Wednesday, January 31, 2007

Chile - Bahia Lomas, Tierra del Fuego, January 30, 2007

We started the day taking care of all the work necessary to maintain a life without all of the amenities taken for granted in our normal lives. Our water must be transported 20 miles from Cerro Sombrero, the nearest, our septic system is a dug latrine, personal hygiene in cold water and dishpans and laundry by hand. At least we’ve had a spate of good weather although it has been frequently punctuated by brief rain showers and stiff cold winds. Still it’s a welcome change from the previous week’s bitter weather.

After lunch on Monday, we made our way out to the Red Knot roost by truck. At four hours before low water, the knots were still feeding on the mussel beds and just starting to roost. On two successive days, we observed only 2,500 knots, not the 5,000 seen in aerial count, a discrepancy that has provoked some discussion. On the previous day, Sunday, we had observed the knots and White-rumped Sandpipers roosting two hours before high and marked a suitable location for the cannon net. We set our cannon net close to the spot, allowing for a 10 inch decrease in the high tide line predicted by the tide charts. We did our best to disguise the net by placing it in a shallow trench and covering it with kelp leaves.

As it turned out, the knots failed to land in the catching area of our net, but with some expert twinkling (gently moving birds towards the net) by Mark and before the rising tide flooded the net, we fired and caught 125 knots, 6 Hudsonian Godwits and two White-rumped Sandpipers. After many attempts, this was our first successful cannon net capture for four years. Despite the fact that we spent the next three hours processing the birds in a bitterly cold winds, the team was pleased. We retrapped several birds that were already banded. These included one bird that had been banded in NJ in May 1998 as an adult. As adults are at least two years old, the minimum age of this bird was 11 years. Therefore, at 20,000 miles a year, this bird had logged over 220,000 migration miles or equivalent to flying to the moon. Other recaptures:

Flag Green Reeds Beach NJ May 21st ,1998
Flag Green North Bowers Beach, DE, May 29th 1999
Flag Lime (puu) Reeds Beach, NJ May 31st 2005
3 Flag Red Strait of Magellan/Bahia Lomas, Chile Feb 5th 2002
Flag Red Bahia Lomas, Chile Feb 8th 2004
Flag Orange unknown origin and date from Argentina

On Sunday, Carmen’s students Gabriela and Sergio began a study of the diet and intake rates of the knots that appear to be feeding mainly on mussels. They are recording the rate at which the birds swallow prey items and will determine the size and type of prey by analyzing the contents of the birds’ droppings.

On Tuesday, Mark and Steve continued observations of the Bahia Azul knot flock, while Humphrey and I investigated the other 5,000 knot roost discovered during the aerial survey. It had been located on the north side of the Straits of Magellan, about 10 km from Bahia Azul. After the 30-minute ferry ride and a few hours of riding the dusty back roads of the grassy steppe surrounding the Strait, we found the shingle spit which jutted 500 meters into the sea. It was surrounded by extensive mussel beds. But we only saw 400 knots. The discrepancy between our ground counts and the aerial count was becoming more and more apparent, so we decided to do a systematic all bay ground count on Wednesday.

Another important objective of our expedition is to develop final plans for the creation of a new center dedicated to the study of shorebirds on Bahia Lomas. We have already had preliminary discussions with the mayor of the municipality of Primavera, Ricardo Olea, who has whole heartedly embraced the idea of the center. Jorge Jordan, a key businessman in Punta Arenas, has already set up a Chilean foundation to receive the money. It only remains for us to finalize the plans for the center and the foundation. Tomorrow we will meet with the Administrator of the municipality, and in a few days firm up on our plans with Jorge.

Monday, January 29, 2007

Chile - Bahia Lomas, Tierra del Fuego, January 28, 2007

After two days of warm sun and a mild wind the weather has turned to wind and cold rain. Good reason to be writing in the warmth of our cook tent. With little communication from the outside world we seem to have lost our sense of the day of the week and date. We just know how much time we have left. These last two days have opened up an entirely new line of investigation that will require all the time we have.

