"I'll be back" said an Austrian 'actor' in a 1980's sci-fi movie.

Bird migration is a fascinating concept - moving between parts of the world, on an annual basis, based purely on the bird's requirements at any particular time during that year. Many animals migrate of course, from butterflies to bats, whales to walruses, salmon to sloths. Perhaps it is bird migration that grabs the imagination the strongest, however - possessing adapted reptilian scales formed into feathers which enables a bird to simply up sticks, and be literally the other side of the world a few days later.

Terns, cuckoos, swallows, geese, in fact, almost all bird species that fly (around 40 bird families are flightless, but even some of these migrate - penguins, for example) migrate to some extent. Even that garden favourite that you have been feeding and observing through the kitchen window, the robin, is highly unlikely to be the same bird from one year to the next. My particular favourite migration specialist is the Manx Shearwater. Wales is home to the greatest congregations on earth of these remarkable birds and one particular bird, ringed in 1957 on Bardsey Island, is estimated to have travelled over 5 million miles throughout its lifetime. That's 20 times to the moon and back! They travel across the Atlantic Ocean each autumn to the waters off Brazil and Argentina, only to come back to the very same nesting burrow the following spring.

Can I have twenty return tickets from Bardsey Island to the moon please..

Every time I see ospreys depart their nests for the last time here in the UK each August and September, I can hear those words "I'll be back" in my head (yes, in a dodgy, hybrid European-American accent too). We all want to see our ospreys return six/seven months later, but how likely is it that they actually will come back? The following is an attempt to put some quantifiable science behind the chances, in terms of percentage, for particular birds to return to the Dyfi over the next few weeks.

Please bear in mind this is not an exact science, just an attempt to put some figures on particular individuals with the information we have to hand.

Monty & Nora
Well, let's start off with the good news. Many studies over many years from many counties for many migrating populations all say the same thing. It is established, full-adult birds that have the greatest chance of returning. Years' worth of life experiences and migrations pay off. In the UK, this return rate is high, less than one in ten adult ospreys fail to make it back the following year. Probability of Return = 90+%

The Class of 2011

These three ospreys were the first offspring of Monty and Nora. If alive, we would expect them to return to the UK two years later, probably around May/June, 2013.

Leri
Sweet little Leri. She began her migration on September 13th, 2011 and had successfully reached Senegal by October 2nd. For the next three weeks she travelled around 400 miles northwest towards the Senegalese coast until October 24, when she was just a handful of miles from the coastal town of St. Louis. Then the tracker started sending signals back from the same position for almost a week and then stopped sending data back altogether.

Nothing happened for over six months and then, suddenly, the tracker started sending signals back again - from the same place as the previous October. Clearly, the tracker hadn't moved significantly, maybe just enough to expose the solar panel on it to sunshine to kick it back into life. Location data from the same area was sent back until August 2012, then nothing again. The resurrection of the tracker coincided with the rainy season - had flowing water turned the tracker upright, facing the sun? Probably.

If there is any chance that Leri is still alive, the tracker would have had to have fallen off her on October 24th. Despite many attempts, our friend Frederic has been unable to find Leri's tracker (the area is very swampy and overgrown). Has a UK osprey ever returned two years later with its tracker having fallen off somewhere? Actually, yes. Once.

If Leri has survived post-October 2011, for her to return, of course, she would still have had to survive for another two years almost in Africa. Probability of Return ≤ 5%

Leri, boss of the Class of 2011, rests on her favourite perch

Dulas
Dulas was very close to Leri, having his sister constantly bossing him around. Despite being blown wildly off course as soon as he started his migration on September 12th, 2011 (he spent his first night of independence on an offshore wind turbine off the coast of Essex!), Dulas had made it safely to Senegal just two weeks later on September 27th. He settled on the Gambia River for the next few months, but decided to head south on January 15th (2012) - one day before Janine got to his Gambian location for the previous three months!

A couple of days later, Dulas settled on a huge estuary system in Guinea-Bissau. Everything was going great, he celebrated his first birthday on the estuary several months later on June 6th, but then six weeks later on July 13th, we lost contact.

Despite making it to over 13 months old, Dulas is in a similar position to Leri. His only chance really is for his tracker to have either fallen off completely, or to have suddenly stopped working. Knowing Dulas made it to his first birthday, plus not knowing the tracker's history post-July 13th, gives Dulas a slightly greater chance of having survived past this date.  Probability of Return ≤ 10%

Warm and snug in an osprey nest in Wales one night - on a massive wind turbine in the North Sea the next..

Einion
Well, I'm going to have to be honest here. Einion was the favourite of most of us at the Dyfi Osprey Project in 2011. What a conservation story - the first osprey to hatch on the Dyfi for over 400 years. Einion was fiercely independent, rarely interacting with his brother or sister. The famous artist Terrence Lambert even produced a painting of the very moment Einion entered the world.

