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Fri, Dec. 3, 2010, 8:06 a.m.

Boulder Weather

Avg. High: 45° F
Avg. Low: 22° F

Max. High: 75° F (1965)
Min. Low: -24° F (1990)

Avg. Precip: 0.77"
Max. Precip: 4.20" (1913)

Average Snow: 13.0"
Max. Snow: 52.5" (1913)

Max Wind: 120

December Wildflowers

Gumweed (Grindelia squarrosa)

Early Easter daisies
(Townsendia hookerii and T. exscapa)

A new late-fall tradition in Boulder County is the annual appearance of one or more trumpeter swans on prairie lakes and ponds. The swans usually show up just as the last open water is freezing over and most waterfowl have headed farther south.

Trumpeter swans disappeared from most of the prairie region during the first two-thirds of the 20th century. By the 1950s these majestic birds had grown very rare. Protection from hunting, along with reintroduction programs in the northern Rockies and northern plains, have helped populations to recover.

Several hundred pairs now nest in the Greater Yellowstone Basin, the Dakotas, and the Nebraska Sandhills. Several thousand pairs nest from western Alaska south and east into the Canadian prairies. In December look for migrating trumpeters, and an occasional stray tundra swan, at Boulder Reservoir, Baseline Reservoir, Sawhill Ponds, and Lake Valley Pond.

Other December Events

• Early Easter daisies (Townsendia hookerii and T. exscapa) begin to bloom on south-facing shales in foothills canyons.
• The Boulder and Longmont Christmas bird counts are held during the last or second-last weekend before Christmas. New volunteers are always welcome: www.boulderaudubon.org
• Mule deer finish up sparring maneuvers and begin shedding antlers. Bighorn sheep continue dueling on high mountain escarpments.
• American dippers migrate down from the mountains to fish for aquatic insects in Boulder and St. Vrain Creeks. Look for them along the Boulder Creek Trail just north of Walden Ponds.
• Pasture sage and fringed sage leaf out on sunny hillsides.

December 2010 Events

December 7: Approximate date of the latest sunset in Boulder County. The sunsets begin getting earlier after this date, but the sun rises enough later that the shortest day is at the solstice

December 13-14: The Geminid meteor shower.

With an average of 100 meteors per hour radiating from near the bright star Castor, this end-of-the-calendar shower is usually one of the year’s best. For this year's performance, we'll have approximately a first-quarter moon, which will wash out many of the meteors before midnight. Geminid meteors come from 3200 Phaethon, an asteroid discovered in 1983. (Reference)

December 21: Winter solstice occurs at 12:51 p.m. MST. Join BCNA members for our annual Winter Solstice sunrise hike on White Rocks Trail the following morning.

December 21: Full moon rises at 5:15 p.m.

• Frost on Lodge (Lakota)
• Popping Trees (Arapaho)
• When the Deer Run Together (Cheyenne)

Photos: Steve Jones

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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