By Steve Mueller
Bird Bones and Air Pressure
Earth is a mixture of lithosphere (solid), Hydrosphere (liquid), Atmosphere (gas), and biosphere (life). Discovering the interactions of the three energy states with life forms is an inquiry process for scientists.
Many people have heard that birds sense weather change before clouds, wind, or other obvious indicators of change arrive. Some have heard that birds may perceive air pressure changes causing a change in their behavior. Personally, I am not observant enough to have noticed these behavior changes. Maybe I do not take the time to watch with a sense of detailed inquiry.
One indication reported by people is that bird feeders empty more rapidly before a storm. Consider doing a family inquiry that would document this by observing the length of time required between feeder filling, when weather is stable and expected to change. Determine if it is different when air pressure is stable and changing. On behalf of the Howard Christensen Nature Center, you may contact me to help you design the family inquiry experiment.
Weather forecasters reported a new record low United States air pressure on Thursday October 28, 2010 and it impressed me physically. In retrospect, I have hypothesized what happened to me and now I empathize more greatly with avian neighbors in my yard.
Wednesday evening I moved light porch chairs to the shed because weather forecasters predicted hurricane force wind gusts were on the way due to rapid pressure change. They said loose items could become projectiles. It only required minor lightweight lifting from me and it seemed within my capabilities. I have seven fractured vertebrae that occurred spontaneously from just moving, because of a blood/bone cancer. I need to be careful and cautious with lifting and even moving my porous bones.
Thursday morning I was experiencing quite severe low back pain in my sacrum. I wondered if I had fractured another bone moving the chairs. My hiking sticks help me maneuver during the day. Family members thought I should see the doctor because it was obvious I was pain with my stooped posture and frequent face grimaces.
The winds howled for two days and by Friday night I was feeling quite fine. I think high air pressure in my abnormally porous bones was forcing its way out to equalize with the big drop in air pressure outside. The force exerted great pressure outward in the bone causing pain. Perhaps the pressure could even crack my fragile bones.
Air-filled hollow bird bones are lightweight permitting easier lift for flight. Bones have a hard outer layer called the periosteum that does not easily permit air movement. I suspect when air pressure changes slightly or greatly, bird bones are more sensitive to change than mammal bones because of greater air space in bird bones. Air pressures tries to equalize and will be especially noticeable when pressure is high inside bones and low outside.
You might compare this with pressure in your ears as you go up or down mountain elevations. A pressure problem is not noticed when walking up or down 3,000 feet because pressure equalizes slowly. Driving is different and we experience ear pain with rapid elevation and air pressure changes. It is even worse if we have congested sinuses.
Birds probably do not normally feel bone pain with normal weather changes. When rapid air pressure changes occur, it may likely be perceived with moderate sensation or pain. I wonder if birds learn to associate bone pain with the coming of a storm and deliberately begin feeding or storing food more heavily. Normally air pressure is a gradual change and should not cause discomfort but it may bring about subtle anatomical sensations that may change bird behavior consciously or subconsciously in nature niches.
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Natural history questions or topic suggestions can be directed to Ranger Steve (Mueller) at the odybrook@chartermi.net Ody Brook, 13010 Northland Dr, Cedar Springs, MI 49319-8433.
616-696-1753.
