Connections: Birds and Crabs, Part V

Although upwards of 30 different species of birds may crowd the beaches of Delaware Bay, there are four primary shorebirds that use the Bay as a stopover area during their northward migration.  Red Knots, Semi-palmated Sandpipers, Ruddy Turnstones, and Sanderlings make up approximately 97 percent of the birds that visit these shores.  Let’s take a look at each of these distinctive species.

            Red knots have an average wingspan of about twenty inches (this is slightly more than the distance from the tip of your middle finger to your elbow) and an overall length of approximately nine inches (a distance slightly longer than that from the tip of your middle finger to your wrist).  Their backs look like a psychedelic checkerboard – a crazy assembly of mottled buff, streaks of black, and bits of white in a seemingly haphazard pattern.  Their distinctive name comes partly from the fact that much of their head and all of their belly is robin-red.
            Red knots winter along the southern coasts of South America, primarily in Tierra del Fuego (Spanish for “land of fire,” and discovered by Ferdinand Magellan in 1520).  During its breeding season the Red Knot inhabits the mainland and islands scattered across the Arctic Circle.  Take a look at a globe and you will quickly appreciate the incredible distances it has to fly each year - 9,300 miles from south to north every spring and 9,300 miles from north to south every autumn (that’s an annual journey of 18,600 miles – a distance equivalent to three-and-a-half round trips, by car, between Los Angeles and Washington, DC).  As you might imagine, this bird is regarded as one of the longest-distance migrants in the animal kingdom.«
            Red knots migrate in enormous flocks – gatherings that are considerably larger than most other shorebirds.  Most migrating birds tend to cover enormous distances in one fell swoop (pardon the pun); however, red knots tend to segment their journeys into sections of about 1,500 miles at a time.  As a result, they tend to having “staging areas” – specific landing spots along the entire Atlantic coast.  They will use the spots regularly (just like you might travel to the same vacation destination year after year) – stopping in the same places at approximately the same times year after year.  These favorite stopping off points are familiar territory for the red knots and they can anticipate the available of food at each location.  On the downside, however, these sites make the bird susceptible to poaching, severe habitat change, and endemic diseases and toxins.  As an example, red knots were heavily hunted in the early 20th century, and have never fully recovered in parts of eastern Canada. 

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« A red knot banded in May 1987 was identified again on Delaware Bay in May 2000. During the intervening thirteen years, it was estimated that this single bird flew approximately 242,350 miles, a distance greater than that between the earth and the moon (the average distance between these two celestial objects is 238,855 miles).