Guy Morrison and Ken Ross completed their yearly flight of the Strait of Magellan and Bahia Lomas to count Red Knots and Hudsonian Godwits. Their survey is yet to be completed as it also includes sections of the Atlantic Coast of Argentina. In our area they found roughly the same number of knots and godwits which is both good and bad news. The good news is that the number of birds has not gone down, the bad news is that they have not gone up. Allan Baker from the Royal Ontario Museum conducted a ground count in Rio Grande and found a significant reduction from his last count in 2006. We hope for the best in Guy and Ken’s count.

Guy also stunned us with the news that most of the birds were not in the area that we would have predicted. In all years past, the knot population divided into two main flocks, about half in the eastern part of the bay and the other near our camp on the western side. But this year a number of events puzzled us. First, we had roughly half of our normal number. Second, after the spring tides they virtually disappeared to the north. On Friday, we found very few knots feeding at low tide near our camp where we had found several thousand in previous years.

From the air, Guy could see two main flocks, one of about 5,000 on the south side of the narrows, not far from the ferry that crosses the Strait of Magellan, and a second of about the same number on the north side about 10 km east of the narrows. This has never occurred in the 7 years of our work here, or the 21 year history of the aerial survey. We were determined to find out why: first to determine whether anything has gone wrong in the normal feeding areas and second to investigate the possibility of a new cannon netting opportunity because the new locations would much more suitable if we could get access to them.

On Saturday, Mark, with Andy the nature photographer in tandem, focused on resightings of marked birds on Bahia Lomas. Humphrey, Mandy, Steve and I searched for the new roost near the ferry. After a nail-biting ride across a mile of beach close to the location where we nearly lost a truck to the tide in 2005, we came to the end of a small sandy/shell pile spit that was literally covered with mussels, many in the size range suitable for red knots. Within a few minutes, we found about 500 knots feeding on mussels. Positively elated, we raced back to camp to get the rest of the crew, especially Allison and Andy to film our discovery. It was their first chance at filming knots feeding close-up. It was the best chance we have ever had of resighting large numbers of marked birds. We spent the rest of the day on intensive resighting. At high tide we counted 2,500 knots on the roost.

This new discovery of knots feeding on mussels in Bahia Azul, as this section of the Straits of Magellan is called, vastly expanded our understanding of the ecology of knots on Bahia Lomas. We now know that the wintering population uses an area much larger than Bahia Lomas itself, including much of the Straits of Magellan on both the north and south sides. We have also discovered that the knots’ diet in this area extends beyond the shellfish (mainly Darina) found in the mudflats of Bahia Lomas.

We look forward to our investigations of the next few days. Our own work of banding and resighitng of marked birds will be made significantly easier now that we have found a large number of knots feeding and roosting in a relatively small area. Dr Carman Espoz of the University of Santo Thomas has arrived with two of her students Gabriela Gonzalez and Sergio Urrejola. They come at an important moment for studies of Red Knots foraging ecology and the invertebrate prey upon which they rely.

Friday, January 26, 2007

Chile - Bahia Lomas, Tierra del Fuego, January 26, 2007

Recovering from a 24 hour day of work would be difficult for anyone, but our relatively high average age and the cold damp weather make sleeping in our tents a chore. We finished processing the birds from our night of mist netting an hour after dawn. Without exception we rose bone-tired, eyes swollen from the nearly constant wind, our clothes in serious need of washing, but we felt satisfied with our progress and anxious to start the day.

We followed the flock of Red Knots that had gathered at high tide for most of the day. One of our purposes is to collect as many resightings of marked birds as possible. With our team banding in the Arctic, Delaware Bay, Atlantic Coast New Jersey and Virginia, Florida and Bahia Lomas and Allan Baker’s team banding in Brazil and Argentina, there are many banded birds from nearly every important wintering, breeding and stopover location. Much can be learned.

For example we have two populations wintering in Bahia Lomas, one in the west near our camp and another in the east side about 30 km from here. This is not unlike the birds wintering in Florida where we know of at least three populations separated by about 20 -40 km down the gulf coast starting near Tampa Bay. In two years of banding and resighting we found virtually no mixing, birds in Tampa Bay don’t appear to mix with birds from Sanibel Island.

