Tierra del Fuego: 1/20/08

Our Seventh Expedition to Tierra del Fuego: 1/20/08

Our Friday morning started by saying goodbye to Sergio and Gabriella, the veterinary students from University of Santo Thomas. Their major professor is Carmen Espoz. Carmen left the night before. We were sorry to see them go; they are hard working intelligent people who are always willing to lend a hand. Now we have a team of 7 people, small but adequate.

(Carmen with her daughter Antonia.)

While working on the catch of Magellanic Oystercatchers, Ricardo found a new roost for red knot, the oddest one we had ever encountered. Shorebird roosting sites are usually straightforward. Night roosts are usually far away from land and isolated by water to provide a defensible perimeter from ground predators. During the day they choose areas with good visibility to provide reasonable forewarning of approaching birds of prey.

(Daytime roost of red knots along Bahia Lomas (Photo by Ricardo Matus))

In Bahia Lomas knots and godwits often roost just at the waters edge and roll forward with the advancing tide, until it peaks. Afterwards they move back with the ebbing tide. At Bahia Azul on the Strait they roost on a spit of land between a small river and the sea, and move up and down the slope of the spit. It’s only at the spring tides, those high tides that flood all of the inter-tidal flats, that the shorebirds find the need to roost on the highest ground mostly dominated by two species of salicornia. It is dangerous to be on the salicornia, Patagonian fox patrol it regularly hunting roosting birds.

(Daytime roost of red knots and Hudsonian Godwits on the edge of salicornia on Bahia Lomas during a spring tide.)

Ricardo found the roost at least a kilometer from the high tide line which is amazing by itself. Even more amazing, nearly the entire population of the west side of Bahia Lomas roosted in one small isolated patch of salicornia. 3,000 red knots sat happily only 100 m from the high ground. The reason was the wind.

(Knots roosting in salicornia along Bahia Lomas far from the waters edge)

The previous three days a strong wind from the west blew towards the sea. On Wednesday it blew hurricane force. On Thursday the wind fell to a slightly more moderate 40 mph. On our first visit to the site we found small clusters of knot droppings on the lee side of the salicornia clumps. Such places afforded a little shelter and the proximity of the high ground cut the wind more. At the level of the birds there was virtually no wind.

Knowing all this still does not assure a catch. The wind had died down overnight and was now a more modest 20-30 mph which is high but not abnormal for Tierra del Fuego. More importantly we had attempted many catches on salicornia in the past, all failures because it was just too difficult to set the net in the right position and the birds were virtually impossible to move in the right direction. Could we set our net in the right place? Could they be moved without flying far away? Would the birds return now that the wind had slowed; they might prefer to roost along the waterline.

(Daytime roost along the straits of Magellan at Bahia Azul in 2007)

The team set the net in good time, but it was slow work because we had to hack out a trench for the net in rock hard ground. In the midst of net-setting a small group of godwits and knots flew over our heads swinging around and landing not 200 m from our net. After a chaotic rush to finish setting the net and move equipment, we were ready. In the meantime the 3,000 knot flock had arrived and we began the process of twinkling them into position.

But they wouldn’t move into the catching area in front of the net. This is an area of about 10 x 23 m in to which birds must be induced to go if they are to be caught. Humphrey, Ricardo and I tried repeatedly but the birds would always move from one side of the net to the other, always avoiding the catching area.

Our problem was obvious. To be safe we used very obvious piles of rock to mark the catch area and the danger zone, a 2 meter strip in front of the net that must be clear to avoid hitting birds with the net. We also placed two wooden decoys to draw birds into the area. It was clear that the birds were being put off by the markers and decoys so we removed the decoys and reduced the size of the markers.

Within 20 minutes, we made a catch, a wonderful catch, onefor the records. We caught and processed 201 red knots, and probably caught another 20 or so that made their way out of the net before we could secure it. Although we worked until 11:00 pm processing the catch we went back to camp happy and satisfied because we had met our major objective. Anything else would be gravy.

