Some factors influencing the outcome of shelter competition in lobsters (Homarus americanus)

Some factors involved in the competition for shelter between lobsters 40–70 mm carapace length were examined in the field and in the laboratory. Dominance, usually indicated by greater carapace length, male sex, hard exo‐skeleton and a numerical or length advantage in claws increased the likelihood of capturing and holding a shelter. Prior residence in the shelter, right or left position of the crusher claw, or absence of both antennae did not influence the outcome of the shelter competition. Sharing of shelter was rare except when both members of the pair were very close in size or one or both lobsters were missing one or both claws. Field observations indicated that laboratory stresses may be responsible for the clear‐cut relationship between dominance and shelter possession. When, in the laboratory, size graded groups were allowed to burrow under a long flat board the total number of lobsters occupying shelters decreased with time and the dominant animal controlled most of the burrow sites.