Natural Selections

Wild or free roaming burros and horses are protected by Federal Law as "living symbols of the historic and pioneer spirit of the West.” A few miles south of the historic swinging bridge crossing the San Rafael River, a group of 10 burrows grazed on a rolling plain beneath hills...

Social systems of great blue herons vary dramatically, from solitary nests to large heronries, and some heronries include nests of great egrets and cattle egrets.

The sharing of vigilance and alarms by golden-mantled ground squirrels and yellow-bellied marmots is not unique.

Great egrets usually hunt in shallow water, stalking small fish, which they swallow whole.

An understated characterization of quaking aspen is that it grows in many different plant communities, in many different ways and has adapted to an extremely wide range of environments.

Trilobite beetles are perhaps the most bizarre of all the net-winged beetles Some insects are cryptic, blending in with their backgrounds to hide from predators, while others are brightly colored, noisy, or form dense and conspicuous aggregations to warn their predators away. Red net-winged beetles, Dictyoptera aurora , are exemplars...

Dusky grouse are effectively camouflaged and cryptic much of the year, but when it comes to the spring mating season, the males are bright and bold.

Evolutionary biologists have found fossil evidence of 110 species of pterosaurs, with wing spans ranging from 10 inches to over 33 feet I scout potential sites for camping and photography trips by looking at maps and reading about landscapes and habitats, so I was optimistic that I had found an...

With dry air and clear skies, people in the west have much greater opportunity to enjoy the light shows at dawn and dusk and celestial phenomena. Following are comments and details, each starting with a question about mechanisms.

Boulder residents were acutely aware of the wildfires, for they had been breathing smoke since the Pine Gulch fire started near Grand Junction on July 31. But the proximity of the CalWood Fire and the sight of roiling smoke rising and forming pyrocumulus clouds at the northern edge of Boulder brought the terrible threat home.