By PATRICIA SIMPSON
If you haven’t seen a song sparrow (Melospiza melodia) in your backyard, you have probably at least heard the bird’s famous song. Most often, the first four notes resemble Beethoven’s Symphony No. 5. While a song sparrow may be dismissed as just another LBJ (little brown job), it is easily recognizable by its dark brown streaks on the chest, dotted by a dark brown spot in the center of the breast.
Mission Trails Regional Park trail guide Millie Basden recently came upon a song sparrow bathing on the west edge of Lake Murray as seen in her iNaturalist observation found at bit.ly/2pkBHUd.
Bathing is a favorite activity for birds. It helps clean the feathers from debris and parasites. In one of Basden’s photos, we can observe beads of water rolling off the back and the tail of the bird, reminding us that ducks and geese are not the only ones enjoying nice waterproof feathers.
Ever wondered why birds don’t get soaked? The most common theory is that birds reach a special gland near their tails with their beaks while preening. The gland, called the preen gland, secretes a lipid rich oil that birds apply to their feathers for waterproofing. While this theory has merit, many scientists now agree that the feather structure is key to repelling water. Several experiments consisting of removing any oil residues from feathers while maintaining their structure have shown that water is still repelled in the absence of the oil.
In the book “Feathers: The Evolution of a Natural Miracle,” co-author Thor Hanson explains that scientists are still arguing about the mechanics of water repellence and feather structure. Is it the density of the microstructure of feathers or the pockets of air contained in that same microstructure that help ward off water? Many physicists, engineers and inventors are paying close attention to the research. The results may lead to groundbreaking, environmentally-friendly, lightweight, and extremely efficient new waterproof material. Stay tuned!
— Patricia Simpson is a trail guide at Mission Trails regional Park.