Dulas

This is the blog I hoped I would not have to write, not for many more years anyway. We have lost contact with Dulas.

The last blog written on June 6th was a celebration of his first year and all the trials and tribulations he had been through in just twelve months. Six weeks later on July 13th, we received the last transmissions from his tracker. At this time of year he's on a three day cycle so we should have received more data on the 16th, 19th, 22nd and so on; we haven't.

Looking closely at his last set of data everything looks normal up to the the last few hours. On July 13th, the activity reading doesn't move from 09:55 until his last data point at 15:33, meaning the tracker didn't move during this time. We have had no transmissions since then.

The yellow bird denote's Dulas' last position at 15:33 on July 13th, 2012.

Dulas has been in this part of Guinea Bissau for the best part of six months - you can see when he arrived here by the white data bubble on the map above. He's spent most of the time near the mouth of the river with the occasional trip further up stream - something that we really didn't like to see him doing. Why?

One of Roy Dennis' ospreys, Spey, tagged in 2010, made it all the way to Africa and then, at just over a year old, disappeared. Spey's similarity to Dulas is uncanny: both male, both left the UK and eventually made it to this part of Guinea Bissau by their first birthday. Then, suddenly, the trackers stop sending signals. Incredibly, Spey and Dulas' last positions are just three miles apart on the same river. Coincidence?

Just three miles separate Dulas and Spey's last data transmissions almost at exactly the same time of year

We all know the stats. Only around 30% of young ospreys that leave the UK ever make it back in two or three years time, osprey mortality for young birds is high. Satellite tracking research is answering a lot of questions that ecologists have been pondering for years - I think it's true to say that we all thought that a decisive factor in explaining this low return rate was the long migrations that ospreys take, the first one of course, for the very first time. It is starting to appear that this is not the case. The vast majority of first year birds are arriving in Africa safe and well and then surviving many months, sometime longer.

So, what could have happened to Dulas?

1. Natural Causes - we are beginning to learn now that being a young osprey in Africa is tough. Competition from other ospreys, birds, is intense. But now with all the adult birds back in Europe breeding (or attempting to breed), you would think that competition from other ospreys would be negligible. Perhaps he has been predated, maybe he had a disease, maybe he had an accident whilst flying and/or fishing?

2. Human Causes - Guinea Bissau is a desperately poor country, people live on what they can catch and grow in the wild. Yes, people eat birds, yes, people eat ospreys. It's a sobering thought, but Dulas may have been eaten. He could also have been trapped in fishing nets or line - this is a problem ospreys face the world over including in this country where many osprey die each year after getting tangled up.

3. He's still alive - let's end with the positive option. I have spoken to Roy and Tim at Rutand over the last couple of days, they have  been kind enough to look at Dulas' data for us. Many thanks. Just like any technology, it can break. Maybe the tracker on Dulas' back is still there but not working; maybe it has fallen off and ended up upside-down, unable to send any more transmissions. Both Roy and Tim say this is a possibility, albeit remote.

At the end of the day we simply don't know. We are all here at Montgomeryshire Wildlife Trust, staff and volunteers alike, hoping for the best of course. I suppose that if anybody were to spot Dulas return next May or June, we have a good chance here at the Dyfi with all the High Definition cameras and optics we have. Being purely objective however, and saying this with a heavy heart, the probability is that Dulas has become one of the 70% of ospreys that never make it back to the UK. Dulas was a year and 37 days old when we lost contact; absolutely gutted.

The last image of Dulas on the Dyfi in September, 2011 - the following morning he started his migraton to west Africa

Today Dulas is one year old. Actually, he had started to pip out of his egg at the same time as Einion on June 5th, but he had quite a struggle to fully emerge. He finally popped out of his egg at 06:35 on June 6th, 2011. Dulas was already a record breaker - as far as we know, he holds the record for the longest hatching of any osprey in the UK - 42 days.

Dulas always seemed to be in the shadow of his older brother, Einion. He wasn't as independent as his brother and seemed much more aligned with his sister, Leri. It wasn't long however before he was making headlines again. He didn't migrate for almost a fortnight later than Einion, by which time the British weather had turned against him. With 60 mph winds swirling across the UK, we hoped that Dulas would wait a few days before embarking on his southward journey. Right in the middle of the storm on September 12th however, he was off. But he didn't head south - he went east!

