Carbon Dioxide Tolerance of Rabbits and Its Relation to Burrow Fumigation

Abstract

The survival time of wild rabbits exposed to elevated concentrations of carbon dioxide (30–60%) was more than double that of a domestic strain. For example, at 50% CO₂, mean survival time of wild rabbits was 71 minutes and that of domestic rabbits was 23 minutes. For the wild rabbits, constant levels of carbon dioxide greater than 30% are required for lethality. These findings support the pre-existing generalization that fossorial mammals have adapted physiologically to increased carbon dioxide concentrations encountered in their burrows.

Dry ice was used as a source of carbon dioxide to evaluate whether this agent could be used for fumigation of rabbits in their burrows. Carbon dioxide treatment of a natural burrow showed that this is not effective, owing to the high concentration required for lethality and the inadequate distribution of the gas to all regions of the burrow. The factors which determine poor dispersal of carbon dioxide through the burrow suggest limitations to the effectiveness of some other commonly used fumigants for rabbit control.