Females here and elsewhere

The two chicks of Pistache F11 on nest just before fledging 25 July 2025

Once again this year the females (at least those that we know about) released by Nos Oiseaux have “out-bred” the males of the project. Dominique Lorentz has told us that Mouche (PR4) and her partner AM06 have fledged two young in the French Department of Moselle – the fifth successful breeding of this pair. Pistache (F11), rediscovered for the first time since she was released in Switzerland in 2018, paired with an unringed male and fledged two young (photo above) in the French Department of Marne, as reported by Julien Rougé. This was particularly reassuring news, the nest being on top of a rather dangerous type of medium-voltage electricity pylon, stressing nearly everyone – except apparently the birds themselves.

In the German Province of Baden-Wurttemberg, Chronos (ex-PS9) and her partner (named Kepler last year), sadly failed this season. After two years of successful breeding, Chronos incubated long past the time when her eggs should have hatched. Daniel Schmidt thinks that the most likely cause might be damage to the eggs by pine marten Martes martes, although due to a technical problem with the camera-trap, the reason for the failure will remain unknown.

As for the females in Switzerland, 2025 has been exciting since two unringed immatures around 2-3 years old spent much of the summer with two territorial males in the Three-Lakes region, Olympe (F28) and Racine (F29). In both cases, intense courtship, mating and nest-building activity was observed, generating high hopes for 2026… provided of course that all return safely from migration next spring. Arthur (F12), our most famous male, has continued to be on the lookout for a passing female, using the two platforms installed for him at Hagneck and – as in past years – also building at least one additional nest by himself.

Migration has now started, the two summering females have already left, and we continue to keep a close eye on “our” males until they head south in the coming 2-3 weeks.

 

Mystery solved

Osprey Arthur F12 posing at Hagneck, Lake of Bienne, Switzerland

On June 29, thanks to 41 observers stationed in the Trois-Lacs region with a few also in the Aar and Doubs river basins, we discovered that at least five Osprey are spending this summer in the Three-Lakes region. This second Osprey Morning of the season demonstrated once again how a simultaneous observation covering as many potential fishing sites as possible (26 in total) helps to better understand the real situation, especially at a time of year when many birders are off on holiday or up in the mountains.

The first Osprey was heard at 05:09 at Hagneck, Lake Bienne, where one was later seen (and identified as Arthur F12) at 06:58. Around the Fanel Nature Reserve on Lake Neuchâtel, there were a number of participants triangulating between the jetty of the Thielle, the ALA and Nos Oiseaux observation towers, and the jetty of the Chablais du Cudrefin. They saw their first Osprey (eating a fish) at 05:24, which was then lost from sight at 05:44. Between 06:20 – 07:36, either the same individual or another was observed, again eating a fish, while a second Osprey was spotted from 07:25 – 07:40. At 07:57 a blue-ringed male (likely Racine F29) was seen perched before making eight half-hearted fishing attempts from 08:38-08:44 while being mobbed by a Common Tern and a Black Crow. He was eventually lost from sight at 08:55, flying towards Le Landeron.

Back to Hagneck, the sudden arrival of Racine at 09:17 (who had previously already been seen visiting the other two males in the area) immediately triggered territorial defence behaviour from Arthur against the intruder. Regarding the other Osprey seen earlier in Fanel at the same time, it was probably an immature unringed female, which has been observed several times with Racine since June 4.

Meanwhile further south-west in the Grande Cariçaie, five other teams recorded two different Osprey: Olympe (F28) and an immature unringed female. Olympe was first seen in a display flight with a fish in his talons at 05:38. A similar behaviour was seen again at 08:28, when he brought the fish he was carrying to one of his nests, where an unringed female was then seen eating it nearby at 08:42. So two birds were definitely counted in that territory, just like during the last Osprey Morning on June 15. But the big question remained: was this female the same one seen at Fanel – at the same time as Racine – until around 07:40, and which may have joined Olympe an hour later? Or are there actually two different unringed females in the region, as we have been suspecting for quite some time already?

Fortunately there were three other teams spread around Lake Morat, and one of them spotted an Osprey (being chased by a Yellow-legged Gull) over Salavaux at 08:42. Definitely not Olympe or “his” immature unringed female, nor Arthur or Racine. A good possibility is that it was the unringed female which had left Fanel around 07:40. So the results of this second Osprey Morning seriously support our suspicions that at least two unringed females are discretely spending this summer in the Three-Lakes region. An impression further reinforced on June 30th, when Racine was seen perched next to an unringed female, in a place where one team had spent the entire morning of the 29th without seeing a single Osprey!

