Saturday, January 28, 2012

Dippers In Love

This week I went for a walk at the Little Qualicum River fish hatchery. This site is well known for an American Dipper nest which is built underneath of a bridge. This nest, which is a lovely little domed fairy hut made of green moss with a round opening near the bottom, has been active for at least 15 years that I know of, and produces young year after year after year. As American Dippers all look more or less the same, there is no way of knowing if these are the same pair that originally built the nest. Given the typical life span of a passerine, it is pretty doubtful.
One of the interesting things about this particular nest site, is how early courting and nesting begins compared to others in the area. I have been monitoring about a dozen American Dipper nests in the Mt. Arrowsmith Biosphere region over the past few years, and most are just beginning to incubate eggs around the time that birds from this nest fledge. This might be due to how rich the immediate area downstream of the hatchery is, but determining that for certain would be a major research project all of its own!
As soon as I stepped out of the car in the parking area of the hatchery earlier this week, I could hear the clear song of a dipper coming from the spawning channel, just a few meters upstream from the bridge and nest site. Carefully peering over the railing, I saw two American Dippers teetering on a small rock near the edge of the channel. The one highest on the rock would sing it's long, varied, liquid song, while the lower bird appeared to ignore it. Then the singing bird would leap off the rock into the water, and fly to the bottom. I say "fly", because this is essentially what they do. Although most aquatic bird species use their legs to propel them underwater, dippers use their wings, stroking along underwater in what looks like slow motion flight. When they reach the bottom, they then hop along on their legs, reappearing on the surface a few minutes later, where they will either take flight to the shore, or bob along the surface using swimming with their legs like a tiny duck.
When this particular dipper popped back up onto the surface, it began making some very excited calls, and then flew to the rock where the other bird was waiting. It then sang another long and complicated song, this time with its mouth full of some tiny aquatic invertebrates! The other bird suddenly dropped onto it's belly, tilted it's head back with its bill wide open, and began fluttering it's wings and vibrating its body slightly, much as a fledgling would when it was being fed. The other bird took the cue, and hopped over and stuffed it's bill full of food into the begging birds mouth. A second later, they were chasing each other up and down the spawning channel with excited calls and partial songs. Before I left, I saw one bird carrying some moss under the bridge, carefully tucking it into the existing nest under the watchful eye of the other bird. Clearly, courting is already well underway for this pair of American Dippers!

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