Finding young spoonbills – with dataloggers

Blog by Petra de Goeij, January–February 2019

What Eurasian Spoonbills do and learn in the first years after they are born determines what routines they will have as adults. To see how they establish their habits, we give young spoonbills a GPS-tag before they leave the colony on Schiermonnikoog in The Netherlands.

The GPS-tag regularly sends SMS messages, so we generally know where the birds are, but the detailed information on location and movements that is stored in the tag can only be downloaded if a bird is close to one of our mobile antenna stations.

Since some of these young birds may never come back to the antenna stations in The Netherlands we follow them. When we know that the youngsters are “reliably” present at a wintering location we travel to this location, to download the detailed history of their wanderings and daily activities.

This trip Petra de Goeij and Arne van Eerden from the University of Groningen are targeting as much as five tagged spoonbills in Portugal and Spain. This blog gives an impression of the work. (Photos: P. de Goeij)

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Petra de Goeij and Arne van Eerden from the University of Groningen are in Portugal and Spain to find tagged young Eurasian Spoonbills. Here Arne is scanning flocks. Petra’s equipment to download the data is ready to go.
28-29 January 2019: Merida, Spain

Our first target is a young spoonbill near Merida, Spain, that was colour-banded and GPS-tagged on Schiermonnikoog in 2016. He is an almost three year old bird now, but has not been back in the colony. We notice that he has started to grow a small crest, so hopefully he will come to the Netherlands this spring.

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The first target is this young spoonbill in the middle of the flock. Near Merida, Spain

When we finally connect to the tag of spoonbill for which we traveled all the way, we see his tag has so much data that the download will take over 9 hours! Let’s see how far we get.

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The first data download of our Merida spoonbill!

While we are trying to download the data of our Merida bird, people with yellow vests appear. It turns out that a huge team of around 50 people works here every day to try to get rid of an exotic water plant. And unfortunately the last two days of our stay they are working in the favorite area of our spoonbill. Eventually, the spoonbill disappears from the reservoir. Although we do not get all data, we manage to download 5 MB from the tag. That means that we have a large chunk of its data, and we have created more space in the tag’s memory to store new data!

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This is not exactly what you think: they are targeting exotic aquatic plants that are overgrowing the reservoir

30-31 January 2019: Montijo, Tagus estuary, Portugal

After our partly successful “data grab” in Merida, Spain, we move to the Tagus estuary near Lisbon. Here we are so fortunate to get guidance from our colleague Josh Nightingale, who helps us to find our next young spoonbill near the town of Montijo. He, the spoonbill, has been sending his SMS messages from a pond behind a sewage farm. Josh speaks Portuguese and convinces a farmer that we are okay too.

Soon enough we are downloading data from this second young Spoonbill! We manage to download all his data, and looking at the data it is clear he has spent most of his time in ponds near the salt marshes of the estuary.

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A day in the rain with Josh Nightingale at the Tagus estuary (Montijo), in an area behind a sewage farm and pig farms. A special smell, but we are downloading data and of course are happy, for the moment. It cannot always be romantic…

1-2 February 2019: Evoa rice fields near Lisbon, Portugal

 Today, at the Evoa rice fields near Lisbon, the spoonbill team meets with the godwit team (Jacob de Vries and Bob Loos from Global Flyway Network). We jointly observe 450 Eurasian Spoonbills and 20,000 Black-tailed Godwits in one pond: Bob and Jacob are scanning godwit flocks for birds with rings at one side of the pond, and we are “reading” the rings of our spoonbills at the other side.

And again, we were looking for a young spoonbill with a GPS transmitter. But today no luck. About 200 spoonbills flew away when a photographer approaches them. Maybe the tagged bird was in that flock? As always, the equipment is ready-to-go to download data from the Spoonbill’s GPS tags. We wait for the spoonbills to come back…..



This research is conducted by Tamar Lok (Royal Netherlands Institute for Sea Research), Petra de Goeij (University of Groningen), and Theunis Piersma (RUG, NIOZ, Global Flyway Network).


“Guests of Summer” book of the month!

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Clipping from the British Birds e-newsletter, issue 25, 19 May 2017

Guests of Summer is British Birds’ book of the month! Theunis Piersma wrote this book about House Martins in 2014 in Frisian, and last year he translated and updated for a wider, especially British, audience.

If you are interested it is available through the publisher BTO.  Reviews by Mark Avery and Angela Turner can be found here.

Mark Avery wrote: “This is a delightful book – there ought to be more like it. It reminded me more of David Lack’s Life of the Robin than of his Swifts in a Tower, despite the obvious similarities between House Martins and Swifts, because the book is so peppered with observations of the bird that were made by chance as the author went about his daily work. And this, too, is a book written by a leading ornithologist and ecologist whose observations of the birds around him are informed by a love of birds but also an understanding of what makes them tick.”

Angela Turner wrote: “In this enjoyable book, Theunis Piersma takes time off from his well-known shorebird studies to enthuse about his other passion, the House Martin Delichon urbicum, which nests on his house in a small Frisian village.”


Update April 18 northward migration 2017: 11 Great Knots migrating; 3 already in China, 1 in Vietnam and 5 in Borneo.

By 17 April 2017 three Great Knots migrating from NW Australia have made it to China, one is in Vietnam and five are taking a break in Borneo!

On April 9 GFN researcher Ying Chi Chan (from Royal NIOZ and PhD student at the University of Groningen) photographed sat-tagged Great Knot “Green” at Guangdong coast. The bird has now carried on northwards (see green track).

Great Knot “Green” foraging at Guandong coast. @Ying Chi Chan

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Since then another Great Knot, “Red”, has arrived at Wenzhou coast.

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Note that the ongoing reclamations are made visible by the movements of the Great Knot “Red” who is following the newly build dike.

See our former blog post for more details about this coast.

A good refueling spot may be lost for both Bar-tailed Godwits and Great Knots.