Jeroen Reneerkens

Missed our conference, or just want to see more amazing #wader #shorebird research?

Members can check out the early online #WaderStudy journal here ⬇️
www.waderstudygroup.org/publications... #ornithology

What happens when the mud disappears? The Yellow Sea provides important ‘service stations’ for shorebirds on the East Asian-Australasian Flyway, especially on their way north to Russian and Alaskan breeding areas. In a thought-provokin…

What happens to shorebirds when the mud disappears?
wadertales.wordpress.com/2022/10/15/w...
Blog from 15 Oct 2022 🎂3️⃣
#ornithology

Reminder!
@jeroen-reneerkens.bsky.social appreciates reports of colour-ringed Sanderlings:
submit.cr-birding.org/projects/181/
Counts of adult/juvenile Sanderlings in flocks are great too.
Blog about the Greenland Sanderling project:
wadertales.wordpress.com/2019/10/04/t...
📷 @markaeaton.bsky.social

Thank you to all of today's speakers for a really interesting array of talks! So much great research, and more on the way tomorrow! #IWSG2025 #waders #shorebirds #ornithology

The colour-marked Sanderling photographed in Israel, still carrying its radiotransmitter

A vagrant juvenile Sanderling turned up in Israel—likely after a single non-stop flight from the Dutch Wadden Sea. Here’s thread explaining why that’s remarkable and interesting. @wadertales.bsky.social @globalflyway.bsky.social #Birds #Migration

Thanks to the Israel Bird Ringing Center for the report, Katya Rudnev for photos, and colleagues at @niozsearesearch.bsky.social for long-term ringing and tracking and to @natuurmonumenten.bsky.social for permission to perform our research on Griend.

If you observe a colour-ringed Sanderling, please report it here (photos help!): submit.cr-birding.org/projects/181/

Reports are useful for studies of migration routes and survival. I am also interested in counts of adults and juveniles within flocks #CitizenScience

Will the bird stay in Israel this winter, or continue to the East African coast (where many Siberian-origin Sanderlings likely winter)? We’re watching closely. #AfricanEurasianFlyway

Are Sanderlings seen in Israel usually Greenlandic, or could this be Siberian origin? Was this juvenile born in Greenland—or farther east?

Questions: Why the route change? Was this bird travelling alone (no experienced guides)? How often do juvenile Sanderlings push inland routes across Europe?

Map of Europe–Africa showing Wadden Sea colour-ringed Sanderling sightings; larger dots = more birds; Israel marked and linked to capture site with dotted line.

Map shows all out-of-Netherlands sightings of Wadden Sea colour-ringed Sanderlings (locations within 5 km merged; dot size = number of birds). The Israel point stands out clearly as an outlier.

Reported in Israel, ~3,200 km from the Wadden Sea. Given timing and track, a non-stop flight across much of Europe is likely. Photo credit: Katya Rudnev via the Israel Bird Ringing Center. @shai-blitzblau.bsky.social #Israel #Birding

16 Sept (midday): Tracking shows the bird using mudflats near Griend, then moving SW, leaving the Wadden Sea in the SW corner—before turning SE. A sharp course change away from the coast. #Migration

This juvenile was caught and colour-ringed on 27 Aug 2025 near Griend (Dutch Wadden Sea). A WATLAS transmitter was fitted to track fine-scale movements locally. @allertbijleveld.bsky.social @niozsearesearch.bsky.social #WaddenSea #Tracking

Low fitness at low latitudes: Wintering in the tropics increases migratory delays and mortality rates in an Arctic breeding shorebird This study describes three fitness correlates over a sixfold range in the lengths of annual return flights (3,700–22,200 km) in a small migratory shorebird. Low survival and delayed migration in the ...

Choice of a non-breeding site matters! Survival and timing of migration vary by non-breeding location. Our study: besjournals.onlinelibrary.wiley.com/doi/full/10....
#Ecology

Sanderlings pick their non-breeding site on their very first southward trip, at ~2 months old. They usually return there every year—just like they are faithful to a breeding area. Such early choices shape a lifetime of migration routes and conditions. #Shorebirds

The colour-marked Sanderling photographed in Israel, still carrying its radiotransmitter

A vagrant juvenile Sanderling turned up in Israel—likely after a single non-stop flight from the Dutch Wadden Sea. Here’s thread explaining why that’s remarkable and interesting. @wadertales.bsky.social @globalflyway.bsky.social #Birds #Migration

Colour-ring readers jave contributed greatly to the science underpinning 1️⃣0️⃣ years of WaderTales blogs.
One of the best studies, in terms of feedback to observers, is the Sanderling project run by @jeroen-reneerkens.bsky.social.
More here:
wadertales.wordpress.com/2019/10/04/t...
#ornithology

This month, WaderTales will be ten years old.
I'm going to create a thread that highlights some of the research findings that have surprised me.
Plenty of "Wow!" & "I didn't know that!" moments.
Here's a link to the catalogue of 150 blogs
wadertales.wordpress.com/about/
#ornithology

It is juvenile #Sanderling time!

Observers, please share your counts of adults and juveniles with me (j.reneerkens@ecos.au.dk; do not use the address in ageing guide!). I will use them in population models to.

📄 Find the ageing guide here: bit.ly/3HQdb5M

Sanderling.
Just a few weeks old.
Imagine arriving in St Andrews, from Greenland.
Should you stay?
Or fly to England, Portugal, Mauritania or Namibia?
Where's best?
If only this bird could read:
wadertales.wordpress.com/2019/10/04/t...
#ornithology @jeroen-reneerkens.bsky.social

It is juvenile #Sanderling time!

I am very interested in counts of adults and juveniles to be used for population models. Please use the manual and send your counts to j.reneerkens@ecos.au.dk (not to address in ageing guide!).

📄 Download ageing guide: bit.ly/3HQdb5M

Silver Lining for Shorebirds: New Study Shows Arctic Nesting Species Are Cued into Climate Change Attentive long-distance migrants are following environmental cues better than expected, showing some shorebirds to be surprisingly adaptable.

I recommend the well-illustrated blog post by Alaska Audubon on our recent paper in Global Change Biology led by Eveling Tavera Fernandez and Kirsty Gurney about the effects of climatic variation on timing of nesting in arctic shorebirds.

ak.audubon.org/news/arctic-...

@alexanderlees.bsky.social Not necessarily so! This is just my experience from one location in a large NE Greenland. Colleagues elsewhere in NE Greenland are experiencing a lemming peak year with many snowy owls and great nest survival of shorebirds, as we experienced last year in Zackenberg.

Arctic fox

Certainly, I had just ringed them. I expected the parent to walk away with the chicks.

Yes, that communication between adult and chicks sounds great, right?

Shorebird chicks are hatching here in Greenland!

This year, egg predation has been intense, especially on Turnstone clutches, so every successful hatch feels extra special. This Turnstone male brooded its four chicks right next to my phone. A bit too close maybe...

@chorlnev.bsky.social I have thought the same and it could be the reason. However, I had the impression that the female didn't intend to leave until he started pecking at her.

#sanderling copulation is a balance act. It always ends with the male fiercely pecking the neck feathers of the female. I have no clue why.