Reducing shrew mortality in Longworth live-traps
During a four year field study period, several improvements were made to the method and mechanism of capturing shrews using Longworth live-traps, in order to reduce mortality after capture. The addition of extra food to the traps reduced mortality of common shrew (Sorex araneus) only slightly, indicating that insufficient food supply in the traps was not the main cause of death after capture. Mortality was largely reduced by checking all not-closed traps at every control round for signs of visits by shrews to the nestbox compartment and, subsequently, refilling these visited traps with food. Reducing the space beneath the treadle in the trap tunnel helped to lower shrew mortality further. The combined adaptations to the standard method and to the trapping mechanism reduced shrew mortality (both common shrew and water shrew, Neomys fodiens) by 83%.