# The stork from your yard spends the winter in Africa. Which way does it go?

A stork from Russia, one from Poland and one from Germany carried a GPS transmitter for a whole year. One reached South Africa, one flew over Brașov, one stopped in Morocco. Follow their road, day by day.

By Marius Comper · 21 September 2026 · every position on the map is a real measurement; the sources are under [sources](#surse)

## Three storks, three roads, one map

In the summer of 2013, researchers fitted GPS transmitters to 70 young storks in eight countries. Three of them flew a whole year with the device on their backs. Pick one and follow its year, day by day.

The answer: AR445 reached 9,141 kilometres from the nest, in a straight line. 5P311 reached 7,776, Zozu 1,978.

### A chick near Moscow, with a 66-gram device on its back (21 August 2013)

AR445 hatched in the summer of 2013, north of Moscow. A week before it could fly, researchers harnessed a 66-gram GPS transmitter to its back, about 2% of a stork's weight.

On 21 August it left for the south. The device logged its position every 5 minutes for a whole year; the map shows one position a day, the noon one.

### Over Romania, then the Bosphorus (7 September 2013)

On 31 August, AR445 was over Dobrogea, south of the city of Tulcea. Then it crossed the Bosphorus, the narrow strait between Europe and Asia, over which the whole eastern population flies each autumn.

In the first week of September it was already in Sinai, after flying over Turkey.

### A long stopover in Sudan (1 November 2013)

Young storks do not hurry. AR445 wandered through Sudan for weeks, eating and resting. Experienced adults cover the autumn road in about 26 days; the young take months.

Meanwhile, large flocks of storks travelled the same road toward the same wintering grounds.

### Winter near Johannesburg (27 February 2014)

On 27 February 2014, AR445 was 9,141 kilometres in a straight line from the nest: the farthest point of its year. In flight, along all its detours, it had covered 13,751 kilometres.

It stayed in South Africa until March, then set off back north.

### The return passes through Romania (3 June 2014)

On the way back, AR445 entered the country near Călărași on 28 May and left near Botoșani on 3 June. It spent three days in Neamț. See the clustered points on the map.

At the end of June it was over Ukraine. The nest it had hatched in never appeared on the map again.

### Leaving Poland (22 August 2013)

5P311 hatched in western Poland. On 22 August it left for the south-east, on the eastern storks' busy road: Romania, the Bosphorus, Turkey.

It is the road Romania's storks take too.

### Three days over Romania (28 August 2013)

On 24 August it was over the Mureș valley, on the 25th near Brașov, on the 26th near Oltenița. If you looked at the sky in the south of the country then, that could have been its flock.

On 28 August it had already crossed the Bosphorus. The autumn passage was at its height, and the whole crossing takes less than a few weeks.

### Winter in Zimbabwe (7 January 2014)

On 7 January it was 7,776 kilometres from the nest, in Zimbabwe. It stayed there until March, then started back north.

In July 2014 it was in Turkey. Like AR445, it did not return to the nest in its first summer.

### West first (12 August 2013)

Zozu hatched in southwest Germany. On 12 August it set off west, through France and Spain, a different road from the other two.

And in Spain it stopped for a few weeks before crossing into Africa.

### Winter in Morocco (24 February 2014)

From October to March, Zozu stayed put near Rabat, in Morocco. It is the kind of wintering the study found in four of six young German storks: on rubbish dumps in northern Morocco instead of the long road to the Sahel.

Zozu flew at most 1,978 kilometres from home, 4.6 times less than AR445. By April it was back in Spain.

The Bosphorus is the gate on this road. In spring 2006, 51,958 white storks were counted there, and in autumn between 200,000 and 350,000 pass. The whole eastern population, over 340,000 birds, flies over the strait.

Speed comes from wind and warm air. Tagged storks fly in autumn at 10 kilometres an hour, day and night averaged, and in spring at 6.4. In autumn they cover the road in about 26 days, in spring in about 49, with long stopovers.

## Why they go around the sea

Storks are feathered gliders. They circle up columns of warm air, then slide for kilometres without beating their wings. No warm columns form over the sea, so over water storks must flap, which costs energy.

A thermal is a column of sun-heated air that rises. The stork enters it and circles until it is right at the top, then glides forward, slowly losing height, until it catches the next column. That is how it covers hundreds of kilometres at minimal energy cost.

The young have not learned the trade yet. Against adults, they flap 23% more and burn an estimated 14% more energy in flight, from accelerometer measurements. And the road thins them out: of the 70 young storks with transmitters, 33 were alive after 5 months, only 21 after 12.

The farther they go, the less the flight costs them in relative terms. The birds that reached south of the Sahara flew 3.4 times as far as the ones that stayed north of the desert, but spent only 1.3 times as much movement energy: each kilometre flown south costs less and less.