(Larry, Steve, Humphrey, Ricardo, Gerry and David processing catch of knots. processing catch of knots ( Photo by Mandy Dey))

Tierra del Fuego: 1/18/08

Our Seventh Expedition to Tierra del Fuego: 1/18/08

Guy Morrison and Ken Ross carried out their recount but found no more knots than on their first aerial count of the bay. They plan to fly a third time to confirm the count but already it seems certain that the red knot population in Bahia Lomas has fallen by a further 30% over the past year. It’s premature to ask why, but along with declines in other wintering areas, it appears that the red knot population may be in greater danger than it was only a year ago.

In 2004, a paper published in the Proceedings of the Royal Society in Britain projected that the rufa subspecies of the red knot could become extinct by 2010. Stable numbers over the past few years have suggested that this prediction was unduly pessimistic. In light of this year’s surveys, however, extinction within a very few years seems quite possible. We will know more by the end of the expedition.

Our work goes well. On Tuesday the 15^th we set our net at a new site half way between our old camp along the extensive flats on the west side of the bay and Punta Espora where the Straits of Magellan become narrow. We named the site the Twin Hills minefield after the two small hills that bookend a fenced-off active minefield that borders the beach. The site had great promise (as long as we didn’t attempt to cross the fence!). Guy Morrison and Ken Ross saw knots and godwits there on their Sunday aerial survey flight and we found similar numbers on Monday, but on that occasion we arrived too late to set the cannon net so we decided to attempt a catch there on Tuesday.

(Sign marking mine field behind beach at Twin Hills mine site)

Four peninsulas of rock projecting into the sea make it a perfect roosting site for knots, Hudsonian godwits and Magellanic oystercatchers. A steep beach makes for easier cannon netting because the tide heights are much less difficult to predict than the almost imperceptible slope of the flats across the rest of Bahia Lomas. Using a technique developed by Clive Minton we established the likely level of the next high tide compared with the previous one. It requires two people, one at the old tide line, the other marking a point on their leg equal to the difference in the tides. In this case it was 6 inches. The person at the old tide line must lie down so that one eye is almost on the ground and direct the other person to move closer or further away until the mark on their leg aligns with the horizon beyond. At that point the person stands at the estimated new high tide line.

(Magellanic Oystercatchers and behind them Hudsonian Godwits on the Twin Hills site.)

The team set the net and after some difficulty we caught 90 birds, of which 36 were knots. We caught 50 white-rumped sandpipers and four Hudsonian godwits. The SAG and USDA staff joined us and our processing went fast and well.

(Mike from USDA and Julisa from SAG samping a white rump for Avian Flu)

(Claudio from Wildlife Conservation Society and Daniel from SAG sampling birds for Avian Flu)

(Antonia daughter of Carmne Espoz holding a hudsonian godwit)

The next day a ferocious wind descended on the area. Gauges on the ferry at the narrows clocked hurricane force winds of over 70 miles/hour. Needless to say the wind narrowed our options considerably. In the end we decided to abandon an attempt to catch and spent time at base camp preparing for the following day.

(Mist net blown by wind storm on Bahia Lomas.)

The next day, Thursday, the winds had fallen to a still considerable 30+ mph, a speed that would rule out netting in most places. We decided to go back to the Twin Hills minefield because the roost was in the lee of the hills and the winds, though gusty, would not be a problem. The knots did show up, but soon left, and we were forced to go on to plan B. A flock of over 500 Magellanic Oystercatchers roosted at the site and there was no better time to go after them. After a brilliant “twinkle” by Humphrey and Ricardo, we had 85 oystercatchers in the net. With their bright orange-red bills, yellow eyes and pied plumage, they are marvelous birds in the hand. We soon discovered that they must also be remarkably tough because several had old injuries or deformities that they had obviously learned to live with. One had a foot missing; another had elongated and crossed mandibles; another’s bill bent to the right. In the field, the Magellanic oystercatcher’s call seems high-pitched and thin, but when some of the birds objected to being handled, their calls were ear-splitting. We all enjoyed the experience of getting up-close and personal with such a striking and charismatic species.

(Camouflage net on at the Twin Hills site)

(Humphrey holding a Magellanic Oystercatcher.)

(Ricardo, Mandy and Gabriella processing oystercatchers)

(David holding a Magellanic Oystercatcher.)

