A unique mystery waited for me as I took a late afternoon walk near the tip of the Sandy Hook peninsula, in sight of the entrance to New York Harbor. On a warm mid-July Saturday with a light south wind and clear skies, I spotted a small thin sandpiper foraging for food among the surf and wet sand just above the low tide line.
But this was no common sandpiper. In fact, it was an adult Sanderling (Calidris alba) in breeding plumage with two noticeable bands on its pure black legs – a lime green tag on one leg and a small silver band on another. Immediately two questions rushed into my mind – where did this solitary and seemingly friendless sanderling come from and who banded the bird?
Sanderlings are common spring and fall migrants and winter residents around New York Harbor from Jones Beach and Jamaica Bay to Sandy Hook and Sea Bright. They form flocks of a dozen or more. Seeing several plump birds running up and down a beach is a familiar sight to beach goers and is usually no big deal.
Yet, seeing just one thin sanderling in mid-July with a tag is sort of enigmatic. What story could this small shorebird tell?
After taking several pictures and with tag numbers written down, I immediately went home to do some investigative work. First thing I did was to report my finding to www.reportband.gov, a website run by the USGS Patuxent Wildlife Research Center. Scientists here provide numbered leg bands to bird banders and help manage huge databases of bandings and recoveries in both the United States and in partnership with the Canadian Wildlife Service of many different species of birds.
If you find a banded bird please go to this website to report your finding with the band number, or numbers if the bird has more than one band. Your contact information will also be requested in case there are any questions.
The one problem I have with the service, though, it doesn’t tell you instantly where a bird was tagged. The information can be slow to recover; it might take days, weeks or longer. Bummer!
Spending some time on the web I may have found a speedier answer, though maybe not a correct one. A nature blog called The birding dude reported on a sanderling at Breezy Point in 2016 with a similar lime green tag on one black leg and an equivalent small silver band on another. That bird turned out to be banded in Kent County, Delaware on March 18, 2012. Was my tagged sanderling banded in Delaware as well? Maybe, but I also know that Sanderlings as well as other shorebirds are repeatedly tagged in various locations along Delaware Bay, including at Moores Beach and Reeds Beach in Cape May County. I will just have to wait to find out for sure.
In the meantime, this information still doesn’t explain why the bird I spotted was solitary and skinny. I do know that sanderlings are common coastal shorebirds, often found from North America to southern Chile or southern Argentina. They regularly conduct intense long-distance migrations from their wintering grounds along temperate and tropical sandy beaches to breed on High Arctic tundra, far above the Arctic Circle on rocky areas close to lakes and ponds. In North America the Sanderling’s breeding territory generally includes the islands from Banks and Victoria Islands in the west to the Province of Nunavit and northern Hudson Bay in the east.
Fall migration frequently begins in late July and can extend through October. But the lone Sanderling I spotted at Sandy Hook was seen in mid-July. What gives?
An article about shorebird migration at the Black Swamp Bird Observatory in Ohio by Kenn Kaufman, of the Kaufman Field Guides fame, might provide an answer. He writes:
“Most of our migratory shorebirds nest in the Arctic, where the breeding season is quite short, which helps to explain their early southward movement. Some may head south in June if their first attempt at nesting fails, because there may not be time, in the brief Arctic summer, for a second attempt. In a number of species, one member of the pair will leave before the young are full-grown (or even before the eggs hatch), leaving the other parent to finish raising them. For all of these reasons, adult shorebirds of many species begin to show up in Ohio by the end of June, and the fall migration is in full swing before the Fourth of July. Juveniles of most shorebird species migrate later than adults. There is often a full month between the peak passage of adults and the peak passage of juveniles.”
Kaufman goes on to write that southbound adult Sanderlings begin to appear by mid-July along the immediate shoreline of Lake Erie. Could the lone Sandy Hook Sanderling be a victim of a failed nesting attempt in the high rocky tundra or a parent finished raising its young?
I know that much of migration for Sanderlings is often accomplished in long non-stop flights between key stopover points to rest and refuel. Everyone knows that the Sandy Hook peninsula and other urban parks are important pit stops for migrating birds to rest and feed during long journeys. Even the hardcore birders at the Cornell Lab of Ornithology agree. They tell us that migrating birds do not avoid human development to rest and refuel, but use agriculture and urban areas nearly as often as sites more vegetated.
So putting everything together, I think right now the lone tagged sanderling I observed at Sandy Hook was probably banded somewhere along Delaware Bay. The bird was probably a victim of a failed nesting attempt either by the weather or a predator during the short Arctic breeding season or it may have departed before the young were fully grown to leave parent responsibilities to another adult sanderling. The bird was flying fast to southern wintering grounds when it decided to make a pit stop at Sandy Hook. When I found the little fatigued and famished bird it was searching for food, mostly sand crabs and other small invertebrates, and a safe place to rest.
Each year, many birds battle various dilemmas and difficulties to give rise to another generation. It’s a huge gamble with the odds often against them in an ever-increasing manufactured and changeable world. For sanderlings, the global population trend is not known, but the population is not believed to be decreasing sufficiently or rapidly to approach the thresholds under the population trend criterion (>30% decline over ten years or three generations), according to Birdlife International. But more research is needed, and this is why people band birds. Information provided to scientists at www.reportband.gov will help provide a wealth of vital information about the life history of shorebirds including life span, reproductive success and population growth.
The mystery of the Sandy Hook tagged sanderling is not solved yet. Thankfully the bird is still alive and kicking to continue telling its story another time.
To view more pictures, video, or stories of wildlife around Sandy Hook Bay, Raritan Bay, and Lower New York Bay, please visit my nature blog, NY Harbor Nature at http://www.nyharbornature.com