Studies on the ectoparasites of seals and penguins. III. The distribution of the tick Ixodes uriae White and the flea Parapsyllus magellanicus heardi de Meillon on Macquarie Island

Abstract

On Macquarie I. it rains daily and abundantly; whether the habitat is flooded or not determines whether the tick Ixodes uriae and the flea Pavapsyllus magellanicus heardi can survive and breed. The principal hosts of these ectoparasites are penguins; the degree of infestation of the four species of penguins that breed on Macquarie I. differs because of differences in their breeding and moulting behaviour. Royal penguins, Eudyptes chrysolophus schlegeli, form large colonies which are surrounded by tussock, Poa foliosa. Rock stacks covered with vegetation may be within the colony. The drier conditions within the tussock and on the rock stacks are necessary for oviposition and egg development of I. uriae although larvae, nymphs, and adults can survive submersion in water for many weeks. Royal penguins are present in the colony from September to April, and consequently a blood meal is readily available close to the breeding area of the tick for half of the year. In these circumstances the life cycle of I. uriae can be completed within 2 yr. The other penguin species do not afford such favourable opportunities for population growth of I. uriae. Only the rockhopper penguin, Eudyptes chrysocome, nests in sheltered situations such as caves, or under overhanging rocks. In these drier nests the larval and adult flea, P. magellanicus heardi, can survive, and the larvae can overwinter.