Saturday, September 10, 2011

cliff swallow mud nests

cliff swallow mud nests
clinging in colonies to 
limestone river bluffs

We put in at Daley's Bridge, an arched iron bridge rusted with age, and now we are mostly just floating with the fast current down the Upper Iowa River. Though shallow, the clear water is moving swiftly enough that paddling our light-weight Kevlar canoe is optional. We employ our bent shaft paddles to navigate riffles, horseshoe bends and trees that have fallen across the river, their roots undercut by spring flooding. The leisurely pace gives us plenty of time to enjoy the scenery as we pass by in slow motion. The river has carved "entrenched meanders" through bedrock, with 100 foot vertical limestone walls on the outside curve and floodplain forest on the inside. The cliffs consist of layer upon layer of fossils laid down by ancient seas. The chalk-white escarpments host balsam firs, red cedars and white pines, distinctly different from the willows, maples, oaks and cottonwoods growing along the low shoreline. The cliff overhangs offer protection for nest colonies of cliff swallows. Common summer residents in Iowa, cliff swallows breed as far north as Alaska and winter as far south as Argentina. Arriving in late April, they have already finished migrating by this time of year, early September. As we flow past the cliffs, we see many colonies of nests, some still intact, others half obliterated. The swallows build their nests with pellets of mud they gather in their mouths. They use little reinforcing material such as straw or hair, so the nests are vulnerable to rainstorms. Each nest is shaped like a squat clay bottle with a downward protruding neck, which functions as an entrance to the interior chamber, sparingly lined with grass, hair and feathers. Both parents build the nest, which takes one or two weeks. As a potter, I am enchanted with these round pots cobbled together and plastered in clusters on vertical stone. Now I want to come back in early summer, to watch the graceful swallows catching insects on the wing and feeding their young in their charming earth shelters.

No comments:

Post a Comment