Previous entries for this expedition: 1/14/08

1/12/08

Tierra del Fuego: 1/14/08

Our Seventh Expedition to Tierra del Fuego: 1/14/08

Humphrey and I left Punta Arenas early to survey the area along the Strait of Magellan at high tide. We left our comfortable digs at the Hotel Noriega at 7.00 am, leaving the rest of the team to pull together all we would need for the first leg of our three week field trip. Fortunately Jorge Jordan and his staff lent us a hand, gathering equipment left since last year, helping to arrange hard-to-get supplies as well as organizing rooms at the hotel.

(Jorge Jordan and Mandy at Jorge’s Hotel Noriega)

On arriving on the Strait, we found far fewer red knots than we had seen last year. This may not mean much; after 7 years of fieldwork, we have grown used to frequent shifts in their roosting sites and feeding habitats. Last year we documented a significant new roost along the narrows, which was particularly suitable for cannon netting because of the steeply sloping beach. The knots feed on mussels, and move up to the roost site at high tide. The gentle gradient of the wide flats of Bahia Lomas, 6 km from high tide to low tide in some places, makes it very difficult to predict where the 30 ft high tide will ebb. The bay’s 60 mile waterfront creates a second dimension allowing birds to roost anywhere they want making cannon netting virtually impossible.

(Looking out over the flats of Bahia Lomas)

With no birds at the Strait we had little choice but to forego cannon netting and use our mist nets; we did this reluctantly because just as the tide is extraordinarily unpredictable so is the weather. Mist netting works best on dark nights with the nets set over the high tide line. We try to set the nets so that the innermost net is just below high tide and the outmost net lies over water about 3 feet deep. True to their name, when their low tide feeding areas are covered, shorebirds tend to fly over the water parallel to the shoreline as they move to their nighttime roost sites. Mist nets set properly should cross their paths so that the birds are caught in the fine mesh. If the tide floods too far, there is a danger that birds caught on the outer nets will hang low into the water and possibly drown; if the tide stops short of the nets, few birds will be caught because they do not usually fly over dry mud.

(Walking in 70 mph winds on the shore of Bahia Azul)

Fortunately the SAG/USDA team assisted ours and the 12 nets were set in quick time. Unfortunately we caught few birds: 6 two-banded plovers and 5 white-rumped sandpipers. The tide fell short, leaving all but the outer four nets out of the water. But strangely we heard few birds, only the plaintiff whistles of the Magellanic oystercatchers. The raucous nighttime sounds of roosting godwits and knots were altogether missing.

(A Knot feeding on a mussels on the Bahia Azul site)

The next morning, Sunday, Guy Morrison gave us preliminary results of the first aerial survey, a disappointing 8000-10,000 knots which pointed to a possible 30% decline over last year’s count for the same area. With such a low figure, Guy and his counting partner, Ken Ross, decided to confirm the result by carrying out a second count the next day. Guy also told us of a new roost on a beach beside a fenced area with land mines in Bahia Lomas just south of the Strait. We decided to discontinue mist netting and attempt a cannon net catch at the new site.

(Survey plane with Guy and Ken rounding Punta Espora)

Tierra del Fuego: 1/12/08

Our Seventh Expedition to Tierra del Fuego: 1/12/08

Our seventh expedition to Tierra del Fuego began with an early evening arrival at Punta Arenas Airport. This small city has either grown more attractive over the last 7 years or we have gradually awakened to its often subtle qualities. Chile has grown more integrated into the world economic system in the last seven years, even establishing a free trade agreement with the US. There are a few chain stores, but even those give a cosmopolitan feel as they are Chilean or European rather than US. I don’t remember coming across a McDonalds. Gone are the days we needed a satellite phone, cell phones are used widely and at least in Punta Arenas broadband internet access pops up everywhere. All of this has made the preparation for our expedition less difficult and our field work more comfortable.

