Goshawk Ridge sky
Michael Morton

Goshawk Ridge sky by Michael Morton

Boulder is located where the Great Plains abruptly end and the Rocky Mountains begin. The land rises from 5,000 feet above sea level to over 14,000 feet, and as a result there is an amazing diversity of plants and animals within a relatively small area. There are over 700 species of trees, shrubs, flowers, grasses and ferns on Open Space and Mountain Parks (OSMP). These lands provide critical habitat for some of the most diverse wildlife in all of Colorado. Come explore this unique mosaic of ecosystems.

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Monthly Nature Almanac - May

Hike of the Month: South Boulder Creek West/Lower Big Bluestem

Flowers along Lower Big Bluestem in spring
Sarah Hill

Flowers along Lower Big Bluestem by Sarah Hill

The South Boulder Creek West and Lower Big Bluestem Trails put on a wildflower show in May, including wild irises along Lower Big Bluestem. Both trails provide lovely views of the foothills – you can do either trail as out and backs starting from the South Boulder Creek West Trailhead, or add in a short stretch of the Mesa Trail to form a loop a little over 4 miles. Heading out on South Boulder Creek West provides gorgeous views of the spring green leaves of cottonwoods along the creek. These are excellent trails to explore the grassland ecosystem and the lower range of the ponderosa pine forest. Mule deer commonly graze this area in the early morning. Coyote and fox can also be observed. The area also provides hunting grounds for many of our local raptors. Cooler spring mornings and afternoons are a great time to visit the South Boulder Creek West area – there is very little shade so it can be quite hot in the summer.

Baby Prairie Dogs in May

Watch for baby Black-tailed Prairie Dogs this month. Although the babies were born in late February, they remained underground under the strict care of their mother, who had to protect them from other prairie dogs. Strangely, female prairie dogs will look for any opportunity to destroy the young of other females, even close relatives as long as they remain in the burrow. But as soon as the babies emerge into the sun, females appear to forget their differences and cooperatively suckle each other's offspring.

Many other baby animals will be born this month, including Chipmunks, Skunks and Mule Deer.

Prairie Dogs

Tents in the Bushes

In May, look for small silken tents in chokecherry and wild plum bushes around OSMP. The tents are the communal homes of Eastern Tent Caterpillars, furry spotted larvae that grow up to be tan-colored moths. The tents help protect the caterpillars from predators, especially parasitic wasps and flies that would lay eggs on their bodies; and also help trap humidity and solar heat to keep the larvae warm. Early in the morning, you may see a host of caterpillars basking in the morning sun just below the outermost silken layer of the tent. When they are warm enough, the caterpillars exit the tent en masse and begin eating the host plant’s leaves. As soon as they are full, they retire to the warm safety of the tent to digest their meal in peace. They may feed two or three times a day.

As the caterpillars grow, they continue to add to the tent, gradually making it bigger. When they are ready to pupate, they leave the tent and crawl off by themselves to find a safe location in a crevice or under a stone, where they spin a small silken cocoon. They hatch out as adults several weeks later. Adult moths are very short lived, and are unable to feed themselves. Males may survive for up to a week, but females die after laying their eggs. Tiny larvae begin to develop in the egg masses during the summer, but become dormant and wait through the fall and winter before hatching the following spring.

Tent caterpillar moths provide food to a wide variety of animals, including birds, bats and other insects. The damage they do to the shrubs is usually minimal. Please do not tear down the tents or interfere with the caterpillars: they are one of the many fascinating animals that makes OSMP so special.

What April Showers Brought

Blue Mist Penstemon

May is wildflower month! Hiking on just about any trail will introduce you to some of the beauties of the season. On the prairie, you'll see fields of Golden Banner, some of the first small White Fleabane Asters, white and purple Larkspur, yellow crowns of the parsley-like Musineon, and the tiny flowers of Ball Cacti. In moist areas, look for the lavender blooms of Wild Iris and delicate pink Shooting Stars. Higher in the mountains, you may still find patches of Spring Beauty and Rocky Mountain Candytuft but before long these will be replaced by large patches of azure-flowered Blue Mist Penstemon. But watch out: Poison Ivy is starting to leaf out as well.

Myrtle Spurge - a Brutal Beauty

Myrtle Spurge

During May, the cheerful yellow flowers of Myrtle Spurge, or Donkeytail Spurge, begin appearing in gardens all over Boulder. This plant is one of the state's most invasive noxious weeds. Its cultivation is illegal in Colorado and citizens in Boulder should remove it, or could face a fine. This insidious pest creeps from home gardens onto Open Space land, where it is nearly impossible to eradicate. If you want to help Colorado's ecosystems, start by removing any traces of Myrtle Spurge from your property-- but wear gloves. The plant produces a very toxic latex sap which can burn skin and cause agony if accidentally rubbed into the eyes.

Going Native

Once you have ripped all the Myrtle Spurge out of your garden, you can learn how to garden with Boulder's native wildflowers. There are many local species that make fine additions to your yard: ground cover, large blossoms, shrubs and trees. They have been growing in this climate untended for thousands of years, so they easily shrug off the worst weather Boulder can dish up. Drought? No problem. OSMP staff who have gone native in their own gardens have created an extensive plant list with species-specific growing tips. Dare to go native.

You can also go for a guided Nature Hike with an OSMP naturalist to get to know some of our most beautiful residents.

The Last Word

"Teaching a child not to step on a caterpillar is as valuable to the child as it is to the caterpillar."

- Bradley Miller

Meet Some of OSMP's Rarest Residents

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