Shorebirds Report
March 2007
Shorebird Migration
We live in a great part of the country! It would be almost perfect – except for the insects that make part of the year unpleasant. It is hard to imagine anyone – or anything – wanting more insects! But that is just what sends the migratory wader birds off to the far north of the world for the northern summer.
Right now the places where the birds spend the northern summer are covered with snow and ice and the temperatures are well below zero. Some of the birds are so anxious to get there that they will even arrive before the snow has fully gone. As the temperature starts to rise the whole area comes to life very quickly. Spring flowers and grass shoots push through patches of snow and by the time it warms up a little more there are swarms, and hordes, and millions of insects! This is exactly what the migratory wader birds need to successfully raise a nest full of babies!
Migratory waders around our bay are all getting ready to fly north. Over the last month or so many have been changing into breeding plumage. This plumage may be more patterned, or darker, or in some cases an entirely different colour. One of the most dramatic changes is seen in the Bar-tailed Godwit. For most of the summer these birds are a grey-brown colour above with a barred whitish rump and tail, but in breeding plumage the head, neck and underparts become a bright chestnut. The colour change is spectacular!
The Bar-tailed Godwit (Limosa lapponica baueri) that migrate to eastern Australia also goes to New Zealand. It makes the longest non-stop migration of any bird – over 9,700 kilometres. This is an unbelievable distance! During the last two southward migrations Bar-tailed Godwits have been fitted with satellite transmitters and researchers have tracked this long flight. They have found that the birds make use of favourable weather systems and use tail winds to boost their flight speed. Not very much is known about the northward migration. However, it is thought that the birds take a different route – up the East Asian Australasian Flyway.
In February of this year a number of birds were again fitted with satellite transmitters and it is hoped that this time we will learn where the birds fly on the northern migration. The following web site is giving regular updates: http://www.werc.usgs.gov/sattrack/shorebirds/overall.html
This last month we counted 31 species and 1030 birds.