Strong winds pushed Dulas off course across Wales and England towards the Essex coast

Then the worrying started. By nightfall he was showing as being 10 miles off the coast of Clacton-on-Sea, Essex, and he was hardly moving. A few metres north, then a few metres west, for hours on end and all at an altitude of 10m. He had surely bitten off more than he could chew for his first long haul flight and perished in the sea, the tide moving his body a few metres per hour as his GPS data suggested?

Gunfleet sands wind turbines - Dulas' first roosting spot away from his nest.

After a bit of research we realised that Dulas had stopped for the night on a series of wind turbines in the North Sea, hopping from one to another which explained his limited movement. Each turbine has a gantry platform 10m up from sea level which accounts for his altitude readings. Perfect!.

The following morning he was off again and Dulas soon corrected his heading once the winds had died down over France. Astonishingly, 16 days after leaving his sister and father behind in a stormy Wales, Dulas had made it to Senegal. A few days later he had settled on the Gambia River where he stayed until mid January.

Then on January 15th, a day before our own Janine got to the very spot Dulas had spent the last 3½ months, he was off. To say Janine was gutted is a bit of an understatement - she had missed Dulas by hours. What she saw however, explained Dulas'  reasoning for leaving. The dry season had taken its hold and where a few weeks earlier there would have been dense mangrove swamps teaming with fish, now there was dry, desolate scrub with a few water holes scattered around - no place for an osprey to hang out.

Panchang, Gambia, where Dulas had spent his first 3½ months in Africa                                                         Janine Pannett

Two days later Dulas was 200 miles south on the huge estuary system of the Rio Cacine, Guinea-Bissau, just to the west of the Guinea border. He's still there today, clearly benefitting from a more reliable source of food, plus taking advantage of less competition from other, more established ospreys who are now back in Europe breeding.

Dulas would make a great after-dinner speaker. In his short one year life he has some truly remarkable stories to tell. Even before he left Wales, he had an almighty tussle with his sister that, at the time, we thought had killed him.

Roy Dennis puts a Blue 99 leg ring on Dulas at his Dyfi nest on July 19th, 2011. An eventful year was to follow.

Behaviourally, Dulas was the exact opposite to his brother Einion. He was more reliant on his parents and had formed an alliance with his sister. Einion had done neither. Yet, one year on, both young ospreys share many similarities. Their migration down to Africa was uncannily similar, visiting the exact same areas en route several times, separated only by time.

Today they are both residing on the African Atlantic coast separated by just 300 miles. Just like his brother, Dulas has taught us much about osprey behaviour and migration in his first year. Whatever life has in store for him for his second year, we wish him well.

                                         Happy Birthday - Penblwydd Hapus Dulas

Andy Rouse's beautiful image of Dulas, shortly before he migrated - his sister Leri not far behind

Dulas has been in the same area for the last three months. He's still in the large estuary and river system on the Rio Cacine, Guinea-Bissau, just to the west of the Guinea border.

He arrived here on January 17th and has not moved out of his 11 mile radius home range in all that time. His environment will look a lot different now to what it did in January - most of the other ospreys that would have been competing with him for food and good perching spots will have disappeared. The only remaining ospreys will be birds of the same age as him, and a few which are a year older.

In less than two months Dulas will be a year old and will probably have caught in excess of 300 fish. We must not assume it's plain sailing from now on however, he's still in the throes of a severe dry season. Two other satellite tracked ospreys seem to have come to grief during the last few weeks unfortunately; Rutland Water's AW and Gill Lewis' Sky Hawk Ozwald. West Africa can be a hostile place for ospreys with much tougher conditions than back in the UK and elsewhere in Europe

Dulas' Mum and Dad have just arrived back at the Dyfi for another breeding season of course, but we will continue to keep a close eye on our tracked 2011 birds in Africa. Still nothing from Leri, but Einion seems to be doing well just like his brother.

Don't forget you can follow Dulas and Einion on Google Earth, their transmitters send back signals every two and three days respectively at the moment - help on how to do this can be found here.

