A number of species of reptile ticks in Australia, particularly those using the sleepy lizard (Trachydosaurus rugosus) as their dominant host, form parapatric boundaries wherever they come into contact. A variety of hypotheses have been put forward to explain these boundaries, none of which has yet been demonstrated to be correct. Two of these, one involving reproductive interference and the other competition for attachment sites to hosts, were based on field observations of differences in attachment sites between species and regional variation in attachment sites within species. These hypotheses assume that species-specific attachment site preferences are static. Here we show, using data from single-species infestations of T. rugosus, that this is not the case for either Aponomma hydrosauri males or Amblyomma albolimbatum males or females. We suggest that dynamics in attachment site choice are driven, at least in part, by male movement in search of females.