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Fri, October 5, 2012, 8:06 a.m.

Boulder Weather

Avg. High: 66° F
Avg. Low: 39° F

Max. High: 90° F (1962)
Min. Low: -2° F (1917)

Avg. Precip: 1.49"
Max. Precip: 6.04" (1942)

Average Snow: 5.1"
Max. Snow: 49.3" (1969)

Max Wind: 100

October Wildflowers

Bottle Gentian
(Pneumonanthe bigelovii)

White Aster sp.

Canada Goldenrod
(Solidago canadensis)

Yellow-bellied Marmots spend late summer and early fall days munching on plants and basking in the sun as they prepare for a six-month nap. These burly rodents inhabit every life zone in Boulder County, from plains grassland to alpine tundra.

Oh, for the life of a marmot. Six months nibbling on succulent wildflowers and sunning under the blue alpine sky, and six months sleeping in a snug burrow. Except for a few problems with predators--including Golden Eagles, Coyotes, and Badgers--it seems too good to be true.

Our Yellow-bellied Marmots may double their weight in summer as they feast on grasses and wildflowers, including dandelions, cow parsnips, bluebells, and cinquefoils. They usually enter hibernation in October. During winter torpor their body temperature falls to around 40° F and their pulse slows to four or five beats per minute. They emerge in April, refreshed and ready for another summer of munching and sunbathing.

Social obligations do complicate their day. A typical marmot colony consists of a dominant male, several subdominant females, and young of the year. Marmots that don't belong to a large colony may live singly or in small groups, and some may mate monogamously. Colonial marmots communicate through whistling, screaming, and tooth chattering (to signal aggression). They also scent mark with cheek glands and engage in social play, grooming, and fighting. Sentries keep a lookout for predators, allowing the rest of the colony to forage in relative peace.

Yellow-bellied Marmots (Marmota flaviventris) are closely related to the legendary Woodchuck (M. monax) of the eastern United States. But don't expect them to come out in February looking for their shadows. They're far too busy sleeping.

Other October Events

• Golden-mantled Ground Squirrels, Thirteen-lined Ground Squirrels, and Meadow Jumping Mice also enter into hibernation.
• It's rut season for Moose, Elk, White-tailed Deer, and Pronghorn.
• Uncommon migrants, including Sandhill Cranes and Snow Geese, pass through. Listen for the rolling calls of the cranes high overhead during cloudy days (with easterly winds) around the middle of the month. They're migrating from nesting areas in the northern Rockies to wintering areas in New Mexico and West Texas.
• Western Rattlesnakes converge on communal hibernating sites in rocky hillsides and prairie dog colonies. Dozens of individuals may share a single burrow.
• Brown Trout spawn.

October 2011 Events

October 11: The full moon rises at 6:01 p.m.

• When Elk Bellow (Ponca)
• Falling Leaves ( Cheyenne , Ojibwe)
• Raccoon-Breeding (Osage)

October 21-22: The Orionids meteor shower

October 31: Samhain (Hallomass). At the onset of the Celtic year, the final fruits of summer wither away and winter begins. During this dying time the gates open between the spirit worlds, allowing the dead to walk among us. Spirits of the dead are invited to family feasts and encouraged to warm themselves by the fire while sharing honey, sweet cakes, and beer. Samhain means "summer's end."

Photo credits: Steve Jones, except
White Aster: Tim Hogan

Read Ruth Carol Cushman and Stephen Jones's Nature Almanac column in the Daily Camera "Get Out" section the first Friday of each month.

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