Twinkling the Whimbrels
By Nate Senner, Ph.D. candidate
December 16, 2008
If At First You Don’t Succeed…
After a few days of leisurely driving around Isla Chiloé looking for color-banded Hudsonian Godwits and Whimbrels, it’s time to put the expedition into high gear. We’re here to catch and band birds, and for that we need an elaborate system called a cannon net, run by our team’s two cannon-net experts, Larry Niles of the Conserve Wildlife Foundation and Humphrey Sitters of the Wader Study Group.
As odd as it may sound to use cannons to catch birds, they’ve been instrumental in shorebird conservation over the past couple of decades, allowing us to catch lots of birds (up to 400) at once. But how do you catch birds with cannons?
Well, very carefully would be my first answer. There’s always some danger involved for the birds. We take the risks because of the immense amount we can learn from knowing exactly where banded birds go and how long they live – and we do everything in our power to safeguard the birds. In our two-year project we’ve never had a single injured or killed bird.
Cannon netting consists of firing three projectiles over a flock of birds, trailing a single net that traps the birds underneath. Setting up the cannons is a daylong process that involves digging three separate metal tubes into the ground about 15 or so feet apart and stuffing them with a long, metal projectile, each of which will carry one section of the long nylon net.
When the tubes are dug in and properly aimed, we hook each cannon into an electrical system and place black powder at the base of the cannons. Then we string a set of wires back to a control box strategically placed a couple of hundred feet away in a well-hidden vantage point. After all of that is in place, we dig a trench to conceal the net and cover it with seaweed and other detritus. Then it’s a matter of hiding and waiting for the birds to arrive. Just imagine Wile E. Coyote trying to catch Roadrunner with a big contraption triggered by TNT in the old Looney Tunes cartoons. We’re not quite as angry or ineffectual, but we’re still using explosive-laden cannons to capture some wary prey.
The next day, it was clear from the start that nothing would go exactly according to plan. Our goal was to catch a lot of Whimbrels, but at first the entire bay’s only flock was roosting contentedly a couple of hundred yards from our net – far out of range. So while the rest of the team hid, Brad Andres of the U.S. Fish and Wildlife Service had to wander out onto the flats, trying to look as harmless as possible, while still twinkling, or slowly pushing the birds toward our net area (In case you are wondering, the word twinkling was thought up by the Australian guru of cannon netting, Clive Minton). Very slowly this began to work and the Whimbrels in groups of threes and fours picked up and flew over to in front of the net.
But soon a new problem arose. A Southern Lapwing decided to fall asleep right in front of the net, smack in the middle of the danger zone. That’s the area just a few meters from the front of the net. Any bird standing there when the net is triggered will have a high likelihood of getting either killed or gravely injured. Whenever we catch birds we have to constantly monitor to make sure no birds are in this area. Having one bird in there from the get-go made us all a bit nervous. Would more birds move into the danger zone to join the lapwing?
As the tide rose, more and more Whimbrels moved into the capture zone, but the lapwing stayed put. Then, all of a sudden, half of the Whimbrels took off for the far point of the bay, taking the lapwing with them. One of our problems was solved, but our potential catch was cut significantly, as only 80-100 birds remained.
All we could do was wait. After another 45 minutes, the advancing tide had finally pushed 80 Whimbrels into the catch area. Gauging the small possibility that the rest of the flock could be induced to enter the capture area, we decided it was now or never. So with a 3-2-1 countdown, Larry gave the signal to fire the cannons and…nothing happened! The nets did not fire.
We needed to take drastic measures. Humphrey, who was closest to the net, had to head out onto the flats and do something we would never otherwise do: twinkle the birds away from the net. We all cringed as the flock scattered in front of Humphrey. Fortunately, though, they only moved about 60 yards down the beach instead of off to another bay. Then Humphrey inspected the cannons and quickly found our problem – one of the wires leading to the back of the third cannon was loose, ruining the connectivity of the entire system like a string of Christmas lights with a broken bulb. After tightening the wires, Humphrey then had to twinkle the birds back into the catch zone. Here, finally, luck was on our side, and the flock moved right back into place.
With some 60 Whimbrels in the capture zone, Larry again gave the signal, and this time, Kaboom! We all made a mad dash to the net to secure everything and make sure no Whimbrels had been hurt (none had). Quickly we moved all the birds out from under the net and into some roomy keeping cages covered with black cloth to calm the birds. Then we were able to sit down and band our catch: 56 Whimbrels. Given the circumstances, a catch we were very happy with.
We had met our expedition’s minimum goal for Whimbrel catches, so our next step is to capture a large number of Hudsonian Godwits at Bahía Pullao, just a few miles from Castro and chock full of godwits, whimbrels, and gulls. Last year we were able to catch nearly 200 godwits there during our expedition.
I’m hoping that catch will go a bit more smoothly and perhaps in my next post I’ll be able to report that we’ve caught some godwits as well!