Why Migrate on a Bridge? Monarchs seem to avoid crossing large bodies of water, perhaps because it is dangerous. This means a lake as large as Lake Pontchartrain is an obstacle for migrating monarchs. The bridge gives monarchs a direct way to cross the lake. It is a north/south bridge, so the monarchs can travel in the right direction on their way to Mexico. The bridge may not be safer, however! Here are observations from the field: October 8, 2006 "I travel on Highway 11 each morning to work," says Sally Novatney. "Monarchs follow the bridge road on their way south rather than fly over the water. I drive as slowly as I dare so the wind current doesn't bring them into my car." >> Can you see the bridge, the tiny cars crossing, and the city of New Orleans? Click on the image! More observations (from other places too!) October 18, 2003 "My daughter and I were traveling on the Causeway Bridge, the longest bridge over water in the world, and there were thousands of monarch butterflies. I couldn't imagine why in the world so many butterflies were in the middle of Lake Pontchartrain. Later I researched and discoverd that monarchs migrating and we were in their flight path to Mexico. Awesome!" >> September 28 , 2001 A steady stream of monarchs were migrating south across the Causeway Bridge. According to Joel Lyons, his colleague counted 92 monarchs in the half hour trip from Mandeville to Metairie. Later he tallied 142 monarchs in just 15 minutes. >> Chesapeake Bay, MD "The observation of monarchs using the 24-mile long bridge instead of flying over water in New Orleans is very interesting," wrote Denise Gibbs of the Chincoteague Monarch Monitoring Project . "My team and I have also witnessed monarchs migrating on the Chesapeake Bay Bridge* from Kent Island, MD to Annapolis, MD; and over the Chesapeake Bay Bridge Tunnel from Kiptopeke to Virginia Beach, VA. Unfortunately cars do take a toll on monarchs flying low along the lanes." * Now called William Preston Lane Memorial Bridge People often see monarchs avoiding water. Look for other examples on this Web site. Copyright 2006 Journey North. All Rights Reserved. Please send all questions, comments, and suggestions to our feedback form.