Migrating common loons appear on prairie reservoirs. A flock of 80 was reported on a small lake near Boulder Creek west of Erie on Tuesday.
Great horned owls begin to court in cottonwood groves on the plains. Listen for their mellifluous hoots around dusk and dawn.
Snow geese pass through on their way south toward the Texas Gulf Coast and wildlife refuges in western Texas and New Mexico.
Mule deer and white-tailed deer spar and mate.
The first time we heard the sound of fir cones clattering down through the conifers, we imagined that a black bear had climbed into one of the trees and set to work dismantling it, branch by branch.
When we realized that all the commotion was caused by a 7-ounce pine squirrel, we gained new respect for these pint-sized bundles of energy.
A single pine squirrel can clip hundreds of cones per hour, and this harvesting activity continues from late summer through fall. When the coast is clear, the squirrel scurries down to the forest floor where it gathers the clipped cones, one by one, and buries them in middens -- loose piles of cone scales, cores of eaten cones and intact cones.
This larder sees the squirrel through the winter. When hungry, it digs up a cone, nibbles away its scales and consumes the protein-rich seeds. During the warmer months, the squirrels also subsist on buds, berries, leaves of plants and mushrooms.
One midden we found on the flanks of Green Mountain measured 30 feet long, 5 to 10 feet across and up to 2 feet deep. Its guardian scurried back and forth on a bare pine limb, chattering and squealing at any mammal or bird that passed within a stone's throw of its cache.
Throughout the winter, the cones and cone scales in the middens slowly decompose, releasing heat. Mice, voles and other rodents burrow down into this cozy environment to sleep away the coldest months. Weasels dive and slither through the middens, seeking out rodent prey. Oregon grape and other succulent plants take root. Without intending to, the industrious squirrels have created a unique ecosystem on the forest floor.
Pine squirrels (also known as "chickarees," for their querulous calls, and "red squirrels" in the East) range throughout North American montane and subalpine conifer forests. Though our Front Range squirrels do harvest pine cones, they more often frequent groves of Douglas-fir or Englemann spruce, possibly because larger Abert's squirrels chase them away from the ponderosa pines. In the foothills, we find the greatest numbers of pine squirrels among dense stands of Douglas-fir.
The fierce territoriality of these little squirrels renders them amazingly bold around humans. Don't be surprised if, while walking through the woods, you're occasionally bombarded by falling cones.
Pine squirrels breed from mid-April through early summer, producing two to five young. Young squirrels leave the nest -- a globe-shaped tangle of leaves, twigs and grasses high in the conifers -- when they are about 40 days old. Their predators include pine martens, red foxes, lynx and various forest hawks and owls.
The amount of racket made by territorial pine squirrels informs us of the condition of the forest. During years of abundant cone crops, the squirrels go about the business of harvesting and storing cones with relatively little fuss. During years when cones are scarce, the squirrels become more and more querulous. Scientists say that periodic cone crop failures may have a greater impact than predation on pine squirrel populations.