A technique for rapidly quantifying mammal hair morphology for zoological research

Abstract

Within the zoological disciplines the study of mammalian hair has mostly been limited to crossspecies comparisons, but there is also considerable intraspecifi c variation in hair characteristics that may be biologically meaningful and deserving of study, though it can be tedious to manually measure hundreds of hairs under a microscope. Here a method is presented for assessing a variety of morphological characteristics of mammalian hairs that is fast, nearly fully-automated,does not require a microscope, and that could easily be used by wildlife biologists or researchers studying museum skins. Using hair samples from 6 captive white-tailed deer (Odocoileus virginianus) hairs were placed in groups of ten on white 3×5 inch index cards and covered with clear packing tape. Cards were scanned with a standard fl atbed scanner at high resolution (1200dpi) and the images imported into a computer image analysis program. The program automatically selected and measured each hair, relayed the data to a text fi le, and cycled through all images so that the 120 deer hairs examined (20 per animal) were all measured within 5 minutes. The data returned included the length of each hair (even if it was curly), the width (the average width of the entire shaft), the 2-dimensional surface area, as wellas the colour of the hair, measured with hue and brightness scores averaged over the entire shaft. These data are well-suited for examining questions regarding factors infl uencing the morphology or colour of mammalian pelage, or for using hair morphology to assess the nutritional status of individuals, as is done with humans. When measurements are completed, cards can be conveniently stored, either in an indexcard box or ringed binder, and they can even be re-scanned (at higherresolutions, for example) if needed. Alternatively, the index card step could be skipped and hairs could be scanned loosely in batches. Either way, this method should allow zoological researchers to pursue awide variety of questions relating to mammalian hair morphology.