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Cliff Dwellers

Striped SkunkThe arresting rock columns and fallen scree provide nooks and crannies used for denning, nesting, loafing and hibernation by a variety of animal species.

Rocky Residences

The refuge is blessed with an abundance of rock, in this case, exposed basalt. You may think solid rock would not make good wildlife habitat, but the basalt is so varied in its particular form, size and position that many species of wildlife find it a great place for a lookout, to hide, or even raise a family. The basalt provides important structure that is generally in short supply in an environment where there are few trees and limited vegetation.

Mammals

About ten species of bats have recently been found to reside on the refuge, at least part of the year. They fly at night, feasting on insects near the abundant water, and hide and sleep by day, deep within recesses in the walls of basalt. One, the canyon bat, even spends the winter here, becoming active on mild evenings. Porcupines, disdaining the cold, find numerous caves and holes for winter shelter. If, while exploring the base of the cliffs, you find the entrance to one of these winter abodes, you will see several inches of dung built up over generations of use. Or perhaps a smaller hole with a distinct olfactory signature will tell of the day-time den of a striped skunk. Yellow-bellied marmots, a large rodent similar to a woodchuck, also pass the winter inactive deep within some recess in or under the rocks. In spring you may hear their sharp whistle floating down from the heights, or see them scampering along a cliff edge. One species you will not see, however, is the bushy-tailed woodrat. Like so many other rodents, they are nocturnal. Their presence can be inferred from the white veneer they deposit on rocks to mark their territories; a rock with an edge, that they can drag their rump over, is preferred. Woodrats make an ample meal for coyotes, bobcat, rattlesnakes, owls and other predators. Even mule deer use the cliffs to their advantage. In winter a southern exposure soaks up the sun and provides extra warmth, while in summer the cliffs provide welcome shade and a sort of camouflage where they are hard to see on a bright sunny day. Other mammals, large and small, find the cliffs, caves and rocks shelter or security.

 

Okay, we've talked about the wildlife that has to work to get up the cliffs. What about those species for which it's effortless? Read on for some surprising facts about birds. 

Canada Goose Nest

Birds

Mammals are not alone in finding security in, or on, the nearly impregnable fortress of stone. Birds make even greater use of this solidified lava, whether keeping a lookout from a dizzying precipice or tending a nest deep within a crack. Two wrens nest and forage in the rocks—the aptly named rock wren and the canyon wren. They both place their nests deep within some narrow crevice, safe from predators. Their song, floating down from the ramparts, is the best clue to their residency on the refuge. The beautiful violet-green swallow also hides its nest within some vertical cliff wall, but the acrobatic adults flitting nearby suggest its presence. Conversely, cliff swallow nests and colonies are quite obvious. Not only do their activity and numbers (50 or more) tell of their location, but their wonderfully constructed mud nests, often stacked one on another, are easy to discern under an overhanging slab of basalt. You may also see a number of these swallows gathering mud for their nests from the edge of Crab Creek or a nearby pond. The Say's phoebe, a type of flycatcher, also uses an over-hanging rock to hide and protect their solitary nest, while its cousin, the western kingbird, places its nest more in the open; it can sometimes be seen clinging to a narrow ledge safely above the ground.

Canada Geese

But one birds seems very out of place on a rock ledge. Canada geese usually nest on the ground, preferably on an island in a lake, but when pressed to reproduce they will go to great heights—occasionally, they will select a flat ledge, high on a cliff, on which to deposit their half dozen or so large eggs. After more than a month of incubation the eggs hatch, and the resultant goslings, light and fluffy as . . . well . . . goose down, tumble off the ledge to one or more of their parents waiting below to make their way to the nearest water. A nest observed recently near the refuge was 40 feet straight above the ground, and the three goslings seen to "take the leap" eventually made their way to the lake nearby. Another goose nest was placed in an abandoned hawk nest situated on a rock ledge (photo above), which already provided much of the nesting material to hold the eggs in place.

Raptors

Many other birds, however, seem perfectly at ease on the cliffs and seem to belong there; these are the numerous raptors that make Columbia NWR home. As many as seven red-tailed hawk nests have been documented on the refuge in the same year; all on a rocky ledge. The rocks around and below will become "white-washed" from the nestlings' repeated defecation. If the nest is in a good location—if the chicks fledge—the hawks will return to reuse it year after year. Great-horned owls will sometimes usurp these nests to raise their own family, or find a cliff ledge or large hole in the rocks to safeguard their nest. Although less frequently seen, barn owls will nest here, too; don't be surprised to be peering into some dark hole or crevice and see a "monkey-faced" owl peering back at you. The large, black common raven frequently seen soaring high over these scablands year round also nests exclusively on a high cliff ledge or hole. American kestrels, a small falcon, will likewise find a hole or depression in the rock to cradle their eggs, while its impressive cousin, the prairie falcon, will require a larger hole or ledge. The former is quite common on the refuge, while the latter, needing more food and a larger territory, are much less common. Both falcons take a variety of prey, with rodents and small birds being common in their diets, and, as we have seen, these species can be found in abundance in and near the cliff walls. Some of these cliff dwellers, birds and mammals alike which are otherwise hard to locate, can be seen early on a cool morning, soaking up the sun on an east-facing rock slope.

 

What about the other wildlife that calls Columbia NWR home? 

Northern Pacific Rattlesnake

Reptiles & Amphibians

If you go exploring the cliffs and scree of Columbia NWR, watch out for western rattlesnakes; they over-winter deep within the cliffs or broken rock beneath. In the spring they stretch out on the sunny rocks to warm their bodies so that they may forage for a meal to break their long fast.

Actually, "listen for" might be a better admonishment than "watch out for"—you can pass within inches of a rattlesnake and never even know he was there, so well-camouflaged are they. Even better still is . . . do both. While our rattlesnakes generally aren't aggressive, nonetheless the last thing you want to do is be bitten.

Other reptiles and amphibians, such as the striped whipsnake or the Great Basin spadefoot toad, hide in the many cracks and crevices along rock slopes, and being cold-blooded, all the reptiles and amphibians not tied to the water can be found sunning themselves on rocks in an effect to jumpstart themselves on cool mornings.

Insects and Plants

Of course, an almost infinite variety of smaller species, many of which are insects, live unseen in the smallest cracks in the rock, in the dung beneath a bird's nest or mammal den, or on the variety of plants that find anchor here. These plants find an abundance of moisture and nutrients essentially funneled into the cracks in the rocks, and the north-facing slopes remain relatively cool and moist, out of the sun and wind. These "micro-climates" support everything from lichens to the four-foot-tall thelypody, a native mustard that seems to grow out of the side of cliffs.

Taken together, all these species of animals and plants have found the refuge's rock walls a blessing of basalt!

Page Photo Credits — Striped Skunk - Jane Abel, Canada Goose Nest - Gordon Warrick, Northern Pacific Rattlesnake - Chuck and Grace Bartlett
Last Updated: Mar 04, 2014
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