Delaware Bay Shorebirds, Cape May, NJ (Great Blue Virtual Tours)

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May 26-June 1, 2012

Delaware Bay Shorebirds, Cape May, NJ

Posted by Don Crockett on June 5, 2012

I spent last week with the Delaware Bay Shorebird Project Team and the shorebirds in Cape May, NJ. I shot quite a bit of shorebird video and took some panoramic images of 2 separate shorebird banding sessions. I've included a shorebird video and 2 panoramic team images below.

Video of Delaware Bay Shorebirds at Cape May, NJ

Video showing Red Knots, Ruddy Turnstones, Semipalmated Sandpipers, and Sanderlings.

The first time I visited Cape May to see the Horseshoe Crab/shorebird phenomenon was in 1997. After that visit I wrote a fairly extensive web article about the looming crisis facing the shorebirds due to the overharvest of Horseshoe Crabs, "Shorebird Crisis: The Horseshoe Crabs of Delaware Bay". After 15 years, I was interested in updating the article to report how the efforts to help the Horseshoe Crabs and shorebirds had progressed. Over the years I had read various reports but hadn't followed the research closely. Once the data is available for this season I'll work on an update page for the web article.

I arrived at Cape May on Saturday, May 26th looking to video shorebirds at Reed's, Cook's, and Kimble's Beaches. Unfortunately for me the Red Knot count in the area went from 12,000 on Friday to less than 3,000 on Saturday as reported by Larry Niles on the Celebrate Delaware Bay Facebook page. A baywide survey on Sunday revealed that these birds hadn't just vacated the Cape May area, they had left for the Arctic. Fortunately for the Red Knots and other shorebirds this was the best year for weight gain since 1998. Weather conditions in May were ideal for Horseshoe Crab spawning along the Delaware Bay shores which meant there was a plentiful supply of food for the shorebirds. This was one of the earliest mass departures for the knots. A day late and 9,000 birds short for me, but 3,000 knots is still an impressive number. Over the course of the week the numbers of knots continued to dwindle.

The above video shows a variety of clips I shot from the three beaches. The clips are mainly of Red Knots, Ruddy Turnstones, Semipalmated Sandpipers, and Sanderlings. The clip of the airplane flushing the shorebirds was part of an aerial survey to count the birds along the Delaware Bay shores. There is also a short clip of Horseshoe Crabs spawning.

Click to enlarge to see flag code.

The banded Red Knot that appears at 3:14 in the video has an orange engraved flag with "PT" on it. I logged the resighting at report.bandedbirds.org and did a "Map Your Resighting" search and found that the bird had been resighted previously at Wreck Island, VA, on May 27, 2007 and at Mispillion Harbor, DE on June 1, 2007. I also learned from the site that an orange flag indicates that the knot was originally banded in Argentina and that 2 alpha codes were used on Argentinian birds banded in 2002/2003.

Shorebird Team, May 28, 2012: 360° Interactive Panoramic Image

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Shorebird Team, May 28, 2012): High Resolution 360° Panoramic Image

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The Delaware Shorebird Project Team has 3 main activities: counting, banding, and spotting. They are counting the numbers of different species of shorebirds to see how the numbers of shorebirds using the bay is varying over the course of the season and from year to year. For banding they use nets launched by small cannons to capture shorebirds so they can be weighed, measured, sampled, and banded. How the weights progress over the course of the few weeks that the birds are along the bay is particularly important since the birds need to gain enough weight to fuel their migration to the Arctic in time to breed. Spotting involves using scopes to record banded birds and log resightings of flags whose color indicates where a bird was originally banded and whose alphanumeric codes identify individual birds.

Click to enlarge map from Philadelphia Inquirer article.

A recent addition to the banding operation is the use of light-sensitive geolocators for some of the Red Knots. A light-sensitive geolocator is a tiny electronic package that costs around $250 and is attached to a Red Knot's leg. The electronics regularly log time, light intensity, and whether the sensor is wet. Sunrise and sunset are used to determine the length of the day which can be used to calculate latitude. Splitting the sunrise/sunset times determines "noon" which can be used to calculate longitude. Light intensity can also be used to determine when a female is incubating eggs. The packages have enough battery power and storage to log data for 1-2 years. The birds need to be recaptured to retrieve the geolocator and its data since there is no way with today's technology to build a package light enough for a Red Knot to carry that can transmit the data. So recapturing knots with geolocators is a major target of the cannon netting.

47 geolocators were attached for the first time in 2009. Hundreds more have been attached since then. The team has been able to retrieve around 15% of the geolocators it has attached, and information gleaned from the travel logs of the birds has been extremely useful in learning about stopover sites and details of the nomadic journeys of individual birds. See the map to the right that appeared in a Philadelphia Inquirer article from 2010 "Geolocators show red knots' flights extraordinary". This map was generated using 1 year's worth of data from one of the first geolocators that was retrieved. The map shows an amazing non-stop 5,000 mile flight from southern Brazil to North Carolina in 6 days.

I went out with the banding crew on Memorial Day, May 28th to photograph the team in action. The cannon net was set up, eggs were dug up and spread on the beach in front of the net as bait, and then we waited out of sight for the shorebirds to accumulate. The cannons were fired when a Red Knot with a geolocator was spotted within the capture area. This bird was extracted from the net and kept separate from the other birds so it would be processed carefully. Dozens of knots were captured in addition to the geolocator knot as well as dozens of other species of shorebirds. A big surprise was that a 2nd knot with a geolocator had been captured, it wasn't noticed until it was pulled from the holding box to be processed.

The panoramic image above shows the banding operation that takes place to process the shorebirds after they have been captured. The work is divided between subteams gathered in circles. Each circle processes a different species with each team member performing a different task: data recording, banding, measuring bill and head length, weighing, and feather sample collection. The group under the green canopy was taking separate samples from birds processed by the other subteams. They were taking blood samples, swabbing, etc. for use in investigation of avian influenza and other research purposes.

The panoramic image below was shot when I went out with the shorebird team for a 2nd day on May 29th. Fewer birds were captured on this outing and no geolocators were retrieved. A reporter and photographer from the New York Times were reporting for A Bird, a Crab and a Shared Fight to Survive that was published in the Times on June 6, 2012.