyses of synoptic charts during the migration period show that autumn immigrants originated from New Zealand and comprised a single species of noctuid moth,Agrotis ipsilon (Walker). Spring immigrants originated from Australia and comprised two noctuids, Dasypodia selenophora Guenée and Persectania ewingii Westwood and a butterfly, Vanessa kershawi (McCoy). Autumn migrations were associated with depressions in the southern Tasman Sea. Spring migrations were associated with the eastward passage of prefrontal airflows ahead of cold fronts which extended from southern Australia to the west of Macquarie Island. In an analysis of one of these events, winds exceeded 30 ms−1 at 300 m altitude and could have transported migrants from Tasmania to Macquarie Island overnight in less than 10 h. Flight activity was assisted by the presence of a nocturnal temperature inversion that maintained upper air temperatures above 5 °C. The effect of potential global warming on the migration and colonization of Macquarie Island by insects is discussed.
Document Type: Research Article
Affiliations: 1: CSIRO Entomology, GPO Box 1700, Canberra, ACT 2601, Australia 2: formerly of CSIRO, now of Tilembeya Consulting, Tilembeya, RMB 777, Urila Road, via Queanbeyan, NSW 2620, Australia 3: formerly of Australian Antarctic Division, Channel Highway, Kingston, Tasmania 4050, now at Department of Geography and Planning, University of New England, Armidale, NSW 2351, Australia
Publication date: November 1, 1999