Geum Estuary

Trial Site - Installed April 2019

The Geum Estuary and adjacent Janghang coast are recognised as the most important site on the Korean Peninsula for migratory waterbirds (Bamford et al 2009, Jaensch 2013, Moores 2016). It is internationally recognised as a Ramsar listed Wetland of International Importance, an EAAF Partnership Flyway Network Site and a BirdLife International Important Bird Area.

Twenty of the 39 shorebirds species regularly occurring at the Geum Estuary have been recorded in internationally important numbers (>1% of the estimated flyway population). The Geum is considered the most important site in the world for Vulnerable Eurasian Oystercatcher (Far Eastern Oystercatcher) Haematopus ostralegus osculans, supporting ≥70% of the total population. The estuary regularly supports small but significant numbers of the Critically Endangered Spoon-billed Sandpiper and the Endangered Nordman’s (Spotted) Greenshank, and is particularly notable for the large numbers of the Endangered Far Eastern Curlew and Great Knot which stopover on migration.

In addition to local large-scale reclamation, remaining roosting shorebird habitats in the area have been impacted by altered hydrology and disturbance. The lack of suitable roosting habitats in the region is seen as one of the main limiting factors to shorebird fitness.

BirdLife is working closely with Seocheon County and the Ministry of Fisheries (MOF) to conduct these trials.

This trial is funded by Woodside Energy Australia

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Wednesday August 8, “Off season”resets the bar for roost capacity. Over 500 shorebirds at Sol Ri roost!

With breeding season coming to a close, birds begin to leave the far north and filter back down the flyway. At staging areas like Seocheon County they join the skeleton crew of birds that sat out the breeding attempt. The daily movements of the tide continues and roosting sites are still at a premium.

Young-Min Moon has been monitoring the floating roosts with our remote trail cameras, swapping out the memory cards on regular visits. More recently we’ve been lucky enough to supplement our footage with that from Seocheon County’s adventitiously positioned CCTV security camera. The camera records continuously and staff members at the county’s Migratory Bird Center can even manipulate direction and zoom providing a fascinating insight into the use of the roost and the surrounding mudflats.

Shorebirds, Herons, egrets, cormorants and waterfowl regularly use the roost however it was footage from August the 6th which really demonstrated the capacity of the roost. Between 500 and 700 small waders including sandpipers and plovers were observed sitting out the high tide on the Sol Ri roost riding small ripples and jostling for position as more and more birds arrive.

Remote cameras footage has also allowed us to view the roosts’ durability during monsoon season. Oyster farmers and manufactures of the long-line oyster bags have continually reassured us of the durability and flexibility of the infrastructure even in high energy coast lines… however for those new to the concept there is always a skerrick of fear to overcome. Thanks fully we can report that despite blistering winds and wave action the roosts endured (as has been previously observed in Port Philip Bay).

  • see the impact section of the home page for more detail on the roost specs.


alternate materials investigation

With the first year of the trial coming to an end we are working on consolidating our data and reviewing results. We’re also very busy looking into traditional and emerging non-plastic materials that we may be able to utilise as an alternative to the commercially available plastic LLOB.

This study is throwing up many interesting options from a diverse array of stakeholders- from traditional Māori mutton bird storage bags and Korean diving floats to cutting-edge industrial design. Our Korean partner Ju Yung Ki (Chonbuk University) is running is investigating Korean options while we run a parallel study at this end of the flyway. We invite suggestions from all corners!

information signs

In other news the County has installed a number of snappy informative signs adjacent to the 3 roosts on the Janghang coast.


Tuesday May 27, An intended result in the intended location. Sol Ri nearly maxed out with 300 shorebirds!

Last week Dr Young Min Moon traveled back to Seocheon County to check on the roosts and swap out our remote camera cards. Since then Moon’s been glued to the screen, not watching the Game of Thrones finale or Collingwood’s stoic win over St Kilda but over 700 twenty second recordings from our roosts . There were no stories of medieval betrayal or dragons and no Brodie Grundy . .. but what was unfolding on his screen was a far more interesting tale, as enormous Yellow Sea tides marched on the banks of the Janghang coast.

In each series of clips, the monthly tide cycle progressed closer and closer to the 6.9m spring tide. With each high tide climbing higher and higher up the sea wall, existing roosts remained inundated for a longer period and more shorebirds would discoverer and descend upon our floating roost.

On May 8th around 28 shorebirds were snapped roosting on the bags at the tide’s peak but as the tide receded another 15 birds arrived to be recorded the following hour. Footage from the next day played out much the same; high tide featured 35 shorebirds propping and preening in front of the camera, with a handful more appearing to arrive as the recording faded to black. Opening the next video file Moon may have expected 50 or 60 birds but instead the roost was coated with shorebirds bobbing on the gentle swell (video below).

300 shorebirds float on the Sol Ri roost. Yes. our camera is still crooked.

Putting a lid on his excitement, Moon diligently continued the data collection and entry finding a similar pattern of peak occupancy an hour or two after the peak of the tide. Interestingly many birds even remained on the roost at low tide, a behavior we have observed at our Port Philip Bay trial.