Big thanks go to all the team, including of course those not lucky enough to be at sites where Osprey were seen. Since we can never predict where one (or two) Osprey might turn up, and the species never seems to do the same thing from one day to another, it is crucial to cover as many observation spots as possible at the same time. It is also fundamental to start the watch at dawn, to increase the chance of seeing the birds catch or eat their first fish of the day – with the added benefits of escaping a heatwave (very intense on June 29th), and also to observe a multitude of other interesting species.

Mystery of an unringed female

Sunrise over the Fanel Nature Reserve, Switzerland, by Luc Villarejo

The first Osprey Morning of this year took place on Sunday 15 June and started with a slight panic, when two participants were locked inside the Cudrefin campsite as they had been given the wrong code to get out. Fortunately they then managed to cleverly escape via an “unofficial exit”, so were still able to get to their observation post on time. Just one illustration, among so many others, of the dedication of the 44 volunteers who got up well before the crack of dawn to look for Osprey from 23 different observation posts. At least this time everyone was able to enjoy a magnificent sunrise, quite different from our first Osprey Morning last year!

The day then got off to a flying start, with our three known males of the Three-Lakes region, as well as an unringed female which has been observed sporadically in the region since mid-May, all being spotted before 6am. Arthur (F12) was seen flying from the Aar River towards Hagneck at 05:40, where he chased away a pair of Egyptian Geese before leaving for a fishing trip, reappearing with his breakfast at 06:13. He was particularly active from 08:16 until after 10am, bringing many branches to a new nest under construction. Let’s hope that a violent storm that hit the region in the afternoon with winds up to 142km/hour (causing many broken branches, uprooted trees and even the cancellation of a music festival in the evening) won’t have damaged this nest (not visible as it is masked behind a small wood).

At the Lake of Neuchâtel, another Osprey – almost certainly Racine (F29) as his ring was read later – seemed to be perfectly synchronized with Arthur, as he was first seen between Fanel and the Thielle jetty at 05:40, before having his breakfast at 06:22. However, the “early bird” prize went to two other Osprey – Olympe (F28) and an unringed female – spotted together in the Grande Cariçaie between 05:25 and 05:30, with one of them then catching a fish at 05:46, and Olympe capturing another one at 09:40. However, surprisingly none were seen elsewhere, either in the Aar and the Doubs River valleys, or around Lake Morat. But we know only too well how discrete the species can be at this time of the year!

While Racine seemed to spend most of the Osprey morning all alone at Fanel, the next day it was his turn to be spotted in the company of an unringed female. Was it the same one that visited Olympe the day before, or could there possibly be two different females hanging about? A key goal for our next Osprey morning will be to try to solve this mystery. Until then, many thanks to all the team who participated on 15 June (keeping in mind that not being lucky enough to see an Osprey during this morning is as valuable for us as having seen one). We are still looking for volunteers to search for Osprey at good fishing places for the next Osprey morning on Sunday June 29. So if you are ready to get up very early in the morning (taking advantage of the day before it gets too hot), please feel free to sign up here!

Females in the spotlight

Female Osprey Pistache F11 at her nest in the Marne, by Alain Balthazard

After Plume (F02) in north-eastern Bavaria (Germany) in 2021, Mouche (PS4) in Moselle (France) since 2021, and Chronos (ex-PS9) in Baden-Württemberg (Germany) since 2024, we have received the great news that another one of our females, Pistache (F11) was recently discovered breeding in the French department of the Marne (photo above by Alain Balthazard). Seen for the first time after nearly seven years on March 11 in the department of the Meuse, she has partnered with an unringed male and is nesting on an electricity pylon, approximately 270km away from the Bellechasse release site. The nest is about 6km away from the only other pair known in the department, and observers from the LPO and others are monitoring them carefully.

At the same time in Switzerland, one of our territorial males paired with an unringed female last month. All seemed to be going for the best, with the male bringing regular offerings of fish, fixing up the nest chosen by the female, and mating often. Until a week later, when the female suddenly disappeared. However, another unringed female then joined him around mid-May. While it is now a bit late for them to breed this year, we are watching the area closely.

The two Osprey Mornings scheduled on Sunday June 15 and June 29 will hopefully provide new insights and perhaps even some birds that haven’t been found yet. As usual, various observation points will be in the Three Lakes region, and we will also try to focus more this year on favourable sites in the Drugeon, Doubs and Aar river basins. If you have already signed up for one or both mornings no need to recontact us, but if you haven’t yet and are interested in participating, please contact us here.