**At Iskenderun Bay in Turkey the road divides: 30–45 kilometres of sea or the overland detour. Which would you choose for the stork?**

The researchers' answer: adults choose the sea in spring (61.5%), the young detour over land. Crossing costs flapping and energy but brings speed: in spring, 60 kilometres more a day.

## An African arrow, then 50,000 rings

In 1822, a stork with an African arrow stuck in its body was shot in Germany: proof that storks reach Africa. A Danish schoolmaster, Mortensen, then invented the numbered ring, and from over 50,000 recoveries and resightings the map of the roads was drawn.

A ring is a metal or plastic band with a number, fitted to the chick's leg in the nest. Whoever later finds or reads the number reports the place to the ringing centre. That is how the nest is tied to the wintering ground.

The three storks on the map have rings too. Press a ring to see its road.

## In Romania: 3,301 nests counted, over 7,500 pairs

The 2024–2025 stork census, run by volunteers with the Uite Barza! app, gathered 3,301 nests. The organisers believe the country holds over 7,500 pairs in some 1,500 localities.

The previous census, in 2004, found 4,008 pairs in 2,083 localities in 40 counties, and the estimate then was 5,000–6,000 pairs. Today's count has barely begun and its analysis has not appeared yet: 7,500 is the organisers' working estimate (SOR and the Milvus Group).

Romania's storks leave at the end of August and return at the end of March. They spend the winter in South Africa, at least that is what our guides say. No stork from a Romanian nest has yet carried a transmitter like the ones on the map, so its exact road, day by day, is still to be measured.

### Not on 25 March

In the folk calendar 25 March, the Annunciation, is the cuckoo's day, that is when the cuckoo starts singing. For storks, the sources give the end of March, with no fixed day.

## True or false?

Eight statements about the road. Some sound like stories and are true.

- **A young stork from Russia reached South Africa, 9,141 kilometres from its nest.** True. AR445 left the Moscow area on 21 August 2013 and reached the Johannesburg area. The 9,141 kilometres are measured in a straight line between the two points. ([Movebank, data from Flack et al. 2016](https://doi.org/10.5441/001/1.78152p3q))
- **Every stork in Europe winters in Africa.** False. Four of six young German storks wintered on rubbish dumps in Morocco, and the Uzbek storks never left home at all. Same species, different decisions from bird to bird. ([Flack et al. 2016, Science Advances](https://doi.org/10.1126/sciadv.1500931))
- **Eastern storks pass the Mediterranean by way of the Bosphorus.** True. The whole eastern population, over 340,000 birds, flies over the Bosphorus. In spring 2006, 51,958 white storks were counted there, and autumn counts run between 200,000 and 350,000. ([Üner et al. 2010, Sandgrouse](https://osme.org))
- **Storks return to Romania on 25 March, the Annunciation.** False. The sources say the end of March, with no fixed day. In the folk calendar 25 March is the cuckoo's day, because that is when the cuckoo starts singing. ([ADEPT; the folk calendar](https://fundatia-adept.org))
- **Young storks flap their wings more than adults and burn more energy.** True. Twenty-three percent more flapping, measured against gliding, and an estimated 14 percent more energy in flight, from accelerometer measurements. The young do not make up for it by eating or resting more on the way. ([Rotics et al. 2016, J. Animal Ecology](https://doi.org/10.1111/1365-2656.12525))
- **To shorten the journey, storks fly long stretches over the open sea.** False. No thermal columns form over water, and crossing costs flapping flight. The young detour around Iskenderun Bay over land; adults cut only the bay's 30–45 kilometres, mostly in spring. ([Becciu et al. 2020, Functional Ecology](https://doi.org/10.1111/1365-2435.13539))
- **The first proof that storks winter in Africa was a stork carrying an African arrow.** True. The bird was shot in Germany in 1822 and carried an African hunting arrow. Later, numbered rings drew the full map of the routes. ([Storch Schweiz, ringing factsheet](https://www.storchenforscherinnen.ch))
- **Of 70 young storks fitted with transmitters, more than half lived a year.** False. After 5 months 33 were alive, after 12 months only 21. The first year is the hardest: the young fly worse, spend more and do not know the way yet. ([Flack et al. 2016, Science Advances](https://doi.org/10.1126/sciadv.1500931))

## How we know all this

Every position on the map is a real GPS measurement from the open dataset of the eight-population study (Movebank, CC0 1.0 licence). The map shows one position per day and bird, the one nearest noon; distances between points are great-circle segments, and departure day is the first day the bird dropped more than half a degree of latitude southward, by the study's rule.

Comparisons set like beside like: the two maximum distances (9,141 and 1,978 kilometres) are both straight lines between nest and farthest point, and survival is 33 of 70 and 21 of 70. Distances from towns to wintering grounds are straight lines too.