Packaging up the footage and data for me Moon tentatively guessed there were 300 shorebirds on the roost at 6:34am on the 9th of May (three weeks after installation). Having reviewed the footage and run it through a gamut of really super impressive, cutting-edge, sciencey grid counting models (in MS Paint) i can now confirm that Moon was a bit overzealous in his estimate… in reality there was only 299* shorebirds. We will be docking his pay.

*give or take 10 birds ;)



Tuesday April 20, We’re afloat! and tenants have moved in.

During a whirlwind trip to beautiful Seocheon County we waded with 10,000 waders, combed 15 junk yards for engineering solutions, ate 18 types of Kim Chi and ultimately installed 3 new floating roosts. Before we could even exit the water birds where investigating our new real estate options and by day 5 colonisation had begun with a number of waterbird species observed including nocturnal roosting Grey Heron, preening Cormorants and as many as 15 shorebirds of various species in a single sitting.

Read on to hear more about the trip.



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Open for inpection

Terek Sandpipers were the first to trial the roost

consultation

For the last 9 months our man on the ground, Dr Young-Min Moon (Moon to his buddies), has been busier than a one-armed plastic surgeon in Gangnam, preparing for our Korean floating roost installation. In order to have the roosts ready for the swell of shorebirds arriving on northern migration, Moon and partners at Seocheon County conducted consultative workshops with land managers and NGOs in Incheon and with local fishing communities in Seocheon. The Ministry of Oceans and Fisheries delivered the final stamp of approval 2 days before our proposed install date, so Kangaroo Island oyster farmer, Bob Nichols and I packed our mud gear and jumped a plane for Korea.

Upon arrival in Seocheon County we were greeted by a very supportive, enthusiastic and athletic team of county officials and Migratory Bird Centre staff.

Our team and 360 Zapco oyster bags made the trip from the south of the county to Seoin-ro in the north where our bounty of oyster shell awaited. Over a century ago the first bible arrived in Korea at Seoin-ro and by the looks on the faces of the local fisherman we were introducing something just as bizarre.

Utilising the aforementioned enthusiasm and athleticism we filled the bags and ferried them to the install sites in Jangu Bay and Sol Ri. Our mode of transport couldn’t have been more Korean - the KIA BONGO III is sturdy, compact and efficient. Although authentic, the Bongo may not have been the right scale for the job, taking 3 trucks 3 cross-county trips to to complete the task… not that we were complaining as we got to enjoy the serene Seocheon countryside which was blushing with iconic spring blossom.

Construction

Tens of thousand of shorebirds circle over the Janghang Coast at high tide as we install floating roosts

The mud on site was a dream to work in- hard enough to walk across, yet soft enough to drive our anchors into. Bob’s customised ratchet arrangement along with some kim-chi fueled muscle power made short work of most of the anchor installation. When the going got tough we jerry-rigged an oxen mill - subbing in Dr Moon for the ox.

As we toiled throughout the rising tide, tens of thousands of shorebirds arrived from adjacent areas, already inundated by water. Vying for roosting position they pushed with the waters edge ever closer to us… and beyond us the inevitable seawall that would push them into the sky once more.

With the anchors in, all that remained to do was to clip the bags to the lines on shore and wait for a sympathetic tide that would allow us to tow them to their final destination. However, on a coastline where seawalls replace gentle, sloping dunes or embankments, transferring the bags from the road to the tidal flat proved a challenge. Luckily the Yellow Sea provided enough flotsam building materials to construct a makeshift slide which traversed the 3m wall. Bags sailed down the wall where they were clipped to the stormline.

Unlike the configuration of the Australian trial (or indeed commercial oyster operations) we arranged the ROK bags as close as we could without compromising the flexibility of the structure. This new configuration will hopefully improve thermoregulation of roosting birds by allowing them to roost in large numbers in closer quarters.

Once the racing tide reached us, the bags were floated and towed into position. As we secured the lines to the anchors an aerial roost of over 15,000 desperate birds swarmed above our heads. Small, vocal fragments broke off the various flocks, swooping down to investigate potential roosting areas only to be turned away, dissapointed.

colonisation

Upon tying off the final buoy, Bob scaled the seawall to join the rest of the team surveying the day’s work. With Bob high and dry 6 Terek Sandpiper swooped in, hovering over the roost. Several tentatively dangled their landing gears as if testing our craftsmanship before taking off, circled once more only to return and land on the newly finished roost. Two birds enjoyed the roost so much they remained there even once the tide had receded!

The roosts are now being monitored by staff from Seocheon’s Migratory Bird Centre using remote cameras. In the first week after installation the cameras recorded initial colonisiation. A number of waterbird species have been observed including noctural roosting Grey Heron, Great Egret and shorebirds. By day 5 at least 15 shorebirds were using the Sol-Ri roost, most likely Bar-tailed Godwit, Terek Sandpiper and Grey-tailed Tattler.

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tell your friends

A mixed flock of >15 waders checked in on day 5. As northern migration continues species arrive and leave asynchronously. Who will drop by next?


Chris Purnell