Bart Hoekstra

Schrijver Jac. P. Thijsse telde ooit duizenden vinken langs deze laan. Waar zijn ze nu? Natuurhistorie: Een eeuw geleden was een van de mooiste lanen van Nederland een trekpleister voor vinken en kepen. De laan is nog steeds mooi, maar de meeste vogels zijn verdwenen. Ligt het aan de beu...

Schrijver Jac. P. Thijsse telde ooit duizenden vinken langs deze laan. Waar zijn ze nu?

Leuk artikel van Addie Schulte in @nrc.nl.
www.nrc.nl/nieuws/2025/...

This paper is very much a shared achievement, made possible by our “radar group” and close collaborators: Bart Kranstauber, Maja Bradarić, Johannes De Groeve, Stacy Shinneman, Berend Wijers, Hidde Leijnse, @hansvangasteren.bsky.social, Adriaan Dokter, Emiel van Loon and @judyshamounb.bsky.social.

Fig. 2. Maps of nocturnal bird migration across the Netherlands in spring and autumn, with the 100 km radius circles of the weather radars enclosing the onshore study area. Colors represent seasonal migration passage, converted from the original bird densities. Shaded areas mark grid cells for which over 25% of the input data, prior to filtering, were impacted by ground clutter. Migration passage in these regions may be compromised in either direction: overestimated due to remaining clutter artifacts or underestimated where terrain features partially obstruct the radar’s lower scanning angles.

Fig. 1. Flight altitude distributions (in m above sea level (asl)) of nocturnal bird migration for both Dutch weather radars at a coastal Den Helder and inland site Herwijnen. Bar length denotes the proportion of migration within the respective altitude range (50 m vertical resolution). Donut charts aggregate this further to coarser 200-m classes and display the proportion of migration occurring above 1000 m (patterned). Red highlights indicate the altitude range of onshore energy infrastructure in the Netherlands, which is generally present in the lowest 200 m of the atmosphere. Donut chart proportions do not sum to 100% due to rounding. The small inset map of the Netherlands shows the locations of both radars (solid dots) and the surrounding areas up to 35 km (circles) from which altitude distributions are aggregated.

Fig. 3. a, c Observed combinations of migration passage and mean wind power density, a measure of wind power potential, in North-Holland. Red circles represent average values for candidate sites and their size reflects the relative candidate site area. The grid reflects binned values of migration and wind power density, with color shading indicating the type of combination: orange = high migration passage, blue = high wind power density, dark browns and blues = both high. White lines indicate averages for wind power density and seasonal migration passage. b Spatial distribution of autumn migration (orange hues) and wind energy (blue hues) in North-Holland. Candidate wind energy sites are shown in bright red. The highest and lowest autumn migration passage sites are linked to their positions in a and c, emphasizing large differences between sites in autumn, but not in spring. Shaded areas mark grid cells for which over 25% of the input data, prior to filtering, were impacted by ground clutter. Migration passage in these regions may be compromised in either direction: overestimated due to remaining clutter artifacts or underestimated where terrain features partially obstruct the radar’s lower scanning angles.

To reduce negative impacts of #renewables (eg #windenergy) on migrating birds, we need to know *where* and how *high* they fly. Using weather radar, we mapped 6yrs of nocturnal migration over the Netherlands, revealing patterns we can use to avoid and minimize impacts:

doi.org/10.1016/j.je... 🧪🪶

Yup, far from a solved issue somehow. My gut feeling is that it's worse (for me) further back in the plane, where engine noise is more prominent, but I don't fly often enough to have tested that properly

I’ve had this issue for years in the AirPods Pro 2s, but not in all flights/seat configurations. Haven’t narrowed down precisely, but cabin hum frequency probably plays a role. Luckily I also have the old Pro 1s, which are flawless during flights.

Dispersal, maturation and recruitment in a long-lived, intercontinental migrant bird | www.sciencedirect.co... | Animal Behaviour | #ornithology 🪶

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Opinion piece on needs and why to improve on subseasonal-2-seasonal modeling i.e. the forecasting range that is in between short-term forecast (e.g local weather next week) and the seasonal ("will this winter be wet?").

This photo accompanying a news story about the heist at the Louvre is perfection.

This graph says it all: instead of starting to go down, the *annual increase* of atmospheric CO2 is setting new records. We're making climate change worse at a record rate.
Turning this around should be our top priority, and it's not.
From: www.carbonbrief.org/met-office-a...

"Charismatic species increased negative workplace experiences..."

No freakin' kidding.

Link: besjournals.onlinelibrary.wiley.com/doi/10.1002/...

Link doesn't work..?

Well, it's official. After our paper last year (onlinelibrary.wiley.com/doi/full/10....), the Slender-billed Curlew is officially declared Extinct today.

Scientists dream of describing new species, not writing their obituary and epitaph, knowing that they are gone forever #ornithology

170K raptors! 🤯

8 yrs in the making, but I’ve finally witnessed a 100k+ raptors day while on the station actually counting the bulk of it. Incredible experience. Still feeling cross-eyed from staring through the scope non-stop for almost 10hrs.

