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Chris Hassell from the Global Flyways Network begun in 2006 explains how it came into operation and why it is important for research into migratory shorebirds. The Global Flyways Network is a very large group of researchers under one umbrella, Chris Hassell being its only employee. The researchers he works with are already in formal tertiary institutions Theunis Piersma Nederlands University Nederlands Institute for Sea Research. The Global Flyways Network was begun by Theunis Piersma and Dr Alan Baker from the Ontario Museum, both of whom felt the need for a very broad collaboration of scientists looking at migratory birds across the globe. Given that there are seven global flyways for migratory birds, the collaboration was seen as a way of spreading the known science about migratory birds, a goal which is being achieved.
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| Bohai Bay salt pond. Image by Adrian Boyle.
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One of the most important advances for the network has been satellite tagging. Originally designed for whales and then adapted for turtles, it can now be used for the smaller migratory shorebirds. It is exceedingly expensive but the data that is produced gives enormous insights into their migratory patterns. Such tags can not only locate where the birds rest on their flights but also track how far they are flying and how fast, all of which can be correlated with variables like prevailing weather conditions at the time. Advances in tagging technology have meant that smaller shorebirds, like Red knots, can now be tagged just like larger ones, such as the Bar-tailed godwits, research currently being tested at the Neos Institute in The Netherlands. The tags are implanted on the birds as a leg harness or a a wing harness and the only limiting factor on data provided is the battery life of each implanted tag which these days are solar powered. The tags are programmed to suit each particular data project, so the data collection for shorebird foraging at Roebuck Bay is different to the data programming for a shorebird species migratory flight. In America such data harnesses have been tracking shorebirds for four years, proof of their longevity.
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| Theunis Piersma and Chris Hassell, Bohai Bay. Image by Adrian Boyle.
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The effect of climate change is not yet known for migratory shorebirds but given that they have managed to adapt to four billion years of the earth’s evolution there is hope that they can still adapt to further changes, provided they have the timescale of generations to do so. Chris Hassell predicts that migratory will adapt to changing habitat circumstances by changing their northern migratory flights to include places like The Philippines, instead of flying straight for the Yellow Sea which is rapidly losing its shorebird mudflats. For Red knots, however, their specialist feeding habits rely on bivalves of a certain size, which only occur in intertidal mudflats, so they cannot readily adapt to other food sources like crabs and worms, although they have been seen feeding on brine shrimp in the Yellow Sea salt ponds which replaced the mudflats. Indeed, on one day in late May this year there were 34,300 Red knots feeding in one single salt pond and given that 116 were tagged from Broome, Chris Hassell estimates that over 90% of the Piersmai species of Red knots was in that one Yellow Sea salt pond which had an abundance of the bivalves.
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| Chris Hassell and Adrian Boyle on salt pan. Image by M Slaymaker.
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The salt ponds are increasingly becoming the stopover point for over 50% of migratory birds, given that the mudflats are diminishing, so the Global Flyway Network is increasing its data gathering there. One salt pond, some 3km², had 95,000 birds, 60% of which were Curly sandpipers whereas once they would have all fed on the mudflats. This is not always the case as the salt pond themselves are subject to changes but it is true that many migratory birds are using this new habitat as their migratory stopover. There has been a recent slowing in the redevelopment of the Chinese mudflats, with less building of sea walls and less pumping, although they are building on the reclaimed areas. Disturbingly, there is a newly constructed six lane highway that stops at the sea wall, a harbinger of further development which is mirrored up the coast to the Korean border with new roads and billion dollar port facilities on scales that reflect the Chinese used of imported raw materials. Up for question is whether such Chinese development will be a turning point, tipping the scales against migratory birds.
Chris Hassell was interviewed for A Question of Balance by Ruby Vincent. Images provided by Chris Hassell. Summary text by Victor Barry, July 2013.
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| Chris Hassell, Bohai Bay mudflats. Image by Adrian Boyle.
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From the Archives.....early days for the GFN with Chris Hassell
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Chris Hassell, based at Roebuck Bay WA, and Research Coordinator from the Global Flyway Network, gives us the inside information on an international shorebird research project that focuses on migration and survival of individual shorebirds, as well as overall populations. He is specifically looking at the global flyway that stretches from Roebuck Bay in Western Australia to the Yellow Sea and to the Arctic. Other researchers are investigating other global flyways. It is a worldwide collaborative project involving several countries and using the latest banding technology to track the birds. The project will provide detailed demographic information on a range of shorebirds.
Tagging birds is not new. It has been used since the early 80s and in the early 90s tagging was used as a way to see the birds from a distance (using different coloured flags). This type of tagging has allowed researchers to know the country of origin of birds and to observe birds in the wild without having to recapture them. We now know that some birds live for up to 21 years.
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Right: Chris and his team use canon nets as a safe and effective way to capture a large number of birds at one time. This method is suitable for use on the beach when large flocks of birds are roosting.
Photo by Andrea Spencer
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| Left: The unique combination of coloured bands assigned to individual birds means that they can easily be identified at a distance.
This makes it possible to collect far more information rapidly and simply and with minimal distress or disturbance to the shorebirds.
Photo by Adrian Boyle.
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| Right: A Great Knot photographed on mudflats on the Yellow Sea in China by Chris Hassell.
From the coloured bands on the bird's legs, Chris was able to identify it as one that he had banded back at Roebuck Bay in Western Australia.
Blood samples are taken from the birds at their inital capture so that detailed information can be collated and interpreted in relation to determining which variables are important in aiding (or hindering) survival.
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Do male shorebirds live longer?
Are particular roosting places a help or a hindrance?
These tagging expeditions will allow researchers to finally capture the individual life history of a range of birds.
Given that the worldwide population of shorebirds is in decline, this information should be particularly useful in understanding the ecology of bird species.
That’s for sure.
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| Left - Roebuck Bay at low tide revealing the mudflats that team with life and food for the shorebirds.
Below - with the return of the tide, the bay looks like any other beach except for the unusual red Pindan sands. Photos by Paul McQueen
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Chris Hassell was interviewed for A Question of Balance by Ruby Vincent.
Summary text by Victor Barry, August 2007.
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