Stunning painting by Terrence Lambert - mounted prints are for sale at the Dyfi Osprey Project (not many left now) 

He was so independent, Einion had started his migration before August was out. By September 9th he had reached Casablanca, Morocco, and stayed just to the south of the city for three weeks taking in the sights. By early October, Einion had made it to the Somone Lagoon in Senegal - a favourite place for wintering ospreys. It's so nice in fact, a few weeks later Roy Dennis travelled down to the lagoon - and actually found Einion!

Einion, too, made it to and past his first birthday; although by this time last year, he had found a new base. A coastal lagoon just to the south of St. Louis, Senegal, and just 20 miles away from his sister Leri's last position.

By July 15th last year, however, Einion's tracker was sending back some worrying signals. Not about Einion himself, but about the voltage take of the tracker's solar panel. In just one week, the voltage decreased from a healthy 4V (which it should be) to under 3.5V, too weak to send signals back. Here's the important thing though - Einion was moving around perfectly normally during this week of the failing tracker.

I've just looked at Einion's last 10 days of GPS signals again. I'm convinced, as I was last year, that he has survived the failing tracker. In a rush to get three trackers in 2011, we managed to get two brand new units and one reconditioned unit. This older unit had already been to Africa on a Lake District osprey the year previous in 2010; that bird unfortunately died the following January. It is this reconditioned tracker that Einion had. Coincidence?

Wildlife photographer Andy Rouse took this stunning image of Einion in 2011, just before he left for Africa (Einion, that is, not Andy!)

Einion looked a strong bird here on the Dyfi in the summer of 2011. He migrated successfully to good fishing areas in west Africa and made it well past his first birthday. Assuming Einion made it through the tracker incident, we 'only' need him to survive another 10 months and successfully migrate back from Africa to make it back to the UK. Probability of Return = 75%

The Others

What about other ospreys? We've seen several ospreys on the Dyfi over the last few years. A Glaslyn 2008 osprey, White YC,  made several visits to the Dyfi nest in 2011; we didn't see him last year but he could well be around somewhere. A Rutland 2009 female, Blue 00, was around in 2012 as a three year old non-breeder; she was also spotted several times in Rutland - will we see her this summer?

There are two birds in particular however, that we have high hopes for:

Dai Dot
This is a male osprey that visited the Dyfi nest several times in 2012. He's regularly seen on a favourite perch on the estuary around four miles away from the nest and made a right nuisance of himself at the end of last summer landing right beside Ceulan on the nest several days running.

More significantly perhaps, is the fact that Dai Dot was also around in 2011. We even managed to video him hovering above the nest. All this means that Dai Dot calls Dyfi home - he doesn't seem to wander off, which is what you'd expect for a male bird of three of four years of age. Probability of Return = 80%

Dai Dot - named after his two very characteristic white dots above his skinny beak - will he come back in 2013?

Blue 12
This is a Rutland female, born in 2010. She was spotted in 2012 both on the Dyfi and Rutland Water. This is completely normal behaviour for a two year old female - prospecting around the country for a good breeding site and a half decent male with a nest to entice her.

Significantly though, she was spotted on the Dyfi last year several times, right from May to August. She is also related to Nora. Blue 12's mother is Nora's sister, which makes her Nora's niece! Will we see Blue 12 again this year? Probability of Return (to the Dyfi) = 75%

Keep it in the family. Blue 12 visits her Auntie in Wales in 2012 - several times

So there we are. Ospreyitis is just about kicking in big time again, the months of waiting and suspense are almost at an end, and soon our ospreys will be back from Africa.

Let's hope that the weather is kind and we have a full complement of birds back for another breeding season. It really doesn't look good for Leri and Dulas, but what about Einion? I honestly think the chances of him returning are greater than of him not. Will we spot him though? Of course we will. This week we are putting up an additional SUPER HD camera that has a 360° field of view that will be used for the Live Streaming page on this website. Left, right, up, down - if Einion turns up, we'll see him. Actually, you could be the first person to spot him, watching at home or the office (shh) when he lands on the nest. You'll know who he is - he has a blue ring with the letters DH on his right leg and a useless tracker on his back. He even has Blue 12, his cousin, waiting for him and looking for a mate (is that legal?).

What a story that would make. I can barely imagine it. The first osprey to hatch on the Dyfi in centuries, returns after a two year sabbatical in Africa. Mid May, Alwyn shouts from the Osprey Hide "LARGE BIRD OF PREY APPROACHING" and as he does, a blue leg ring and a tracker come increasingly into view.  

Would you shout, jump for joy, laugh, cry? All of these things? Not long to go now..

KEEP CALM and LOOK UP
 
Einion photographed in Africa in January 2012 - he looks in great condition