📸: the Shuamta team at the end of this incredible day

Some rare and remarkable processes are taking place this week, that we are not likely to observe for a long time!
These 2 Atlantic hurricanes are closer than any since at least the 1960s. They are now connected - in each other’s orbit, pivoting. Follow along 1/

Our research makes it clear: by capitulating to the right, Labour is driving voters to Reform UK | Tarik Abou-Chadi and Stuart Turnbull-Dugarte Mimicking Farage on immigration is senseless. Labour voters feel betrayed; anti-immigration voters see through the ruse, say academics Tarik Abou-Chadi and Stuart Turnbull-Dugarte

"We studied more than 70 different elections that took place in 12 western European countries over several decades, and found that when mainstream parties take more anti-immigration positions, it leads to more support for the radical right, not less."

Let's All Remember When We Saved The World To remind ourselves we can do it again.

I honestly don't think everyone talks enough about how amazing it was when the world came together to fix the hole in the ozone layer, so I wrote this:

everythingisamazing.substack.com/p/lets-all-r...

It's a good reminder of what we're capable of.

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

Animal niches in the airspace For flying animals, including many birds, bats, and insects, the air is a crucial arena for a range of behaviors. Technological advances, such as year-round tracking of flight altitudes and expanded u...

Are animals randomly distributed in the air, or is there a structure to where and when we find them? In our new paper we outline factors that shape habitat use in the air, from abiotic structure to biotic interactions. A lot of fun discussions behind this one! 🦅🦋🦇🌬
www.cell.com/trends/ecolo...

YouTube video by The Daily Show Jon Stewart's Post-Kimmel Primer on Free Speech in the Glorious Trump Era | The Daily Show

Jon Stewart's Post-Kimmel Primer on Free Speech in the Glorious Trump Era

youtu.be/_GXNJ3V9lzg

One of many kettles of Black Kites we've counted over the past days. Photo by Sander Bruylants.

A crisp juvenile Lesser Spotted Eagle in beautiful light. Photo by Sander Bruylants.

Screenshot of our live seasonal raptor 'counter' on the website.

ONE MILLION RAPTORS!

The wait is over... Today #BRC17 hit the earliest 1-million mark in BRC history! Usually, this happens around end-September, but this year the raptors clearly had other plans.

And with still over a month to go, we expect plenty more to come!

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#ornithology #RaptorResearch

One of the best talks I’ve seen this CWW — and that’s coming from a bird guy

A good day to read about #aeroecology—and to appreciate the work being done by the good people at @nycbirdalliance.org and @cornellbirds.bsky.social to protect migratory birds. The #TributeinLight monitoring they do is so important (and respectful). 🌎 🐦 #ornithology #conservation

One million raptors: But where do they come from? — Batumi Raptor Count As a migration counter, you can’t help but wonder: “Where did the bird I just tallied come from, and where is it going?” In light of BRC’s main aim — monitoring raptor population trends — this very ...

A new study led by @moveandconserve.bsky.social used GPS tracking to test the monitoring potential of Eilat and Batumi.

An invaluable step toward linking counted birds to their origins, but we found it needed some elaboration from a migration count perspective!

Our commentary: tinyurl.com/nnbzu7kc

A slippery slope if you think about khachapuri every time you go through your office door 😬😅

The results are very much a shared achievement, made possible by our “radar group” and close collaborators: Bart Kranstauber, Maja Bradarić, Johannes De Groeve, Stacy Shinneman, Berend Wijers, Hidde Leijnse, @hansvangasteren.bsky.social, Adriaan Dokter, Emiel van Loon and @judyshamounb.bsky.social

The opening slide of the presentation titled ‘Large-scale radar-based mapping of nocturnal bird migration for avoidance and minimisation of wind energy impacts’.

Tomorrow at #CWW2025 I’ll present new work on using weather radars (the ones you check for 🌧️) to map nocturnal bird migration to support wind energy planning.

Join my talk at 11:30 (Auditorium Pasteur) to see how this can improve impact assessments and enable a more nature-inclusive energy future.

Some asked if we had a ‘beef’ with Efrat et al. — quite the contrary! Their elegant work merited a proper response, so we wrote a letter to share our view on their work and long-standing Qs about migration counts.

If the khachapuri doesn't get to us first, we still fit together through one door! 😁

Using GPS tracking data to validate the conservation value of bird migration counts Effective conservation of migratory birds requires gathering of information about their population trends, often acquired using migratory bird counts.…

Science as a conversation:

In January, we published a paper about migratory bird counts www.sciencedirect.com/science/arti...

For different reasons, we did not include the managers of the bird counts. But the @batumiraptorcount.org people had some important comments
#conservation #ornithology 🧪🐾🌎

HALF A MILLION RAPTORS! 🦅

After a few slower days (~30K+), #BRC17 hit the absolute jackpot yesterday!

Around 11 am, the floodgates opened — massive streams of Honey Buzzards & Black Kites pushed us past 100K raptors in a single day! Bringing the season total to 540K😍

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Video by Zülfü Farajli

Things are really kicking off now at #BRC17. Although by no means the most diverse period for raptor migration in Batumi, there is little as humbling as standing below a sky filled with thousands, tens of thousands, or even over a hundred thousand Honey Buzzards ‘marching’ onwards to Africa.