On my last day, I descended from the spruce forests of the eastern Cascades to the sage-filled coulees and arid canyons of the Columbia River valley. I arrived at Moses Coulee just after dawn, and the air was cool and filled with the aromatic smell of sage. I was looking for sage specialists here, especially Sage Thrasher and Sage Sparrow. (Sage Grouse don’t live here, but I plan to look for them further west in March when they are at their breeding lek.) Sage Sparrows are habitat specialists here in Washington, preferring healthy tracts of Big Sage – and Moses Coulee is one of a relatively few places which feature a protected stretch of this habitat.
At first it was nearly silent, but eventually I was able to get good looks at the thrasher, sparrow, and a couple of Rock Wrens (another target species of the morning). By now it was warming up, and the kestrels were flitting around the cliff tops. The forecast called for triple digits temps today, so I decided to hit a few other places before my brain started baking.
My next stop was Dry Falls, just south of Grand Coulee dam. This was not really a birding stop (although I did pick up some hawks circling below me), but just a break to admire the view and stretch my legs. My picture (below) simply does not do this area justice (unfortunately the view is to the east, and it was still morning so the photo is backlit).
Dry Falls is what remains from the biggest waterfall ever discovered on the planet earth. About 15,000 years ago during the last great ice age, huge continental ice sheets reached down from the pole to cover much of northern North America. One arm of this massive glacier reached out over modern-day Idaho and formed a giant ice dam that blocked the flow of westward-draining rivers. The water backed up behind the dam, eventually forming a giant lake – what geologists call Glacial Lake Missoula – which covered much of western Montana. At its peak, Glacial Lake Missoula contained as much as 500 cubic miles of water. (Envision a cubic mile of water for a minute. For comparison, Lake Washington contains about 0.7 cubic miles of water.)
At some point, the enormous amount of water behind the ice dam suddenly broke free, and those 500 cubic miles of water were unleashed across eastern Washington in a cataclysmic flood. The water blitzed over and through the landscape at 60 miles per hour, with flow rates averaging 10 cubic miles per hour. The entire lake emptied in a couple days, its water carving out many of the notable geological features of eastern Washington including the coulees, pothole lakes, and canyons that are collectively referred to as the “Channeled Scablands.”
Dry Falls was a raging waterfall then, almost four miles across with a 600 foot drop. By comparison, Horseshoe Falls (the largest and most impressive part of Niagara Falls) is about half a mile wide and drops 170 feet. It’s maximum flow rate is between 1000 and 10,000 times less than the amount of water that coursed over Dry Falls during the great flood. Crazy. If you’re ever in the area, check it out – it’s just south of Grand Coulee Dam, just off of US-2.
On with the birding! I stopped at Potholes Reservoir just south of Moses Lake to look for shorebirds, and was rewarded with a passel of goodies, including dowitchers, yellowlegs, plovers, Baird’s Sandpipers, and a couple of relatively rare Stilt Sandpipers. I met a very knowledgeable birder from Spokane who helped me puzzle out a few of the more challenging IDs. By this point it was afternoon, the sun was sizzling, and I had a long drive home, so I packed up my spotting scope and headed west. Eastern Washington was a treat, and I’ll be back later on this fall or earlier winter.
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