Waders are declining at the Tagus estuary

Results from the long-term monitoring of wintering waders at the Tagus estuary has now brought the worrying evidence: populations are indeed declining! Wintering populations of three out of the five most abundant species, Dunlin Calidris alpina, Grey Plover Pluvialis squatarola and Redshank Tringa totanus, showed significant declines over the past three decades. In the Tagus estuary several roosts have disappeared in the last decades, while others are presently threatened by human activities, and this is likely to be one of the most relevant causes of wader declines.
This study, now published in the journal Bird Conservation International, also provides data about the phenology and patters of roost-use of waders in the Tagus estuary. New data highlights the importance of this wetland as a stopover site for waders using the East-Atlantic Flyway, with very high numbers of birds occuring during spring and autumn migration.
You can read more here.

NEW Research Grant

Job description:

Main research: foraging ecology and distribution of wintering and migratory waders at the Tagus estuary.
Tasks: capture and ringing of waders, radio-tracking work (which involves apart from radio-tracking sessions, the installation of a net of radio-tracking stations and continuous equipment monitoring), invertebrate sampling, regular bird counts at both intertidal and roosting areas.
Host institution: Museu Nacional de História Natural da Universidade de Lisboa
Grant duration: 7 months, starting on the 1st of November

Candidates should send a (max. 2 page) motivation letter and a CV (max. 3 pages, with grades) to jpgranadeiro(at)fc.ul.pt until the 22nd of October.

More informations available at http://www.eracareers.pt/opportunities/index.aspx?task=global&jobId=20031

Updating dunlin resighthings

The dunlin colour-ringing program at the Tagus estuary is still ongoing, with a total number of 430 individually colour-marked birds since last year. From our last post on this issue, we had 2 new resightings, both from Scotland.
In 2009, BO-GfG, an adult male banded at Brito saltpans (Samouco, Alcochete) in late February, was captured by Hugh Insley at the Western Isles in May. The same bird was resighted at the Tagus estuary in August.
GfW-LY, an adult bird ringed at Vasa Sacos in April 2010, was resighted in May by David Jardine off the West Coast of Scotland.
Once more we want to acknowledge the birdwatchers that have been sending information on the whereabouts of "our" dunlins.

Broadcasting live from the Tagus

Ladies and gents, the moment all have been waiting for has finally come! We have completed the first batch of radio-tagged dunlin with 19 individuals broadcasting in 19 frequencies. Just need to tune in and listen the amazing tales and stories of each dunlin.

Earlier this month the team successfully launched the “beast” (aka cross-bow net) twice over small dunlin flocks at Brito salt-pans. This marked the “beast’s premier” in 2010 and in great style too!

After the first fire, only five dunlin were caught as the flock was disturbed seconds before pressing the trigger. However, the team re-set and took position at several key points of the pan and skilfully twinkled another flock to the catching area attaining a second cohort of 9 and meeting the goal of deploying the remaining 7 radio-tags.

We are currently under intense telemetry work-load and some of us have already sold their IPods as live “DJ dunlin” broadcast is on for 24 hours! The freshly radio-tagged dunlin took the broadcasting role to their chest (well technically it’s on their back!) and are providing a great set of fixes, some of which have also been controlled for with simultaneous colour-ring reading.

Next step: hire some international dunlin DJ’s that will soon be flying in from Africa and shall broadcast the migration tales, and details!

José A. Alves

All big antennas set now

Well, today we just finished installing the last fixed (dual) antenna in the estuary, close to Alcochete. We have quite some "beeps" both at the Automatic stations (see graph below) and at the fixed antennas, and so we are starting to uncover the dunlins' secrets. We can now plot the first positions of marked birds in the estuary. It looks great, but it is a hard path, we did (and we do) step on a LOT of problems, but we are gettting better and better. Steep learning curve, this telemetry stuff...

Radio-tracking dunlins: looking forward to hear the “beep”

On the last weekend of January, at Vasa Sacos saltpans, we equipped our first dunlins with radio-transmitters. Despite the nervous and worries of a full moon night, we were able to catch 20 dunlins, and 12 of them were fitted with radio-tags, mounted and glued on their backs. A few days later we were already detecting these birds both in high-tide roosts and mudflats. Systematic telemetry sessions are now being scheduled, and we’re all the time looking forward to hear the radio-beeps … while we are not dreaming with it, it’s not worrying….

Dunlin equipped with radio-transmitter

Maria, Zé Pedro, Zé (above) and Zé Pedro, Hany, Luís (below) during a ringing session

Taking large steps for the conquest of the Tagus estuary...

It’s done! After several months of hard work (and all kind of unforeseen troubles), all the paraphernalia necessary to start radio-tracking is finally ready. We have set 9 ARTS (Automatic Radio Tracking Stations) and 3 stations with a precision directional finding antenna array. In contrast with ARTS, these last stations are manually-operated rather than collecting data automatically. These stations will be used to locate dunlins during low-tide when exploring intertidal areas, allowing the identification of the most important foraging areas.

As you can see in the map we are everywhere in the Tagus estuary… so, hopefully, no dunlins will be able to escape!!!!