Two figures come second-hand, through the citing studies: the 28-day autumn and 43-day spring passages over Israel, and the 348-kilometres-a-day speed over Israel. The original paper could not be opened.

### What the sources cannot say

- No primary source follows a stork from a Romanian nest to its wintering ground. For our storks, distances are bracketed by the neighbouring tagged birds, not measured.
- One stork with a transmitter is one life, not the species' road. The page shows three birds and says how many there were: 70 tagged, 33 alive after 5 months.
- Positions are noon measurements, not the road flown. Between two points, the bird may draw hundreds of circles after warm currents.
- Bosphorus counts sit below the true number by design: a single watchpoint misses birds, and the study says so.
- The 2024–2025 Romanian census has no published analysis yet; the 7,500+ pairs are the organisers' estimate.

- Flack, Fiedler, Blas, Pokrovsky, Kaatz, Mitropolsky, Aghababyan, Fakriadis, Makrigianni, Jerzak, Azafzaf, Feltrup-Azafzaf, Rotics, Mokotjomela, Nathan, Wikelski (2016). Costs of migratory decisions: A comparison across eight white stork populations. Science Advances 2(1): e1500931. https://doi.org/10.1126/sciadv.1500931 — the eight populations, the Moroccan birds, the ones that stay, flight energy
- Flack et al. (2015). Data from: Migration costs of eight Eurasian white stork populations. Movebank Data Repository. https://doi.org/10.5441/001/1.78152p3q — the GPS positions of the three storks on the map, CC0 1.0 licence
- Shamoun-Baranes, Baharad, Alpert, Berthold, Yom-Tov, Dvir, Leshem (2003). The effect of wind, season and latitude on the migration speed of white storks Ciconia ciconia, along the eastern migration route. Journal of Avian Biology 34: 97–104. https://doi.org/10.1034/j.1600-048X.2003.03079.x — autumn and spring speeds and durations, the three regions of the route
- Üner, Boyla, Bacak, Birel, Çelikoba, Dalyan, Tabur, Yardım (2010). Spring migration of soaring birds over the Bosphorus, Turkey, in 2006. Sandgrouse 32: 20–33. https://osme.org — the 51,958 storks counted at the Bosphorus in spring
- Rotics, Kaatz, Resheff, Turjeman, Zurell, Sapir, Eggers, Flack, Fiedler, Jeltsch, Wikelski, Nathan (2016). The challenges of the first migration: movement and behaviour of juvenile vs. adult white storks with insights regarding juvenile mortality. Journal of Animal Ecology 85: 938–947. https://doi.org/10.1111/1365-2656.12525 — juveniles against adults: 23% more flapping, 14% more energy
- Becciu, Rotics, Horvitz, Kaatz, Fiedler, Zurell, Flack, Jeltsch, Wikelski, Nathan, Sapir (2020). Causes and consequences of facultative sea crossing in a soaring migrant. Functional Ecology 34. https://doi.org/10.1111/1365-2435.13539 — sea or land at Iskenderun Bay: who crosses and at what cost
- Shamoun-Baranes, van Loon, Alon, Alpert, Yom-Tov, Leshem (2006). Is there a connection between weather at departure sites, onset of migration and timing of soaring-bird autumn migration in Israel? Global Ecology and Biogeography 15: 541–552. https://doi.org/10.1111/j.1466-822X.2006.00235.x — arrival over Israel and the daily speeds from the literature
- Schulz (Storch Schweiz). Fachwissen plus: Beringung des Weissstorchs (in German). https://www.storchenforscherinnen.ch — the 1822 arrow stork, Mortensen, the 50,000+ recoveries
- ADEPT Foundation. Birds of Târnava Mare, bilingual guide (in Romanian). https://fundatia-adept.org — leaving at the end of August, wintering in South Africa, returning at the end of March
- NABU Bergenhusen. Romania — 6th International White Stork Census, 2004. https://bergenhusen.nabu.de — the 4,008 pairs in 2,083 localities
- Bytes Europe / Romania-Insider, 4 June 2025. Second phase of international white stork census starts in Romania. https://www.byteseu.com/1073314/ — the 2024–2025 census: 3,301 nests and the organisers' estimate, as reported from SOR and Milvus statements
- GeoNames, RO file (CC BY 4.0), via the locality list of the eclipsele-tale page. https://www.geonames.org — the coordinates of the 42 towns
- Natural Earth, coastlines and rivers at 1:50,000,000 (public domain). https://www.naturalearthdata.com — the map base
- en.wikipedia, White stork (measurements compiled from the Hancock et al. handbook). https://en.wikipedia.org/wiki/White_stork — 100–125 cm tall, 155–215 cm wingspan, 2.3–4.5 kg