Documenting the longevity of an animal marker hair dye on small mammals

Permanent marks such as ear tagging and passive integrated transponder tags have been successfully used in small-mammal mark–recapture research. However, permanent marks can influence small mammal behavior and promote infection. Hair dyes may be favored for short-term mark–recapture studies because they are low-cost, can be applied easily, and are less damaging to marked individuals. Our objective was to determine the longevity of an animal hair dye marker placed on small mammals. Our study was conducted at the Millersville Biological Preserve in Millersville, PA and consisted of two transect lines, each with 10 Sherman traps checked twice a week over 3 months. We captured 27 individuals and marked each of them once with hair dye. Hair dye longevity was monitored via photodocumentation of recaptured individuals. Results showed that the hair dye can be used to distinguish individuals for up to 60 days in short-term mark–recapture studies of small mammals.