Holder of the record for the longest non-stop migration in the world, the mysteries of this extraordinary bird are gradually being solved with use of some of the lightest satellite tags yet developed. World On The Move will be following tagged individuals on their northward migration.
From New Zealand to Alaska via the Yellow Sea in the spring. From Alaska to New Zealand non-stop in the autumn.
Time and Distance
A round trip of some 25,000 km with the return leg coming in at 11,500 km non-stop in 8 days.
The birds go on a binge, a feeding frenzy, before their long haul flights until up to 55 per cent of their weight is fat. They then reduce the size of their gut, kidney and liver by up to 25 per cent to compensate for the added weight. Obese with fuel, freed from the baggage of a heavy gut, the Godwits are ready for the air. The scientists think that the birds reshuffle proteins in their bodies before they set out and that this allows them to reduce the size of their food-processing organs.
Reason for Migration
In search of the best feeding grounds. There is very little appropriate habitat for them between the extreme ends of the migration.
70-100,000 Bar-tailed Godwits breed across western Alaska, making the entire population vulnerable. Their northbound migration stopover sites in Asia face some of the heaviest reclamation pressure in the world.
What happened in 2008?
The Pacific Shorebird Migration Project tagged 9 Godwits in New Zealand in March and were able to track them until October when the batteries in their transmitters ran out. The northward journey of the Bar-tailed Godwits began in mid-March and included a several-weeks-long stopover at coastal sites in China and Korea on the Yellow Sea. Unfortunately, we weren't able to follow all the tagged individuals as a few of them didn't complete the arduous migration and some of the transmitters failed.
Nevertheless, at the end of May we discovered that 2 male Godwits had reached their breeding grounds on the Yukon Delta in Alaska where they spent most of June and July. They were there to mate but from the data collected it seems only one of the males was successful.
We were hoping that we would be able to follow their southward migration back to New Zealand in order to reveal whether these Godwits would also complete the longest non-stop flight of some 11,500 km but sadly the batteries in their transmitters died on us. However by October those tagged Godwits had been spotted back in Miranda, New Zealand.