It was one of those inquiries in which the search for an answer opens some interesting new facts, understandings and revelations.

The question: What is the eyeshine color of pine martens?

The revelation: Bernie McHugh has in his library a reference book titled “Wildlife Damage Inspection Handbook,” third edition, by Stephen Vantassel. This is a reference used by people charged with the removal from highways, etc., of road-killed animals whose identity is not easily made.

The answer: Eyeshine of pine martens is blue — electric blue.

The eyes of many vertebrates have a layer of tissue that lies immediately behind the retina. It is called the tapetum lucid, and its function is to reflect visible light back through the retina, increasing the light available to the photoreceptors of the eye. The tapetum lucid contributes to the superior night vision of some animals.

Not all. Most primates, including us, don’t have a tapetum lucid.

Quoting from Wikipedia: “Eyeshine is a visible effect of the tapetum lucid. When light shines into the eye of an animal with [this tissue] the pupil appears to glow. Eyeshine can be seen in many animals in nature and flash photographs. In low light a hand-held flashlight is sufficient to produce eyeshine that is highly visible to humans (despite our inferior night vision). Eyeshine occurs in a wide variety of colors including white, blue, green, yellow, pink and red. However, since eyeshine leads to iridescence the color varies slightly with the angle at which it is seen and with the minerals which make up the reflective tapetum lucid crystals.”

Blue eyeshine occurs in many mammals; white in many fish. Green eyeshine occurs in mammals such as cats, dogs and raccoons, and famously in wolves; red eye shine in coyote, rodents, opossums and birds. See below for a partial listing arranged by color.

Field Notes: As a saying has it: An interesting winter season. Considerable bare ground in the middle and southern parts of Jackson Hole; OK snow cover on upper elevations; March coming in like a lamb; a need for a warm jacket in mornings but maybe just a sweater by noon.

March, and Canada geese pairs are showing up near traditional nesting areas — including a goose pair that years ago took possession of an osprey nest along the Snake River’s Swinging Bridge south of Jackson (Roman Kravetsky, Feb. 28). Great blue herons are returning, singly. Bald eagles are in various stages of courtship, nest repair and egg laying.

Linda Soper welcomed a half-dozen evening grosbeaks on Feb. 26 on West Gros Ventre Butte. Ben Hahn reported a half dozen redpolls, first of the season.

The first report of a blooming wildflower, orogenia, has come in. Roman Kravetsky called it in from the field.

A few red-winged blackbirds came and maybe went (Garrett Seal, Denny Emory, a couple of others). And a coming-into-breeding-plumage house finch feeding a sunflower seed to a willing female. Aw, shucks.

Bert Raynes©2015

Bert Raynes writes weekly on whatever suits his fancy with a dash of news on nature and its many ways.

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