Long adult life, low reproduction and competition in two sub‐Antarctic carabid beetles

. 1. On the biologically impoverished sub‐Antarctic Ile de la Possession, Iles Crozet, Amblystogenium pacificum Putzeys and A.minimum Luff (Carabidae), both opportunistic carnivores, coexist in fellfield habitat above 120 m altitude, where they hunt prey in inter‐stone spaces. 2. Beetles show marked claw wear showing that many individuals survive to breed in their third or later year of adult life, and in some years, particularly in A.minimum , populations consisted largely of very old beetles. This coupled with evidence from ripe egg numbers, of rarity of tenerals and of larvae, shows that adult recruitment rates were usually very low. 3. In fellfield the coexisting species pair have non‐overlapping size distributions with A.pacificum the larger. In moorland A.pacificum adults occur in isolation and are smaller and overlap the size ranges of both species in fellfield. These facts are interpreted as character displacement or release, reflecting present‐day interspecific competition, probably for food. Supporting evidence was obtained in terms of apparent size‐differential survival of beetles of different ages.