Chile - Bahia Lomas, Tierra del Fuego, January 21, 2007
When our studies began in 2000, we found more than 50,000 red knots and 26,000 Hudsonian godwits (both pictured at left) spread throughout the length of the Bay. The knot population was evenly split into two main groups, one on the southeast side of the bay, and the other on the northwest side. Last year, the Bahia Lomas population fell to an all time low of 9,000, 2,000 in the southeast and 7,000 in the northwest. In contrast, Godwit numbers have remained stable.
The rufa subspecies of the red knot, which mainly winters in Tierra del Fuego, has been declining for the last five years, mostly because Delaware Bay horseshoe crabs have been overharvested leaving the birds without the resources they need to migrate to the Arctic and breed successfully. It is hard to believe that this bleak Patagonian landscape is vitally connected to our lush countryside of NJ; even harder to think that an insignificant commercial harvest 8,000 miles away could cause so much damage.
We arrived in Punta Arenas at noon on Friday 17 January, quickly purchased supplies for our two-week expedition and drove three hours to Cerro Sombrero, near the western end of Bahia Lomas, crossing the Strait of Magellan on the way. Our team is lead by Dr. Larry Niles with the Conserve Wildlife Foundation of New Jersey and includes Dr. Amanda Dey with NJ Fish and Wildife, Dr. Humphrey Sitters with the International Wader Study Group, Ricardo Matus a self employed Chilean Biologist and Steve Gates, a volunteer from NJ. Within a few days, we will be joined by Mark Peck from the Royal Ontario Museum and Dr. Carmen Espoz, a professor from University of Santo Thomas in Chile.
Alarmingly, our first count here at Bahia Lomas on Saturday 20 January suggests not only that there has been no recovery of the knot population, but there may have been a further substantial decline. We spread out along the northeast shore of the bay for a preliminary count, mostly to determine the best place to focus our work. At midday we counted only 2,000 red knots where there has been 7,000 in 2005 and about 7,000 Hudsonian godwits. We made our count over high tide, when all the shorebirds are forced to roost along the shoreline.
The amplitude of the tide in Bahia Lomas is 5 times greater than in Delaware Bay. Each day, the sea rises and falls about 8 meters on neap tides and 10 meters on spring tides. What attracts the knots is the shellfish found in the 5-km wide inter-tidal mudflats. On the day of our survey, the tide flooded the entirety of the mudflats reaching the extensive beds of salicornia that surround the bay. The birds follow the tides in and out, feeding most of the time that the flats are exposed. At high tide, when they have no access to their food, they gather in flocks along the shoreline. That is the best time to count them.
Over the next few days, we will take advantage of the high spring tides tides to catch a sample of knots as part of ongoing studies of their lifecycle and survival. We will use cannon nets by day and/or mist-nets at night. The weather and tides in Bahia Lomas make catching difficult, but the stakes are high and we are very determined!
Labels: red knot counts