Dulas seems to have settled down again. Having set off mid January, just a few hours before Janine and the Rutland guys got to Panchang in the Gambia where he had been since early October, he now seems to have set up home around 175 miles to the south of his old location in the southern Tombali region of Guinea-Bissau.

His coordinates and data were very late coming through this time for some reason and for a few hours the Satellite system had him in the middle of the Atlantic! It's only when all the data in a particular information window is in, that you can really refine it and put it through some sophisticated software; this in turn churns out all the way-points that you can see on Google Earth. Once that window is open however, you can ask the system for a 'last known location point' - a kind of short cut to save waiting for the data window (which can take up to 10 hours) to finish. The problem with this system however, is that the point it gives you is not necessarily that accurate. This is the way-point that it gave for three whole hours during the last window.

Thankfully, three hours later Dulas was back in Africa once all the information was in. Clearly a rogue data point. That will teach me to try and fast-track the system next time!.

Two weeks after Dulas decided to venture south he seems to have settled in the Cantanhez Forest National Park - a 400 square mile protected habitat which includes Chimpanzees as one of the mammals in the Park. Not many of them on the Dyfi when he left. The National park is around 15 miles inland off a large estuary and river system on the Rio Cacine, Guinea-Bissau.

This habitat looks ideal for ospreys with plenty of waterways that you would expect to be filled with fish. Dulas is in almost the exact same location as where one of Roy Dennis' ospreys 'Nimrod' overwinters. This is a bird that Roy ringed (Red 7J) as a chick in 2001 and subsequently satellite tagged in 2008, although at some point last summer the antenna of his tracker fell off, so now no data is sent but Roy sees him every summer as he returns to breed at his nest near Kinloss, Scotland. You can read more about Nimrod on Roy's website.

Nimrod - Red 7J. Photograph courtesy of David Whitaker ©

In previous blogs we speculated whether Dulas' location just north of the Gambia would start to dry up in the new year - maybe this has happened? The dry season in parts of west Africa is particularly arid this year. Hopefully Dulas has now found a good spot near the sea, like Einion has, that is not prone to drying up.

Our two boys have made it safely to their first new calendar year, and with a bit of luck, Leri will have too. An osprey's first winter in Africa is all about survival, if they can make it through to the first significant rains of the year they have a much better chance then of making it back to the UK the following spring. There is still some way to go, it will not rain in earnest until June, but there is something else to look forward to.

Around 90% of the ospreys in Senegal and Gambia right now will be two years old or more this year, which means that in two to three months they will all start their migrations north. Mature and established breeding ospreys will start their journeys as early as the middle of February onwards, younger non-breeding birds usually set off a little later. By April though, nine out of every ten ospreys will have gone, and gone for several months. As rivers and tributaries get drier and drier, at least the fierce competition for the better feeding areas will have almost disappeared.

Dulas has been extremely settled in this part of the Gambia since he arrived here at the end of September, wandering off for just a few days in November to see if the grass was any greener somewhere else. He is still not making many trips to the Gambia River itself despite the fact it is only four miles south of him - less than 10 minutes away. Is there too much competition here from adult birds? If there is, he has some good news coming his way in a few weeks.

There has been a little change in Dulas' movements however. He has not been to the area to the right of the map where the concentrated blue waypoints are since December 17th, slowly but surely moving slightly west. Is this area that served him well for his first 10 weeks in Gambia drying up? Frederic has already told us that many parts where we can see water on Google Earth maps have dried up.

It will be fascinating to see what Dulas does next, whether he will end up on the Gambia River itself in March as other ospreys magically disappear. Let's hope so, the river will see him through until the rains come again.

On November 15th Dulas headed off west from the area he had frequented for the previous seven weeks. In the last blog we theorised that his location at this tributary to the Gambia River had started to dry up, the rainy season is now well and truly over. As he reached the Atlantic coast Dulas headed south towards the Casamance River, Senegal, where there are ospreys galore. However he didn't even stop here, preferring to continue south towards Guinea-Bissau and by late afternoon on the following day, November 16th, he had reached Rio Cacheu - the country's northern most great river - see bottom of map.

