Continental gyre of birds.

A paper published this week by scientists at the Cornell Lab of Ornithology uses eBird data to map the migratory paths of birds in the Western Hemisphere. eBird is a free online checklist program used by tens of thousands of bird watchers. The database now has millions of observations from across the world, most of them in North America. This latest study used 6.1 million eBird checklists to find the “center” of bird species’ ranges through the year. The summary below shows, for 118 species, how these centers move. Each point is one species, tracked through checklists over a year.

bird map

A pattern emerges: birds tend to “loop” clockwise, migrating north in the spring overland through Central America and Mexico, then flying south in the autumn over the Gulf of Mexico and the Atlantic. These loops are caused by prevailing winds, especially the northeast trade winds over the ocean. Turn, turn, turn: sung by the Byrds.

To my eye, deviations from the pattern are just as fascinating. Why do some species veer so far east? Why do some linger in the south, then zip north in a rush? A map with each dot labelled by species lets us peer into these mysteries.

To write honestly and with conviction anything about the migration of birds, one should oneself have migrated. Somehow or other we should dehumanize ourselves, feel the feel of feathers on our body and wind in our wings, and finally know what it is to leave abundance and safety and daylight and yield to a compelling instinct, age-old, seeming at the time quite devoid of reason and object.” — William Beebe


11 thoughts on “Continental gyre of birds.

    1. mefurr

      So amazing. Really shows the value of those eBird checklists!
      Speaking of birds, my co-worker at Atlanta Audubon tells me that we’ve invited you to speak this spring during our Bird Fest. I hope you can make it! Reading your book and hearing you speak during my Master Naturalist class (3 yrs ago) was a positive influence in my life. You were so gracious, too, to allow AWARE Wildlife Center (where I volunteer) to share your chapter on coyotes. I’ve been observing some pretty regularly here in Atlanta–so thrilling.
      Best wishes for a happy, healthy 2016. Hope you can make it for Bird Fest!
      Melanie Furr

  1. Cara Grant

    David, that’s beautiful… thanks for sharing! And by the way, Hi… and love from all the Granties!!! 😄

  2. John Salmond

    For me, this is a particularly striking case of what a good teacher or a good book can do: take something you already in general terms knew and bring it to a different level, so you know it in a new way, internalise it in a new form

  3. Pingback: Why the Bird Sings | Bee Happee Now

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