2024 Project Report

Arthur F12, male osprey in all his splendour in Switzerland, by Thomas Bachofner

The 2024 Osprey Project report has been published (in French only) in the March 2025 edition of the journal Nos Oiseaux.  At least three males from the Swiss reintroduction project (Arthur – photo above by Thomas Bachofner, Olympe and Racine) were confirmed back in the Three Lakes region in 2024, with a possible fourth (Flamme ?) in the French department of Doubs. Two of our females again bred successfully: Mouche produced two young in France (Moselle), while Chronos fledged three chicks in Germany (Baden-Württemberg), along the Rhine River.

An unringed female spent much of the summer in the Three Lakes region, and received visits from all of our three territorial males. However, from her plumage she appeared to be probably only two years old, thus still too young to be interested in males.

Two “Osprey Mornings” were held in June 2024, as well as – for the first time – a more targeted “mini-Osprey morning” in July. In addition, two new nest platforms were built in the Haut-Doubs, in neighbouring France.

The next two Osprey mornings this year are scheduled for Sunday, June 15 and 29. Observation points will be, as in 2024, in the Three Lakes region, as well as in the Drugeon, Doubs and Aare River basins. Anyone interested in participating in one or both of these mornings can sign up here.

The 2024 report can be downloaded here.

A big day

Osprey Arthur F12 the day he arrived to Hagneck by Stéphane Aubrey

The Osprey season seems to start earlier each year. After the surprise sighting of Pistache F11 in France on March 11, we received the first good news from Switzerland on March 22, when Martin Zimmerli spotted Olympe F28 back in the Grande Cariçaie along the shores of Lake Neuchâtel. Then on March 24 Fabian and David Grossenbacher saw another bird, presumably Arthur F12, back at Hagneck. This was soon confirmed by Stéphane Aubry, when he not only photographed Arthur (above), but Racine F29 as well. The same day Martin Zimmerli saw an Osprey at Fanel, most likely Racine even if his rings could not be seen. Racine does get around, but we really do want him to meet a female, not just another male!

March 24 also brought us good news from Germany: Daniel Schmidt-Rothmund informed us that Chronos (ex-PS9) had just returned to her nest in Baden-Wurttemberg, 5 days after her male had come back (in 2024 she had returned 4 days after him). Her partner was baptized “Kepler” last year, when the pair fledged three chicks. Let’s hope that they will be successful again this season (see below one of this year’s first camera-trap photos of the pair).

Finally, Dominique Lorentz tells us that Mouche PR4 and her male AM06 have also safely returned in the French department of Moselle (one bird was seen on March 17, and then both together on March 19). The dead tree where they successfully bred during the past four years fell down in January, and they are now setting up housekeeping on a nearby platform that was “preventively” built for them two years ago (as it was clear that their nest tree would not last for long). While it is sad that their natural nest is gone, the pair immediately adopted that platform to establish their new nest, which shows how important it is to provide platforms for Osprey.

Ospreys Chronos (ex PS9) and Kepler arrive to their nest in Baden-Württemberg
Ospreys Chronos (ex-PS9) and Kepler arrive to their nest in Baden-Württemberg

First surprise of the year

Osprey Pistache F11 migrating over France

An Osprey flying over France with a blue ring on her right leg—that was what Stéphane Mikaelis photographed on March 11, 2025. The bird was seen flying north (with a nice meal in her claws, see photo above), not far from the lac du Der in the French department of the Meuse. Fortunately her colour ring was readable: F11. Also known as Pistache, F11 is a female born in Norway and translocated to Switzerland on 5 July 2018. After being raised in the aviaries at Bellechasse and then released on 14 August, she left on migration on 8 September, 2018. Almost seven years had passed with no news of her, until we received the amazing photo from Stéphane. The discovery of Pistache brings the number of known returnees in Europe to 12, which corresponds to a rate of 19.4%, very good for a project of this type.

It is well known that male Osprey are very philopatric, almost always coming back to breed in the region where they first fledged. Females, on the other hand, usually move to another population to find a partner. Was Pistache on her way to the important Osprey population in eastern Germany, where another of our females released the same year, Plume (F02), had already been observed breeding?

In any case, 2018 was a very special year, as that was also when our male Arthur (F12) was released – and he has been returning to Switzerland every year since 2020. While it shouldn’t be long until the first Osprey of the season are seen in Switzerland, we are holding our breath to see him back again this spring!