(Looking out over the shore of the Strait of Magellan towards the Andes on our approach to Punta Arenas Airport)

That said we are still about to face off with one of the most infamous bodies of water in the world. The Straits of Magellan still strikes fear in the heart of serious mariners with its often violent wind storms and fearsome 8-knot currents. This may not sound bad but if you are sailing a sailboat with hull speeds of 7 knots, it mean you go backwards. Even modern tankers with speeds of 15 knots must wait for favorable tides. On the ground we must always keep our eye on the barometer. A sudden plunge forecasts wind storms that can blow down tents or render mist nets useless. Last year a sudden storm at night created a truly harrowing experience as we dealt with a big catch in the mist nets over wind blown tide that threatened birds and biologist alike.

(70 mph winds sweeping the Strait in 2007)

What can be said about the improvements in Punta Arenas cannot, unfortunately be said about the red knot populations. Although last year’s count during northward migration on the Delaware Bay remained unchanged, recent counts on the wintering areas suggest much lower numbers. In November, Dr. Allan Baker, Patricia Gonzalez and Luis Benegas reported a big drop in numbers at Rio Grande in the Argentinian part of Tierra del Fuego with the count dropping from around 3,000 birds to 1,500. The count our team conducted over the New Year on the west coast of Florida proved equally disturbing. Where two years ago we counted over 2,000 knots, we found only 550. Therefore the count in Tierra del Fuego will be critical.

(Knot flock landing on the shores Bahia Lomas in 2007 ( photo by Mark Peck))

So the first goal of our work this year is to continue our surveys of knots. Guy Morrison and Ken Ross from the Canadian Fish and Wildlife Service will carry out an aerial count of red knots in the entire area and we will conduct ground counts in our Bahia Lomas study area. We will also trap knots to top-up the proportion of the population carrying bands in order to support our re-sightings program which is designed to help develop estimates of population-size, survival, residency periods etc. All of this work is only possible because of financial help from the US Fish and Wildlife Service through Brad Andres. Third we will team up with the US Department of Agriculture and its Chilean counterpart Servicio Agricola Granadeiro to catch birds to for the surveillance of avian influenza. We will also train the Chilean biologists to catch birds.

(Cannon net firing in 2007 over red knots at Bahia Azul with camouflage kelp in air.)

An interesting new goal of our trip this year will be to catch Magellanic oystercatchers and band them with color bands to distinguish individual birds at a distance. The “Magic Oystercatcher” aroused the interest of many of our colleagues after Dr. Allan Baker presented a paper on the “Definitive Phylogeny of the Oystercatchers” at the International Wader Study Group conference in France in October. He described three main ancestral groups: the old world oystercatchers, the new world oystercatchers and the Magellanic oystercatcher”. Biologists in both Chile and Argentina intend to focus on this most distinctive of the world’s oystercatchers, so our plan to catch and mark a sample is a contribution to this new study. Similar studies take place in the US on American oystercatchers.

(Olivia Blanc holding a Magellanic Oystercatcher caught in 2002)

Finally and most importantly we will continue to pursue our plan to build “The Tierra del Fuego Bird Observatory”. Much has been accomplished in the last year. With the help of Charles Duncan of the Western Hemisphere Shorebird Reserve Network at Manomet Center for Conservation Science, and the Conserve Wildlife Foundation of NJ we now have sufficient funds to start building. Jorge Jordan in Puntas Arenas has used his business expertise to help develop a new non-profit foundation with a board of directors that will oversee the building of the new observatory. The mayor of the Primavera Municipality Senor Ricardo Olea and his deputy, Senor Herrera, will contribute by arranging to move an existing house to the Bay that will be renovated with the project funds. All the elements will soon be in place to start moving dirt, a dream soon to become reality.

(Site of the Tierra del Fuego Bird Observatory)

To the same end, we have invited the participation of NJ Audubon Society to help create a meaningful link to the US. Dr. David Mizrahi will participate in this year’s expedition for the purpose of exploring a role for NJ Audubon in relation to the TdF Bird Observatory. He too is sending blogs to the NJ Audubon website

This year’s teams includes Dr. Amanda Dey, Senior biologist with NJ Division of Fish and Wildlife, Dr. Humphrey Sitters of the International Wader Study Group, Steve Gates a volunteer who has participated and supported our expeditions to the Arctic and TdF as well as our work in the Delaware Bay, and Jerry Binsfeld a retired railroad man from Canada and a volunteer on our Arctic and Delaware Bay expeditions.