[Birdtalk] Godwit Migration

[John CAVITT]

Information on Bar-tailed Godwit migration for those interested - 

*--


March 29, 2007


The news yesterday morning is that the experiment of putting satellite
transmitters on Bar-tailed Godwits in New Zealand to track their
northward
migration has been a resounding success.

One bird has just reached Yalu Jiang, at the northern end of the Yellow
Sea
in China, in a non-stop flight from Miranda Nature Reserve, in the
Firth of
Thames in North Island, New Zealand. The distance between these two
locations is 9,575 km but the actual track flown by the bird was 10,200
km.
This is the longest known non-stop flight of any bird. The flight took
approximately nine days. While this bird could have chosen to stop
further
south on the tidal mudflats of China it chose to fly non-stop the
extra
distance to the northern end of the Yellow Sea to stop and feed before
its
final leg to their breeding grounds.

At least three other Bar-tailed Godwits also appear to have reached
the
Yellow Sea after non-stop flights within 6.5 - 7.5 days from New
Zealand.
Several others are still in flight and following the same track. Three
out
of 10 satellite-tagged birds which have so far migrated appear to have
stopped off on their way. One diverted westwards and has stopped in
the
Philippines, one is in Micronesia and the third has only reached Papua
New
Guinea. The New Guinea bird appeared to have changed its mind about
the
migration and has now flown south to Queensland.

These very exciting results are a reward for the perseverance and
development effort put in by the Alaskan/New Zealand team over the
last
three years. It appears they have now really developed a satellite
transmitter that is not significantly affecting the flight capabilities
of
the birds. We are now seeing a true picture of what happens during the
migration of these birds.

Only 10 to 15 years ago many people were sceptical that godwits and
knot
flew from the north west of Australia 5500 km non-stop to Chongming Dao
in
the Yangtze River Estuary. Since then it has become apparent that
Bar-tailed Godwits fly up to 11,000 km non-stop on southward migration
from
Alaska to New Zealand and Australia. It was thought this was achieved
because the birds were aided by weather conditions which gave them an
extremely strong tail wind in the early stages of that flight from
Alaska.
Researchers have now shown that Bar-tailed Godwits are capable of
flying a
similar distance on northward migration, without apparent
exceptionally
favourable wind conditions.

It has long been suspected that the very high weights reached by
Bar-tailed
Godwits, and several other species, before they leave south east
Australia
in March/April indicated the capability of the birds to reach China in
a
single non-stop flight. It would have been impossible to prove this
without
the use of satellite telemetry.

These results are a huge step forward in our understanding of the
flight
capabilities of migratory waders and therefore of the migratory
strategies
they employ. Congratulations to the whole US/NZ team on this hugely
successful exercise.

The Bar-tailed Godwits can be followed on:
www.werc.usgs.gov/sattrack/shorebirds/overall.html 


John F. Cavitt PhD, Director
Office of Undergraduate Research
Associate Professor

Mailing Address
Dept. of Zoology
Weber State University
2505 University Circle
Ogden, UT 84408-2505

(801) 626-6172
(801) 626-8541
Avian Ecology Lab 
(801) 626-8634
cell:(801) 791-4438
FAX: (801) 626-7445
homepage: http://faculty.weber.edu/jcavitt
http://departments.weber.edu/avianecologylab





"A thing is right when it tends to preserve the integrity, stability,
and
beauty of the biotic community. It is wrong when it tends otherwise."


Aldo Leopold