Osprey chick Pistache F11 the day she was collected.
Osprey chick Pistache F11 the day she was collected, 5 July, 2018.

Wintering in West Africa

Where do “our” Osprey go in winter? Up to now, at least two birds released in Switzerland have been seen wintering in West Africa. John Wright first photographed an unidentified male from 2016 in the Langue de Barbarie National Park, Senegal, in December 2016. Fusée (PR9), also from 2016 (the same individual?), was then spotted about 20 km away in the Trois-Marigots wetland by Jean-Marie Dupart in September and October 2018, and photographed in the same place by Marc Steinmetz in February 2019. It was then the turn of Flamme (ex-KF6), from 2017, to be photographed by Chris Wood and Joanna Dailey in Gambia, at the Gunjur Quarry wetland, on March 2, 2020.

In December 2024 we (Denis Landenbergue and Wendy Strahm) spent three weeks prospecting along the coast of Mauritania (with Abou Gueye), Senegal (with Jean-Marie Dupart), and Gambia (with Fansu Bojang), hoping to find one of “our” birds. Out of nearly 400 Osprey counted in total, we could read the codes of 20 colour rings in Senegal and Gambia, originating from Germany (8, black on left leg), Scotland (4, blue on left leg), France (3, orange), England (3, blue on right leg), Wales (1, blue on right leg) and Norway (1, black on right leg).

We also saw 4 other colour rings that could not be read in Mauritania, 3 in Gambia, and 6 in Senegal. Over half of the birds observed were unringed, and the others were either too far away or their legs were not visible. Above are a few photos of some of the more cooperative birds.

We now eagerly await the end of March when the first Osprey will start returning. As always, in order to identify territories of summering Osprey in Switzerland, we will hold two “Osprey mornings” this year in the Three-Lakes region and the trans-boundary Doubs river basin, on Sunday 15 June and Sunday 29 June 2025. More details about this will follow, but, in the meantime please reserve already these dates in your diary!

Heading South

Hagneck Nature Reserve, Bern, Switzerland

While it is never easy to know exactly when “our” Ospreys head south, thanks to some very avid observers we are pretty sure when they started their migration this year. Arthur (F12) at his usual territory in Hagneck (photo above) and Olympe (F28) in the Grande Cariçaie were last seen on 6 September, while the last observation of Racine (F29) was on 1 September. Vicky, the immature female that spent the summer in the Three Lakes region where she was visited at least once by each of our males, left earlier (as females tend to do). She was last seen on August 17.

As for our two known breeding females outside of Switzerland, Daniel Schmidt-Rothmund told us that the last photo-trap image of Chronos (ex-PS9) at her nest in Baden-Württemberg was on August 13, and of one of her three young on the 14th. A great surprise was then to discover that one of them (identified by its black ring code) was seen on August 24 in the Ebro Delta in Spain, over 1,100 km away south-west from its place of birth.

From Moselle, Dominique Lorentz reported that Mouche (PR4) was last observed near her nest on 30 August. We were then delighted to learn that Patrick Roux photographed her on September 6, on her way south, in the French Department of Côte-d’Or (Burgundy), about 240 km away from her territory. Both of her young had last been seen together on September 9 near the nest, before the final sighting of one of them on the 10th. With migration still underway and the wintering season coming soon, we of course hope to have more surprises in the next few months.

One Osprey can hide another

2 female osprey, Vicky and Cléo, in Switzerland 29 July 2024

In an area rarely visited by bird-watchers in the Three-Lakes region, an unringed immature female (baptised Vicky) was regularly observed from July 4 (although she was probably there earlier), and last seen on August 17. It seems that she left on migration around the middle of the month, but was so discreet that we don’t know exactly when.

A nice surprise was the visit, from July 29 to August 2, of another unringed female (this time an adult) in the same area. She had a distinctive plumage with a heavier collar and different underwing pattern (see photo above). While all three of our territorial males were observed visiting the area that these females were using, no display flight or other nuptial behaviour was noted – possibly due to Vicky still being immature.

Without being able to read a colour ring, or to compare each bird’s plumage from photos, it is very difficult to tell one Osprey from another. The challenge of recognizing local birds gets even greater when autumn migration is under way, with birds from elsewhere passing through Switzerland and sometimes stopping over for a few days.

To date our three males are still around: Arthur F12 (last seen in 2023 for sure on September 1, and possibly even until the 10th), Olympe F28 (last seen in 2023 on August 29), and Racine F29 (last seen in 2023 on September 5). All three are now getting ready to migrate soon!