Expedition to Tierra del Fuego – January 29, 2002
To bed at 12:00 a.m., we were all out on the flats by 6:30 a.m. trying to find roosting red knots. With virtually no wind, all birds roosted out on the tidal flat at the water’s edge. We made our way out to the flock of 5,000 knots and 10,000 godwits and scanned 10 birds with bands, seven were from the Delaware Bay. We returned to this roost area of isolated salicornia hummocks in a very dry mud flat. We set two nets, camouflaging them with salicornia and the dry mud so that the 20-meter net and cannons blended reasonably well into the surrounding habitat. We returned that evening to the “salting”, or salicornia marsh, and to our surprise the birds had returned in fairly large numbers. Unfortunately after a long twinkle (gentling walking or even crawling to move the birds into a position close to the net) by Mandy and Mark the birds stayed away from the catch area and eventually left. In a test firing of the cannons, however we found that with all the weight of the net and camouflage, two of the cannons were severely under powered.
Clive, Mandy, Ricardo, Olivia and I drove into Cerro Sombrero to find a machine shop to fix the cannons. We needed to drill the cannon barrel wider so it could hold more black powder. Cerro Sambrerro is a very small town with 100’s of miles or grassland in all directions. As odd as it may seem we found a very suitable machine shop in the ENAP (national oil company) building. Arturo Delgado and his supervisor Carlos Navarro were willing to help, and within an hour we had two cannons with 50 percent more capacity for powder. While the cannons were being drilled, Olivia and Ricardo met with the children of the Cerro Sombrero middle school and the mayor of the town to arrange for the kids to join us in our work. They accepted and planned to come in a few days.
Armed with a suitable set of cannons, we once again set up our nets at the salicornia roost. The birds were using it more frequently now. After a lot of twinkling we made a shot with over 70 birds in the catch area but only caught about 20 because our other set of cannons fired poorly. Nevertheless we were quite happy with seven knots, the first ever caught on Bahia Lomas or in Chile. We were elated to finally work on birds that we have for so long only watched. We hope to accomplish a lot with these birds and the others that we catch.
First we want to know the age structure of the red knot population. We will age knots using a combination of wing feather molt sequence, coloration of wing coverts and the color of the legs. We hope to separate birds into three age classes, adult, immature and juvenile. Juveniles come to Bahia Lomas in the first November of their life and stay for two years. In their second year, they are called immature and at the end of second wintering season they will begin their 10,000 mile journey to the Arctic. The percent of each age class will help us determine the health of the population and ultimately the health of the Delaware Bay Stopover.
That night (29 January) we set up our mist nets in another attempt to capture birds. As a consequence of the low latitude the sun sets slow, twilight lasting until 11:00 p.m. We had to endure a beautiful full moon that lit a reasonably calm Bahia Lomas and the salicornia marsh. Fortunately, the night sky was partially cloudy making our mist nets a little less obvious to the birds than it would have been with a clear sky. Within a few minutes after dark we caught a red knot. Mandy and I set off to retrieve it while the rest of the team stayed at a base station where the birds would be processed. The tide reached it’s zenith just as we stepped into the gentle tidal currents. We expected the tide to fully flood the salicornia marsh so we keep everyone high. Within minutes we were catching south american terns in twos and threes and eventually we had over 61 terns, two white- rumped sandpipers, four two-banded plovers. We fully processed all birds including yellow leg bands for the terns.
Lawrence J. Niles, PhD
Chief, NJ Endangered Species Program