This distribution of wintering population has many different implications in both scientific and conservation terms. If it is true that there is no mixing here in Bahia Lomas, we should determine the areas where both flocks roost and feed and present them through mapping. To do this we are following birds from the roost out to the areas they feed, keeping location with GPS as we go. Our resightings will also tell us the extent of mixing between knots wintering here and the population at Rio Grande, 100 km further south.

On Wednesday night and Thursday morning we mist-netted again and made a modest catch of 22 knots, plus small numbers of Magellanic Oystercatchers, Hudsonian Godwits, Two-banded Plovers , White-rumped Sandpipers, South American Terns, and Kelp Gulls. We had no recaptured knots.

We are assisting the Chilean Sevicio Agricola y Ganadero (SAG) our US Department of Agriculture counterpart, in their Avian Influenza investigation. Christian Osorio, the SAG biologist is swabbing every bird we catch as part of a country wide investigation. Our team has been cooperating with USDA biologists in NJ and Florida in a similar US study. Avian Flu experts are testing shorebirds like knots because they breed in the Arctic where birds from all worldwide flyways intermingle to varying degrees. The New World Red Knot breeds in an area of the Arctic just south of an area where knots that winter in the Old World breed. It is theoretically possible that avian influenza could be transferred between these populations and therefore between continents. To date, all these investigations have shown no evidence that avian flu has been transferred in this way. For the last five years, we have been working in Delaware Bay with biologists from the Southeast Center for Disease Control, and all of the testing has shown no indication of avian flu in Red Knots.

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Wednesday, January 24, 2007

Chile - Bahia Lomas Tierra del Fuego, January 23, 2007

We began the day preparing for a cannon net catch of red knots on the salicornia marsh close to our camp. Over the last few days, Knots have gathered in the area during the highest tides looking for a good place to roost. At normal tides the birds spend all their time feeding or roosting along the tide line. But twice in each lunar period, at the new and full moon the high tides rise much higher forcing them to roost ever closer to vegetation bringing them within hunting grounds of predators like the Patagonia fox. These spring tides nearly double the width of the intertidal muds and create a marsh dominated by salicornia which actually stays dry most of the month. This marsh provides our best chance to catch the birds.

Only a short drive from the camp we quicky made our set. We intended to fire a net measuring 22 m by 10 m powered by 3 cannons. We furled it into a 22 m trench to keep its profile even with the marsh surface; we then carefully cover it with bits of salicornia as camouflage. We had observed the knots for several hours on the previous day’s high tide to determine the best place to set the net and decided on an island of salicornia on which the birds took refuge from the advancing tide. We had to make sure they would not be caught over mud because they cannot preen it off and leaves them vulnerable to the damp and cold. After an hour of hard work we moved off.

We established a fire position that allowed us a good view of the catch area but far enough away that it did not disturb the birds. Within the hour, the tide rose high enough to bring in a flock of about 2,000 knots and 7,000 godwits. But it came in much faster and higher than predicted. This tide was to be only 0.1 m higher than the previous high tide so we thought our set would remain dry at high water.

We were wrong. At first, the tide flooded the area and the birds gathered in much the same way as the previous day. But then they started moving out, at first in small groups and finally the entire flock. For a brief period we had about 20 birds in our catching area, but they too left joined the others. Meanwhile the tide rushed in and flooded the net. We were done, but our day was not over, not nearly.

After a quick lunch, we gathered our mist-netting equipment. A mist net is a fine small mesh net that can be stretched between poles and catches flying birds at night when the nets can’t be seen. Normally we would set 20 nets, each about 12 m long. Tonight we decided to set ten at the edge of the salicornia marsh perpendicular to the shoreline. By dinner all was ready.

Nightfall in this section of Chile is very late because of its high latitude. At 1030 while some light persisted in a cold grey sky, Humphrey, Mandy and I inspected the net while Mark and Steve set up the base station where all caught birds would be processed. The wind blew hard from the east promising to increase the height of the tide, but by this time the peak of the spring tide was past and the high tides would start to get lower. We caught a few birds in the first hour, both white-rumped sandpipers. By then the night sky was black and we could only see a hint of our path through the marsh. Then the tide charged over the mudflats.

