Wildlife Wednesday - Changing Of The Guard

By Andy Ames

For Mule deer of the Estes Valley, September marks the changing of the guard — guard hair that is. Gone is the reddish-brown summer coat and in comes winter’s grey. While color is important in thermal regulation (red is more reflective, while grey absorbs heat) the two coats vary in other ways, too. The summer coat consists of short, thin, densely packed hairs. This aids in water repellency while also protecting from biting insects. To stay cool, deer change their activity patterns by resting in the shade much of the day while foraging during the cooler hours of dusk and dawn. In winter deer dress in layers, a soft wooly undercoat is protected by long, hollow guard hairs. This combination provides enough insulation that snow can pile up on the backs of deer without melting. For additional warmth, deer take advantage of the sun and are more active during daylight hours while seeking protection of the trees at night. With the autumnal equinox just days away, Mule deer will be well prepared.

Molt almost complete now. The grey winter coat is growing in while summer’s reddish coat is almost entirely shed away.

Mule deer summer coat consists of a single layer of short, thin, densely packed reddish-brown hair — excellent for reflecting light to help stay cool and keep bugs at bay.

A young buck transitioning from his winter to summer coat. Young, old, or unhealthy deer tend to retain their coats longer. This buck still had quite a coat of winter guard hair in mid June while larger bucks nearby were already in full summer mode.

Here is the Estes Valley winter coats get a lot of wear. In mid June this new mom’s summer coat is just growing in. By mid September, after just 3 months, she will be sporting a new winter coat.

A soft wooly undercoat covered by long, hollow guard hairs comes in handy in these conditions.