Expedition to Tierra del Fuego – February 7, 2002
I’ll start with the bad news. Ken and Guy completed the survey of Bahia Lomas finding even fewer birds than they found last year. Red knots declined from 45,150 in 2000 to 29,335 in 2001, and finally 20,755 in this survey. The bird population has fallen so dramatically, we are at a loss to explain the magnitude. It cannot be the result of a catastrophe in Bahia Lomas because the count of Hudsonian godwit only wobbled from 14,030 in 2000 to 27,450 in 2001 and finally 21,650 in 2002. A catastrophe, like an oil spill, would have affected both species. Moreover, we suspect the change in number of godwits is a consequence of the movement of birds between Bahia Lomas and Bahia San Sebastian. Unlike previous surveys, San Sebatian had no red knots in 2002.
We feel sure that part of the reason for the population decline in red knots is a direct result of reduced production of young caused by decreased availability of horseshoe crab eggs on the Delaware Bay. Red knots must double their body weight on horseshoe crab eggs before flying across the largely frozen boreal forest and tundra of Canada to nest. If there are not enough crab eggs, knots either cannot reach the Arctic or don’t have enough energy reserves to lay eggs after they arrive. Without the yearly recruitment of new young, the population has to decline. But the magnitude of the decline we are witnessing suggests even greater losses. We worry that perhaps adult mortality may be increasing as well. Of course this is speculation, but it leaves us more than a little sad to see the changes unfolding so quickly before us.
But some good news came at the end of Guy and Ken’s report. They spoke of a small flock of knots across the Strait of Magellan that might be a good possibility for catching next year. At the time, we were resigned to the catches we had already made and planned to pack up and be out of the camp by 12:00 noon the next day (Tuesday) hopefully arriving in Punta Arenas for an early dinner. When Clive and I heard about 700 birds roosting on a shingle beach on Punta Azul, we knew it couldn’t wait. The next morning we broke down camp, packed the trucks and were crossing the Strait that was as calm as a lake. Under a gorgeous deep blue sky, and not even a breath of wind, we set the nets along the beach edge while knots and godwits gathered on the intertidal mud flat below. The sun shone hotter than any other day of our expedition. We could have worn shorts and short sleeves if any had been packed. It all looked pre-ordained until the birds started having their way with us.
As the tide rose, Godwits, knots, oystercatchers and terns filed onto our beach. Then they all got up and flew around us, tantalizingly setting down close to the catch area then lifting into a puff of smoke that disappeared far down the beach. Mark, Patricia and Mandy twinkled but with little success. Then the whole flocked flew landward across a small river, and all seemed lost . . . . . . that was, until Ricardo made a daring twinkle all his own. He stripped down to his shorts, jumped into the 8 °C (46 °F) water and emerged on the other side running and waving his arms like a crazy man to get the flock back onto the beach. The flock complied, but soon thereafter, lifted from the beach and went landward again. Ricardo returned for a second performance (which we all watched through binoculars). In the mean time, a few oystercatchers started roosted in the catch area so when wayward flock returned, knots and godwits began dropping into the catch area to roost with the oystercatchers. Within seconds, we fired and made the first substantial catch of knot and godwit in Chile, 191 knot and 163 godwit. With a well-deserved feeling of accomplishment and bon ami, the team jumped to action. Within three hours, we processed 354 birds, all of us basking in the warmth of the best weather we’ve had the entire trip. By 7:00 p.m., we were on the road back to Punta Arenas for a very late dinner.
With this large catch, we had fully accomplished our goals. With almost 250 knots banded with Chilean red flags, we now have a sufficient number of birds to observe their movements throughout the flyway. We also have a sufficient sample of birds to make reasonable estimates of percent of adults and juveniles in the population. With future years of data, we can estimate the trend in the production of young birds. Together with other data collected in the flyway, our capture data will help estimate population size and productivity and perhaps answer the riddle of the dramatic loss of birds on Bahia Lomas. This data will become among the most important as the clouds over the red knot’s future gather in coming years.
Our count data presents an entirely new situation for red knots in our hemisphere and a new perspective on the Delaware Bay. Many shorebird biologists share the view that shorebirds are declining worldwide although the data for many species is sketchy. Guy has summarized the Canadian surveys of shorebirds showing that most of the species coming through the Delaware Bay are declining. A few species, like the Red Knot, are dropping quickly. Allan Baker and Patricia Gonzalez, working in other sites in Patagonia, have concluded on the basis of band re-sightings that the wintering population has declined. Surveys conducted by Kathy Clark on the Delaware Bay stopover show declines in red knot numbers over the last five years. This work, done nearly 8,000 miles from home, lends support to these data. Clearly, the situation we have been monitoring for years has taken a more serious turn.
This expedition was a true union between biologists from many countries and a variety of agencies all helping us accomplish our work. We have many people to thank.
Foremost, we thank Jeff Tash, Pete Winkler and Jeff Smith who put together the web site, and to Jeff Tash for the onerous task of posting each report on the site. Kathy Clark helped to bring it all together and helped with logistical problems while we were away.
I personally want to thank Director Robert McDowell and Asst. Director Marty McHugh, New Jersey Division of Fish and Wildlife, and Asst. Commissioner Cari Wild of the New Jersey Department of Environmental Protection for their unflagging support for this project.
The entire expedition would not be possible without the logistical and funding support of three groups. First, Linda Tesauro and Keara Giannotti of the Conserve Wildlife Foundation, which along with the ENSP, provided critical services and support for the trip. Second, Bill Weber and Ingrid Li of the Wildlife Conservation Society provided the bulk of the funding in conjunction with the Geraldine R. Dodge Foundation. Finally, we thank the citizens of New Jersey who buy Conserve Wildlife license plates and Check-Off for Wildlife on their state income taxes.
Our trip included support from several agencies including Allan Baker of the Royal Ontario Museum; the Canadian Wildlife Service; Greg Breece, Cliff Day, and Annette Scherer of the US Fish and Wildlife Service; Mike Harris, Chief of the Nongame and Natural Heritage Section, and David Waller, Director of the Wildlife Resources Division, of the Georgia Department of Natural Resources.
We are extremely grateful to Brian Harrington of the Manomet Bird Observatory for providing the red flags used to color band red knots.
In Chile, we are especially grateful for the hospitality and logistical support of Jorge Jordan. With his help, we were able to bridge the gap between our two countries. We wish to thank Ricardo Olea Celsi, Mayor of Cerro Sombrero, for his assistance and gracious hospitality, Cristina Vargas for organizing municipal support for our activities, and all the people of Cerro Sombrero, llustre Municipalidad de Primavera, for their patience, good nature and support. We especially wish to thank Sr. Ganadera Gutierrez Varillas, the owner of the land on which we set base camp.
Finally, we owe a great deal to Ricardo Matus N. and Olivia Blank H. for all the help they provided . . . . from helping us relate to the people and agencies in Chile to scouting red knot roost sites, their extensive knowledge of the area enabled us to hit the ground running. The entire team thanks Clive Minton whose 50 years of experience in trapping shorebirds, and affable leadership, helped make this expedition a success.
Summary of Birds Banded in Tierra del Fuego, Chile 2002
|South American Tern||61|
|Total Birds Banded||569|
Lawrence J. Niles, PhD
Chief, NJ Endangered Species Program