Within only a few minutes the water rose several feet and the wind blew whitecaps on waves rolling through the catching area. We heard birds hitting the net and, as we found later, over a 100 knots were in the net at once evenly spread out over all ten nets. By the time we got out to the outer net the water was chest-high and filling our waders as we started removing birds from the nets.

Instead of falling as predicted the tide rose another foot with waves even higher. We soon found our selves in a difficult situation. Each bird had to be extracted while keeping balance against pounding waves that would occasionally splash over our chest waders. Each extracted bird had to be moved 200 m back to the base camp for processing though chest deep water, breaking waves, wailing wind and pitch dark. Anyone else would have panicked but the team rose to the occasion and within a few hours all was under control and we had 110 red knots and 6 Hudsonian godwits in the keeping cages. It took us close to three hours to process every bird including measuring, weighing, taking feather samples for sexing and isotope analysis, and of course banding with red flags with unique ids.

We recaptured 10 knots from four countries; four from the Delaware Bay, two from Argentina, two from Chile and one from Brazil:

Fl(PPO) Money Island June 6 2004
Fl(JEV) Mispillion Harbor, May 21 2005
A knot banded at Ted Harvey, Delaware, May 19 2001 recaptured May 29 2002
A knot metal-banded at Reed Beach May 24, 2001
Fo(NW) (Argentina no capture data) recaptured at Mispillion Harbor, May 21, 2003
Fr(CU) Bahia Lomas, Feb 8 2004
Fr Bahia Lomas Feb 2 2003
Fr Bahia Lomas Feb 1 2002
One bird from Brazil and another from Argentina both with no capture records

Mark, Steve and Humphrey have resighted about 40 flagged birds including one white flagged bird banded in the Arctic by our team.

Monday, January 22, 2007

Chile - Bahia Lomas, Tierra del Fuego, January 21, 2007

After traveling nearly 8000 miles over two days we have established our camp at Bahia Lomas on the northern shore of the island of Tierra Del Fuego, just inside the entrance to the Strait of Magellan, close to the Atlantic coast. Over the next two weeks, our small team will determine the status of the population of red knots that spend the northern winter on the Bahia Lomas mudflats.

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!


Chile - 2007 Expedition Objectives

As the shore bird team prepared to depart to Chile on January 18, 2007, they drafted the following objectives for their trip.

From the Shore Bird Team:
The objectives of the Sixth Expedition to Bahia Lomas, are the same as those of our previous trips.

First, we will survey the birds and the conditions in the bay to determine whether either have significantly changed. The state of the Bahia Lomas population of red knots is critical to the Delaware Bay stopover. Our previous expeditions and work in the Delaware has shown that the primary decline of red knots was a result of declines in the wintering population in Tierra del Fuego and nearby Atlantic coast areas. When we first started our work we found over 51,255 birds, by 2006 the number fell to 17,211 birds. During the same period the population of Knots passing through the Delaware Bay fell from 43,145 to 13,455. There are two other areas where knots spend their winters and both are showing similar signs of declines but they account for far less birds.

The second objective of our work is to capture birds. We do this for many different reasons. First to determine the condition of the birds through body measurements, weight, feather molt and lab analysis of feather samples. We then band the birds with permanent USFWS bands and flags that allow identification at a distance with spotting scopes. The flags have unique combinations of letters and numbers that identify the individual. By resighting these birds we can track their migratory pathway, stopover habitats, migratory timing and ultimately survival. Resighting data collected over three years allows us to determine the survival rate for the entire population. The original estimates of survival based on band resightings drove the mathematical model that predicts the red knot extinction by 2010.

Our Third objective is conduct several studies that will help better define the resources important to shorebirds in Bahia Lomas and in particularly the red knots. Several Chilean researchers will join others from Britain and the US to conduct foraging ecology and energetic studies. We will try to determine prey and their availability on the bay.
Our final objective is to help Chilean conservationists to protect Bahia Lomas and the shorebirds wintering on the bay. We have through the Neotropical Bird Conservation Act funds been granted funding to help construct a research and education center on the shore of Bahia Lomas. With the help of our Chilean colleagues we are beginning the process of constructing the center.