Under Construction Mary 2011


Erethizon dorsatum

GUARD HAIR (secondary, as the primary are quills?)

Length: up to 110mm (Mayer 1952), 40-60mm (Adorjan and Kolenosky 1969), 101-181mm (Moore et al 1974), 85-100mm (ASM #1)  135mm, quill 35-52mm (ASM #2) 160mm max, around 50mm near belly (ASM #3)

Diameter Range: 247-615 microns (Moore et al 1974, says they are not including quills), 87.5-175 (ASM #1)

Medullary Index: 0.66 to 0.78 (three from ASM#1).

Medulla: Lack of prominent compounding seen in most rodents? The medulla changes along the width of the long guard hair. Overall medulla is continuous and looks a bit like fish scales. Where the hair is closest to the root and appears macroscopically as a thick white hair, the medulla is composed of many rows of compact fish scale like cells (many side-by-side across the width of the medulla).  These can look a little bit like “honeycomb” medulla cells of certain hoofed animals.  As the hair tappers and becomes darker, the medulla is very difficult to see, however, in locations of lighter pigmentation it is possible to see fish scale-like cells arranged in rows of between 5-6 cells across width of the medulla. On average the cells are wider than they are high. (ASM #1) Medulla may be even wider on the intermediate sized hairs.

Color: Reddish-brown coloration seen throughout the cortex and the medulla (ASM #1). Dark brown throughout the cortex and medulla (ASM #2)  Base may be white, then black band, then 12-60mm yellow band and finally a black tip. (Moore et al 1974) Banded, with white tip around 35mm on some examples.  There are 3 segments to banding, with base and trip white or pale and middle of shaft black. Black band by far the biggest band. (ASM #3)

Scales:  Torn paper-like scales with many pointy jagged tips per scale. (ASM#1)


Length: 40-60mm (ASM #1) 30-40mm (ASM #2) 20-25mm (ASM #3)

Diameter Range: 25-40 microns (ASM #1) 72.5-82.5 microns (ASM #2)

Medullary Index: 0.3 (ASM #1), 0.86 (ASM #2)

Medulla: 15 microns wide (ASM #1). Medulla is continuous with one cell spanning the width. The cell shapes are irregular globular cells (similar to Nerd candy).  The very finest underfur hairs have no medulla.

Color: Streaky brown throughout the cortex and medulla.

Scales: Stacked crowns

Macro Qualities: 25.5 -35.5” long (Forsyth 1999).  Animal is 25-31” long.  Guard hairs have lighter tips.  Belly hair sparse, ranges from brown to black (ADF&G 2008).  Long, kinky dull brown reddish or chocolate-colored underfur.  Guard hairs are long and a very pale yellowish white.  Quills are short and hidden under the underfur (have to part the underfur to see them) except in the butt and tail area.  Tummy, face and chin seem to only have underfur. (ASM #1)

Cultures: For example: Athabascan (ADF&G 2008).

Notes: ASM #1 is from a taxidermy mount made for the eagle tree exhibit by AARRKK Taxidermy.  ASM #2 is from a collection of loose quills and hairs in the ASM conservation lab. ASM #3 is courtesy of Mike Etnier (zooarchaeologist, Applied Osteology) from gunflint trail, Cook County, Grand Marais, Minnesota, from the midline of the back and from the left front leg.

Troubleshooting: a complicated-looking medulla in the underfur may help ID porcupine, who have a wide medulla with lots of pigment, although beware: the porcupine underfur may also have a very long tapering tip with no medulla.


Range: Mostly in the Interior, Kenai Peninsula and Panhandle. (Forsyth 1999)  All of Alaska except Alaska Peninsula, Kodiak, Nunivak and St Lawrence Islands (ADF&G 2008) 

Names: Order Rodentia (the rodents)

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