Delaware Bay 2007- Scanning for Shorebirds on Delaware Bay
You can tell the beginning of the season on the Delaware Bay not only by the arrival of shorebirds but the shorebird biologists. In one day, at the Philadelphia International Airport, we retrieved Pablo Lobera Alvarez and Victor Ayala Perez from Mexico, Humphrey and Philippa Sitters from the UK and Clive Minton, Susan Taylor and Peter Fullagar from Australia. Pablo and Victor study ecology under Dr. Roberto Carmona of the University of Baja California Sur. They have come to the Bay to help us and learn how to catch shorebirds to carry out similar work in Mexico. Dr. Peter Fullagar has studied shorebirds, waterbirds and waterfowl in Australia for over 50 years including one study of shearwaters still ongoing after 48 years. Drs. Sitters and Minton are core team members.
The first project we needed to get started was the resighting of individually banded birds. Over the last four years we have banded knots, turnstones and sanderlings with alpha-numeric leg flags that can be read with a spotting scope at a distance so as not disturb them. Relocating marked bird dramatically improves our understanding of both population dynamics and behavior. A marked bird that is repeatedly resighted yields valuable understanding about how long they live and, if enough birds are resighted, demographic information about the entire population. Last year, our scanners relocated over 60 percent of all previously banded birds.
But every time someone goes to scan a group of birds, there might be a bonus. Over the last three years, our team and others have banded birds not only on the Delaware Bay but also on the Atlantic Coast of NJ (lime green flag on upper left leg), in Florida (lime green flag on upper right leg), Brazil (blue flag), Argentina (orange flag), Chile (red flag), and Canada (white flag). Seeing a bird in the Delaware Bay, just arrived from Chile with a brilliant red flag — telling you all that is known about that bird, is a special treat for all. One bird from Florida was resighted 12 different times!
The repeated resighting of individuals tell us much about their migratory routes and the timing of their arrivals and departures from all the places they stopover on their migration. This past year we worked with Yves Aubry, a Canadian Fish and Wildlife biologist, on the Mingan Islands, an archipelago in the Gulf of St. Lawrence, Quebec. Yves found a significant number of knots stopping over there on their way south from the breeding areas in the Arctic. He and his assistants resighted over 500 individuals with flags, and from this data, we determined that mostly South American red knots stopped over on the Mingan Islands, each for about seven days.
Most of this work is being carried out by volunteers, and every year more and more join the team. In recognition of this, we are trying to start a new website for online reporting of marked birds through the Cornell Lab of Ornithology’s E-Bird web site. The new site will allow volunteers to report resightings, find out where else the bird has been seen and where it was originally banded. An added bonus for volunteers is the use of digital cameras attached to spotting scopes to record resighted birds. The pictures are so good that you can read the band combination and numbers off the picture. This new technique known as “digiscoping” is rapidly becoming a worldwide pastime. I have attached some digiscope pictures to the blog.
The resightings program depends on regular banding of new birds which is an integral part of our program. On Monday, we trapped 71 ruddy turnstones and 58 sanderlings and one red knot and on Tuesday we focused on knots and caught 48 knots 28 turnstones and 76 sanderlings. More about that in the next blog entry.
Editor’s note: due to computer issues, we’re unable to post photographs. We hope to resolve that issue in the next couple of days.