Aerial Bridges: Birds that Span Continents


owl at Muir Woods

For thousands of years, birds of all shapes and sizes have followed signs and signals that humans still do not understand to travel between wintering and breeding grounds. Not all birds migrate, but those that do may voyage very far. For example, the Red Knot, a medium-sized shorebird, makes one of the longest yearly migrations of any bird, traveling 9,300 miles every year from its Arctic breeding grounds to southern South America. (And don’t forget—it also flies back!)

Migratory birds rely on their wintering and breeding grounds for suitable habitat and food sources, but during their travels they must have access to stopover sites to refuel. For the Red Knot, the Delaware Bay on the East Coast is a major staging ground during spring migration; it is estimated that over 90% of one subspecies can be present in a single day.  These stopover sites throughout the Americas are of vital importance to the survival of migratory birds—on an individual level as well as for entire populations of species.

For 20 years, people all over the Americas have been celebrating these feathered world travelers.  Migratory birds link the people and lands of their nesting grounds in Canada and the United States with those in their non-breeding ranges in Mexico, Central and South America, and the Caribbean. Through education, International Migratory Bird Day (IMBD) aims to bridge the gaps between citizens and scientists of countries separated by many thousands of miles, as migratory birds span the continents with their flights. 

In the Golden Gate National Parks, Muir Woods has been hosting a free IMBD event for 12 years—and on May 12, 2012 the community is invited back to celebrate IMBD’s 20th anniversary! Activities include mist-net demonstrations with the Point Reyes Bird Observatory, bilingual bird walks and story times, beach cleanup at Muir Beach, family crafts and games, and the opportunity to talk to local bird- and wildlife-conservation groups. You can also sample shade-grown coffee and chocolate, and meet a live Northern Spotted Owl at 1 pm! A shuttle from Muir Woods to Muir Beach will be provided. Parking will be limited, so plan to take the Muir Woods shuttle from Mill Valley, where it picks up every 30 minutes.

Come to IMBD and learn more about migratory birds and enjoy some pristine habitat that has already been preserved for future generations of both birds and people! For more information, call the Muir Woods ranger station at (415) 388-2596 or visit

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