[This is part three of a series of posts featuring photos from our March programs in Yellowstone with Natural Habitat Adventures and Wildlife Expeditions of Teton Science Schools].
|American Dipper courtship posture.|
When I first came to the Yellowstone Ecosystem, there were a couple species I really wanted to see. At the top of the list was this peculiar little bird, the American Dipper. They live along rivers and creeks in the Rocky Mountains from Canada down into Mexico, and forage on a prey that nothing else has figured out quite how to access. It's the entrepreneur of the animal kingdom. For every potential food source, there is something that will eventually figure out how to eat it. Insects breed, lay eggs, hatch, grow, metamorphose, and thrive all over the rocks in turbulent mountain streams. But except for the dippers, nothing has quite figured out how to eat them. Sure, trout wait downstream for bugs that get peeled off their feet by the swift current, but dippers go right to the rocks and pick off insects directly.
|Hunting for insects in the creek.|
In a great example of a burgeoning evolutionary trajectory, the Dipper has very few adaptations for its lifestyle. He is a songbird, just like a thrush, a tanager, a waxwing, or a robin. He has no webbed feet or dagger-like bill. What he does have is oxygen-rich blood and a slow metabolism for life in cold water, not to mention some waterproof preening-oil. His biggest asset is its charisma. He dives into the water, paddling the rapids with his wings, sometimes popping up fifty yards downstream, on the other side of a class II or III rapid!
When he does emerge, he usually does so with a bill full of stoneflies and caddisflies. In the nesting season, he might take these insects and fly right through a waterfall to get to his nest on a dry ledge behind the cascade. If there are other dippers around, he will storm out from behind that waterfall and karate-kick the intruder right into the water.
He perches on rocks along the shore, bobbing (dipping) up and down, trying to look like the moving water behind him. "Bird and stream, inseparable," as John Muir said. A female lands nearby, his dipping speeds up, and he starts to sing. His rambling warble sings on and on without pause, almost mimicking the musical sound of the proverbial babbling brook. She starts dipping up and down too and pacing around on her rock. Both birds take off and chase each other over the stream, up into the trees, into the sky, and back over the water, splashing down together right in the middle of an eddying pool.
Watching these dippers along the Gardiner River over the last two weeks was mesmerizing. One of those little jewels in nature you would only find if you already knew where to look.
|Gardiner River, and the Boiling River hot spring steaming towards the background.|