Shorebirds Report
April 2007
They made it!
As reported last month, Bar-tailed Godwits were fitted with tiny satellite transmitters to track their northward migration from New Zealand to the northern hemisphere. Most of the transmitters seem to have worked well and some of the birds are already resting and feeding in the Yellow Sea Area of China. They have flown over 10,000 kilometres without stopping and have done it in just over a week!
The scientists who have been conducting the research have also done a great job in reporting the northward migration on the web page: http://www.werc.usgs.gov/sattrack/shorebirds/overall.htm
Each transmitter was set to report every second day and plotting these on a Google Earth map showed the distance travelled since the last transmission and the average speed over that time for all the birds. The birds travelled at speeds of up to 60 kilometres an hour and covered between 2000-2,500 kilometres every couple of days. An amazing feat!
The migrating birds have also set several unanswered puzzles. One bird flew as far as New Guinea and then turned back and is presently in North Queensland. Another has stopped off in the Philippines and still another has stopped on an atoll in Micronesia.
Godwits around our own bay do not all leave at the same time. Over several weeks we see a change in numbers until only over-wintering birds are left. One of the satellite tagged birds in New Zealand has left nearly two weeks after the others but has already nearly reached Japan.
Bar-tailed Godwits from our own bay waters are travelling the same route and the same distances. They can only do this because of the rest and food they get here over the summer. If the bay waters were ever to change and the amount of small marine creatures to decrease then the birds would no longer be able to use this area as a summer roosting area. If there is too much disturbance when the birds are roosting they also have difficulty in increasing their body weight to the level that enables them to make the long migration. Our bay is a great place and we need to keep it that way!
Other migratory waders that spend the summer here also fly similar long distances to reach the northern breeding places. The difference is that they make a similar journey by flying smaller distances and stopping off at a number of places on the flyway to rest and eat.
The count this month was interrupted because the chief counter was sick.