The fate of Mus domesticus demes after destruction of their habitats

To test our hypothesis that gene flow has the potential to prevent genetic isolation of crib populations separated by several kilometres, we caught and marked 137 house mice leaving six cribs being emptied of corn. In an attempt to recapture the mice, we set traps just after crib emptying and again, where feasible, 1–2 months later, in areas surrounding cribs (trap-nights/trap-area in hectares:cultivated fields, 3834/29.4; non-cultivated areas, 2238/4). Additional trapping was carried out near nine empty cribs and in eight cultivated fields (3304 trap-nights, 17.7 ha trap-area), each more than 120 m from cribs. After the six cribs were emptied, we recaptured 11% of the crib mice (distance from the crib:mean 81 m, range 0–570 m). In refuge habitats, away from cribs, a breeding population existed and three crib females bred there after emptying of cribs. In demonstrating long dispersal distances and breeding populations away from cribs, our data support the hypothesis that gene flow is potentially large enough to prevent genetic isolation of crib populations separated by expanses of cultivated and uncultivated terrain. The influence of decreased recruitment on gene migration is unclear. Potential predators on nestlings, such as Norway rats, deermice, shrews and voles, escaped from and were trapped outside cribs.