British migratory Ospreys have many challenges on their journeys to and from West Africa, so it was very encouraging, earlier this month, when the young male (colour ring blue 22) returned to Poole Harbour and paired up with his mate, blue CJ7. He had first returned last May as a two-year-old, too late to breed, but with plenty of time to establish a pair bond with CJ7. Blue 22 had already met this female when he was released from the hacking cages in 2019, as part of the translocation project we are running with Birds of Poole Harbour, under licence from NatureScot. That was CJ7’s third summer in the area, having been seen at Poole Harbour for the first time in August 2017. The two birds looked very settled once they were reunited this spring, and on Saturday we were delighted that CJ7 laid the first egg. You can watch the nest live via the Birds of Poole Harbour webcam.

We collected blue 22 from nest B01, not far from Roy’s home in Moray, on 11^th July 2019. He was one of a brood of two and in excellent condition – 1500g is a good weight for a male nestling. Tim and Ian Perks drove south with the eleven young ospreys on 12^th July. You can find out more by listening to one of the podcasts we made in 2019.

The team at Poole Harbour had built new hacking cages at a secluded location and all 11 young birds thrived on a diet of fresh trout.  Blue 22 was released on 4^th August and after four weeks of feeding up on fresh fish, set off on his migration on 1st September.  Two others also started their migrations on the same day. 

That first migration is crucial, and so is the first winter when young Ospreys are often bullied away from the best feeding areas by the wintering adults. They usually remain in West Africa (or Iberia if they have only migrated that far) for the whole of their second calendar year and this gives them the opportunity to get established at a specific site, before the older birds return in the autumn.  If they prove to be winners in the Ospreys’ world then they could return to the same place each winter for two decades or more.

Blue 22 may have started with an advantage for he came from eyrie B01. The oldest and most used nest in Moray – first established in 1966 when there were only two other pairs – both in Strathspey. Most northern Ospreys know this clump of old trees – it’s a favoured eyrie – for them and for us. The female Logie bred here, the first Osprey we tracked with state-of-the-art GPS transmitters in 2007. Morven took over from her in 2008 and wintered in Mauritania; 15 years later she is still breeding in Moray although unlike most Ospreys she has moved nest four times. Satellite tagged males Nimrod and Yellow HA also bred here – it’s a special place. 

Blue 22’s father is unringed but distinctively very white breasted – he kicked out the resident male in 2016 and reared three young. Next summer there were three young, then two young for two years, but in 2020 the pair lost the brood when very small. Last year, he failed to attract a mate so instead he built an extra nest in the big pine next-door – the location on the original 1966 nest when the tree was alive. This year he’s attracted mate and a check and a check this morning showed the female incubating their first egg and her mate perched close by preening. So this year he’s just behind his son – yet 500 miles apart.

Meanwhile what about blue CJ7’s pedigree? She was one of two chicks to fledge from a nest known as Site K near Rutland Water in 2015. Her mother, 00(09) fledged from the Site B nest in Rutland in 2009 and is the daughter of a male osprey 03(97) who was the first transloctated Osprey to breed at Rutland Water and raised a total of 32 chicks between 2001 and 2015. Colin Crooke and Roy collected this young Osprey on 11^th July 1997 from a regularly used eyrie near Dornoch in Sutherland. 03 was part of the second cohort of young Ospreys translocated to Rutland Water. CJ7’s father, 06(09), fledged from the Site O nest in Rutland in 2009 and was an offspring of a translocated male 06(00) that Roy and Bob Moncrieff collected from a nest in Strathspey on 10thJuly 2000. That bird’s father, and thus CJ7’s great-gradfather was orange/black SB – one of three young ringed by Roy at the RSPB’s famous Loch Garten nest in 1993. 

CJ7 has never been seen back in the Rutland Water area, but that is not surprising, because females often disperse to join other Osprey populations. CJ7 was first identified at Poole Harbour by Tim on 8^th August 2017. That day she was seen interacting with the first cohort of translocated Ospreys who had just been released. She has continued to return each summer since, clearly encouraged by the presence of young Ospreys in the area.  In 2019 she paired up with a two year-old translocated male, but sadly he failed to return the following spring. Now, finally, she is breeding for the first time, with 022.

 As the years have passed we have got to know individual Ospreys for many years, while others are never seen again after they depart on their first autumn migration. Longevity and breeding success involves luck and being in the right place at the right time. Surviving the early years in Africa and on migration, then finding a good nest site and a successful partner. A female needs to be bold and strong to defend her eyrie from all intruders, to protect her young and to get as much fish as possible into her brood; and her mate needs to be dominant at the fishing grounds and a very skilled fisher. That’s the essence of a being an Osprey pair that lives long and creates a dynasty. Let’s hope CJ7 and 022 have that luck and those skills, and help to re-establish the ‘mullet hawk’ back on the South Coast of England for the first time in more the two centuries. We are proud to work with the Birds of Poole Harbour team, aiming to restore a new dynasty of Ospreys on the coasts of the English Channel.

Roy Dennis and Tim Mackrill

2021 is proving to be an encouraging year for the Poole Harbour Osprey Project, which we run in partnership with Birds of Poole Harbour and Wildlife Windows.

