Fall's Journey South Update: September 25, 1998
Today's Report Includes:
|White-throated Sparrows migrate at night Photo courtesy of Lang Elliott|
Twinkle, Twinkle, Little Compass
Those stars disappear on foggy, rainy nights, and many birds become lost in the darkness. Imagine finding your way through your classroom, or through your school, or through a strange building, blindfolded. A sudden fog puts a tiny warbler in this predicament, over a strange land and literally up in the air, sometimes not knowing how far down the ground is until it crashes.
Where's a Fog Horn When You Need One?
Without the familiar stars acting as a beacon above, birds lose their sense of direction. The magnetite in many of their brains helps give them a vague, general direction, but stars are so much more important for their orientation that the moment they spy any light in the fog, they head straight for it. One Journey North staff member has been a licensed bird rehabilitator. Every time she had hurt warblers in her office, loose so they wouldn't injure feathers on cage bars, they rested quietly at night after the lights went off. But if she turned on a light in the darkness, they instantly flew up right smack into the light! In a small room (and her office was tiny) birds couldn't build up enough momentum to get hurt. Outside, birds crashing into communication tower lights and lighted buildings are moving fast enough to bonk hard. Concussions and broken wings are the result.
How to Respond to Today's Challenge Question # 4:
Dead Birds DO Tell Tales
Many businesses don't understand how dangerous their lighted buildings are to migrating birds. If they understood the problem, many would cooperate in helping birds by turning lights off. Michael Mesure founded an organization called FLAP that tries to document the problem, persuade people in charge of large buildings to turn the lights off or pull window shades and blinds at night during migration, and save as many injured birds as possible.
Michael Mesure told Journey North that FLAP has been making good progress this year. Windows of the tallest structure in Toronto, which were 48% lit last year, are down to 14% lit. This building has THOUSANDS of windows, so this is a big reduction in lighting! And it proves that other buildings can do the same. Migrating weather has been very good this year, with clear skies and moonlight on many nights, so "migrants are migrating at their highest altitudes. We're picking up about half-dozen to twenty birds a morning. A few mornings they haven't found any, which is great."
|Image courtesy of FLAP|
Reminder: Fall Migration is Underway Please turn off your lights when leaving work in the evening if you work in an office tower.
Discussion of Challenge Question # 3
The minimum distance between Nova Scotia and the British Isles is about 2400 miles, depending on the exact sites you measure from. (We used Cape Sable and Ireland.) A Blackpoll Warbler would be flying about 110 degrees off course to end up there rather than passing the Bermuda Islands? There are many possible ways a bird could end up so far off course. A powerful storm could blow it off course. It could have started its flight under overcast skies, and never properly gotten its bearings. It might even have had assistance from humans--as it flew over the ocean, it might have been attracted to a ship's lights, and stayed with the ship throughout the passage.
The Next Journey South Update Will Be Posted on October 2, 1998