We have deployed 17 of the 20 geolocators. The rings fitted perfectly. Plastic ring and logger weight is 0.93 gram, the metal ring weight is 0.60 gram,
the arctic tern's weight is between 93 and 128 gram.
Some of the birds took flight immedeately, some took a minute on the ground, but at this moment all of them are taking part in reproduction again, either feeding their young or
incubating the eggs. We will monitor their behaviour in the next few days.
Catching went easy. A wire cage was enough for incubating terns. It always took less than 5 minutes before the birds returned to the nest and were caught.
After pulling the rope, the cage closed and some birds did not show any reaction before we started to move towards the cage. For terns with (moving) chicks, we used a mist net.
Arctic terns defend their nest vigorously by picking in your head or dive bombing with shit. We are usually wearing all kinds of head protection when approaching a nest.
These protections need to be soft, so the tern is not damaged when it attacks.
More on making rings,
geolocator technology, project
BIRDMAP or the
Thanks to Børge Moe, Suzanne Lubbe, James Fox and Svein Arne Hansson for their assistance. Now the biggest challenge is to find the same birds back next year and to retrieve the loggers.
Only than, we will know the migration route of the Arctic Tern between Spitsbergen and the South Pole.