The long term aim of the project is to restore a population of Ospreys on the South Coast of England, where they have been absent for 200 years. This involves the translocation of young from nests in Northern Scotland. You can learn more about the project in our podcasts here.

Young Ospreys usually return to the UK for the first time in their third calendar year, and so this spring we were hopeful we would see some of the birds released in 2019 back in Dorset for the first time. Satellite tracking studies have shown that young Ospreys wander widely when they first return, but they usually visit their natal site (which in the case of the translocated birds is the release site) at some point during their first summer back in the UK. A key part of this behaviour is to prospect potential breeding sites, and, as a result, young birds often intrude at active nests. The movements of satellite-tagged male Rothiemurchus when he first returned to Scotland in 2011, is a good example of just how far young birds wander before they establish their own nest site.

In the early years of colonisation, it is usually males who establish territories, before attempting to attract a mate, but the difference for any returning male to Poole Harbour this year, was the presence of an unpaired female. CJ7 fledged from a nest in Rutland in 2015 and has returned to the Poole Harbour area each summer since 2017. It seems that the presence of translocated juveniles in the area has been a key factor in her settling in Dorset. She paired with a translocated bird, LS7, in 2019 but sadly the young male failed to return from migration last spring. Unperturbed, CJ7 has remained faithful to the same artificial nest for the past two summers and has laid unfertilised eggs on each occasion, demonstrating her eagerness to breed.

As those of you who have watched the Birds of Poole Harbour live stream this summer will know, there was great excitement on 18th May when CJ7 was joined at the nest by 022, a male that we had translocated from a nest in Strathspey in 2019. The two birds paired up immediately, and were seen mating regularly. It is highly unusual for two year-old Ospreys to breed, but we were hopeful that CJ7 may lay eggs in late May. That did not happen, but the two birds have remained together since, and, assuming they both return from migration, we are hopeful that they will attempt to breed next spring. What is not so certain is with nest they will choose – in recent weeks they have been seen at various artificial nests around Poole Harbour, and have been interacting with this year’s newly-released juveniles, even perching on nests with them.

Whilst the key long-term aim of the project is to restore breeding Ospreys to the South Coast of England, early evidence is showing that this new population will also help to link different populations of Ospreys. The presence of translocated birds in and around Poole Harbour has led to CJ7 taking up residence in Dorset, while a female that we translocated to Poole has bred successfully in Wales for the first time this summer. 014, a female released in 2018 has bred for the first time this year at a nest at Pont Croesor in the Glaslyn Valley near Porthmadog in North Wales. She raised a single male chick (ring number 494), with a four-year-old male, Z2 or Aeron, from the Cors Dyfi nest in mid-Wales. Meanwhile a second female, 019, released at Poole Harbour in 2019, was also seen in Wales earlier this summer. She was captured on camera when she visited the nests in the Glaslyn Valley on 5th June. This was the first sighting of her back in the UK, although she was seen on a number of occasions at Gunjur Quarry in The Gambia during her first winter and again in March this year. She was subsequently seen at Cors Dyfi further south in Wales on 30th June and possibly again on 5th July. This demonstrates how widely young birds wander when they first return; helping them to develop important knowledge of where other Ospreys are breeding. It will be very interesting to see if and where the young female appears next spring. Research has shown that male Ospreys typically breed close to their natal site, but females often disperse further, and so it is possible that 019 may follow 014’s lead and also return to Wales in future years to breed. Or should another translocated male return and set-up territory at Poole Harbour, we may yet see her back in Dorset.

A key element of the project at this early stage is the continued release of young birds, and during July we translocated a further ten juvenile Ospreys from nests in Moray and Highland. The young Ospreys are collected under a special licence issued by NatureScot from broods of two or three and then held temporarily at Roy Dennis’s home near Forres, before being transported by road to Dorset. You can hear more about our work collecting Ospreys by listening to one of our podcasts from 2019 here.

Once the birds had arrived at Poole Harbour on 15th July they were immediately moved into holding pens and monitored by the Birds of Poole Harbour team. CCTV cameras enable the birds to monitored closely during this period and released when appropriate. The first five birds were released on 2nd August with the remaining younger birds making their first flights ten days later.

The post-release period is critical in the imprinting process because it is when the young Osprey learn that Dorset is home. They generally remain close to the release pens for the first ten days, before venturing further a field and exploring the wider landscape. Fresh fish is provided by the team on a daily basis in order to replicate what happens at natural nests, and so even when the young birds make longer exploratory flights, they usually return in the evening to feed. Most young Ospreys do not catch their own fish until they depart on their first migration, and so the fish provided by the project team is essential in helping the birds to get into the best possible condition for the long flight south.

In the last few days the juveniles have been seen in the presence of CJ7 and 022. At Rutland Water there were instances of non-breeding adults feeding translocated juveniles, and we wonder if that may be repeated in Dorset this summer. Both 022 and CJ7 tolerate food-begging juveniles perching on artificial nests with them, and it will be interesting to see if they respond to the incessant food-begging, by providing fish. Regardless, the presence of the young birds will further strengthen the very strong bond that both CJ7 and 022 already have to the area.

This year’s juveniles are likely to remain at Poole Harbour until early September before setting off on their first migration. An excellent way of seeing them before they depart is to join one of the Birds of Poole Harbour Osprey cruises. You can find out more here.