# Sections Aid in Identifying Hair

> Can a single hair in a carnivore’s dropping tell you what it ate? In this short 1939 note, Ned Dearborn shows that the guard hairs of shrews, mice, voles, bats, rabbits and other small mammals can often be identified by the shape of their cross section, and, when that fails, by the pattern of their central core. He suggests building a set of reference drawings and comparing unknown hairs against them under the microscope.

Summary by Kersey Lawrence, Original Wisdom. Updated 9 November 2026. Page: https://www.originalwisdom.com/tracking-literature/1939-dearborn-sections-aid-identifying-hair/

## Citation and access

- **Authors:** Ned Dearborn
- **Year published:** 1939
- **Journal or source:** Journal of Mammalogy
- **Full citation:** Dearborn, N. 1939. Sections aid in identifying hair. Journal of Mammalogy 20(3): 346–348.
- **DOI:** 10.2307/1374262
- **Access status:** Publisher link only
- **Where to find it:** https://doi.org/10.2307/1374262

## Tags

- **Species:** Mammals > Brown rat; Mammals > Eastern chipmunk; Mammals > Eastern cottontail; Mammals > Eastern mole; Mammals > Eastern red bat; Mammals > House mouse; Mammals > Little brown bat; Mammals > Masked shrew; Mammals > Meadow jumping mouse; Mammals > Meadow vole; Mammals > Muskrat; Mammals > Northern short-tailed shrew; Mammals > Silver-haired bat; Mammals > Snowshoe hare; Mammals > Southern flying squirrel; Mammals > Star-nosed mole; Mammals > Thirteen-lined ground squirrel; Mammals > White-footed mouse; Mammals > Woodland vole
- **Region:** North America > United States
- **Tracking:** Hair; Tracking; Tracks and signs identification
- **Data type:** Protocol or guidelines
- **Observer qualification:** Not needed
- **Discipline:** Wildlife tracking
- **Year published:** 1939

## Detailed keywords

- **Species:** Studied: guard hairs of 19 small mammals, named in the paper by scientific name only (common names added here): masked shrew (Sorex cinereus), northern short-tailed shrew (Blarina brevicauda), southern flying squirrel (Glaucomys volans), white-footed mouse (Peromyscus leucopus), house mouse (Mus musculus), woodland or pine vole (Pitymys pinetorum), meadow vole (Microtus pennsylvanicus), eastern mole (Scalopus aquaticus), star-nosed mole (Condylura cristata), eastern chipmunk (Tamias striatus), thirteen-lined ground squirrel (Citellus tridecemlineatus), meadow jumping mouse (Zapus hudsonicus), muskrat (Ondatra zibethica), brown or Norway rat (Rattus norvegicus), silver-haired bat (Lasionycteris noctivagans), red bat (Nycteris borealis), little brown bat (Myotis lucifugus), snowshoe hare (Lepus americanus) and eastern cottontail (Sylvilagus floridanus). Several of these 1939 scientific names have since changed (for example Pitymys pinetorum is now Microtus pinetorum, Citellus tridecemlineatus is now Ictidomys tridecemlineatus, and Nycteris borealis is now Lasiurus borealis). Carnivores are mentioned as the animals whose stomachs and excreta (droppings) hold the unknown hairs, but no carnivore species is named. Inconsistency: the figure caption calls all 19 species “rodents and insectivores”, but the list includes three bats and two members of the rabbit and hare family.
- **Location and habitat:** Northeastern United States (the region the 19 species come from). The author’s address is Hilton Village, Virginia. No habitat is described.
- **Topics:** hair identification; guard hairs and underfur; cross sections of hair; optical longitudinal sections; medulla (the central core of a hair) pattern; hair size and shape as identification features; bristles; growth of hair in young animals; camera lucida reference drawings; identifying hairs found in carnivore stomachs and droppings; diet analysis.
- **Statistics or models:** None
- **Data type:** Protocol or guidelines: a short methods note with reference drawings of hair sections from 19 species. No dates of collection, sample sizes or magnification are given; the figure carries a 1 mm scale bar. The text refers to “figures l and m”, meaning drawings l and m within Figure 1.

## Synopsis

### 1. What they did

Hairs found in the stomachs and droppings of carnivores can show what they have eaten, but only if the hairs can be identified. Ned Dearborn set out the structural features of guard hairs from mammals of one region, as an aid to identifying hairs of unknown origin.

He explains that many mammals in temperate and cold regions have two coats. The underfur is made of fine, short, closely packed hairs that shield against cold and damp. Scattered among them are longer, coarser guard hairs, which widen above the underfur to form the outer coat and carry the animal’s colour. The wide part of the guard hair, called the blade, is where the useful features are.

He made camera lucida drawings (a drawing aid that projects the microscope image onto paper) of two views of guard hair blades from 19 small mammals of the northeastern United States: shrews, moles, mice, voles, squirrels, a chipmunk, a muskrat, a rat, three bats, a hare and a cottontail:

- Cross sections: the shape and size of the hair when cut across.

- Optical longitudinal sections: a lengthwise view through the hair under the microscope, showing the pattern of the medulla, the central core of the hair.

### 2. What they found

- The broad part of a guard hair above the underfur can be shaped so distinctively that it identifies a family or even a genus. Size and the pattern of the medulla can also be distinctive.

- Underfur hairs, and the part of guard hairs hidden in the underfur, are more or less round in cross section and have no distinctive shape, so they are not useful for identification.

- Now and then a hair among the normal guard hairs is larger, longer and rounder. The author calls these bristles and says they are of no use in identification.

- Guard hairs of young animals grow larger as the animal matures, but keep the same shape.

- Very often the size and shape of the cross section alone is enough to identify a hair.

- When species have hairs of similar size and shape, the medulla pattern in the lengthwise view is needed. For example, the medulla patterns of the meadow jumping mouse (Zapus) and the muskrat (Ondatra) are far more distinctive than their cross sections.

- Comparing hairs from mammals around the world shows curious peculiarities in some species and interesting parallels in others.

### 3. What they concluded

The author recommends a practical method. In advance, make camera lucida drawings of cross and lengthwise sections of hair from the less familiar mammals of the area. Arrange the drawings in a vertical column and slide them beneath the mirror of the camera lucida, so the image of an unknown hair under the microscope can be laid over each drawing in turn. Because size matters as well as shape, the unknown hair must be viewed at the same magnification as the drawings; otherwise the identification is questionable.

### 4. How tracking was or was not used

No fieldwork or tracking is described. The paper is about one kind of sign: identifying hair, especially hair found in carnivore stomachs and droppings, by its microscopic structure.

### 6. Other technologies, skills or innovations

- Microscope views of hair in cross section and in optical lengthwise section.

- Camera lucida drawings as a reference collection, compared directly against an unknown hair by laying its image over each drawing.

### 8. Implications for tracking (Original Wisdom's observations)

_These are Original Wisdom's observations, not the authors'._

- Hair in scat, on fences or at feeding sites is a common sign. This early paper shows that many hairs that look alike to the naked eye can be told apart under a microscope, and that the shape of the guard hair blade, not the underfur, holds the clues.

- The method depends on a reference collection from known animals of the same area, viewed at the same magnification, which is still the basis of hair identification today.

## Cite this summary

Lawrence, K. 2026. Summary of: Sections Aid in Identifying Hair (Dearborn, 1939). Original Wisdom, Tracking Literature. https://www.originalwisdom.com/tracking-literature/1939-dearborn-sections-aid-identifying-hair/