The following day he was headed back up north towards Gambia again, clearly his Portuguese wasn't up to scratch to stay in Guinea-Bissau. By November 18th he was back on the River Gambia and by November 22nd, a week after he started his journey, he was back at the same tributary where he started off from. It looks like he was even roosting and perching on the exact same trees that he had been for the previous seven weeks!

His anti-clockwise trip took him a week to complete and he covered around 400 miles before ending up on the same tree as he started off from. Up to just very recently we had no idea that ospreys were taking these long journeys in their wintering grounds. We know from other satellite tagged ospreys during the last three or four years that it is normal for first-winter birds to make these kind of excursions, very often ending up in the exact same place as they started off from. Indeed, Einion has shown similar behaviour only he prefers the shorter, day-trip style vacation, his first over 500 miles!

Often, it is not until the following spring that first year ospreys start to settle down in earnest in one spot once the vast majority of full-adult birds have headed back to the UK for the breeding season. Ospreys don't usually return to the UK until they are at least two years old as they are not old enough to reproduce. It will be fascinating to follow both Dulas and his slightly less nomadic brother Einion over the next few weeks and months..
 

In last week's Dulas blog we mentioned the risk of the water system he was on drying up. Yesterday morning at 11.00 Dulas started to fly west from this area that he had been in for the last seven weeks - was this area actually drying up and making fishing difficult for him? We know that the rainy season this year has been particularly short which usually results in the bringing forward of the dry season to October and November. Here is the average rainfall for Gambia, the next significant rain is eight months away:

By 16.00 Dulas had reached the Atlantic coast having flown around 130 miles during the afternoon of November 15th following the Gambia River. If he would have turned right and flown north there's a good chance he would have encountered his brother Einion - he's only 90 miles up the coast. Instead he decided to turn south by Banjul and by late afternoon had just crossed the border from Gambia to Senegal.

This is the last GPS position we have for him - we won't get another download now for five days as his tracker transmission schedule changes to winter mode today - every five days now until March 14th. How frustrating! If he keeps going in this direction Dulas is only around 30 miles away from a huge river and mangrove area of south-west Senegal on the great Casamance River. It looks ideal habitat for ospreys - lets hope he makes it and continues south.

We have already learnt a lot from the satellite tracking data of Einion, Dulas and Leri. What is becoming clear from this research and other studies in the UK, is that young ospreys face huge challenges once they reach west Africa. It's not the 3,500 mile journey that seems to present the biggest danger but surviving once they get there. There is increased predation pressure for sure, as well as competition for good fishing areas from older, established ospreys.

Having concentrated on Leri recently, we shouldn't forget her two brothers of course. Dulas has been in the same area since September 29th, almost six weeks, on what looks like a marshy area just three miles north of the Gambia River, around 100 miles inland from the mouth of the great river.

Both Dulas and Einion seem to have found areas they are happy with. However, Dulas seems to be in habitat that could be prone to drying up over the winter months, will he start to move on if this area dries up? Looking at the map he has already made a few trips to the Gambia River itself  - why does he not stay here? Is he coming up against other full adult ospreys that have established themselves here for many years and is sent packing?

Just like dinosaur bones can only tell you so much about the animal, they can't tell you what colour they were for example, satellite trackers for all their benefits cannot tell you  exactly is happening where the osprey is and what the bird is doing. Neither can they tell you about the condition of the osprey or how many predators and other ospreys there are in the area. We hope of course that six weeks in the same area is good news - plenty of fish, getting in good condition after the migration and so on.

Roy Dennis and the BBC are on the Gambia River this week looking for Dulas and Einion - will they find them? Will they be strong healthy birds like we hope? We've not heard anything back yet so we honestly don't know. Roll on this Friday's Autumnwatch..

Another week and a half passes by and Dulas is still in the exact same region as he has been since arriving in the Gambia at the start of the month. He's familiarising himself with a tributary of the Gambia River around three miles north of the great river itself, and we've started to get multiple waypoints for him. This means that Dulas is starting to find favourite roosting and perching spots that he comes back to over several days.

We have no way of knowing what condition Dulas is in of course but we hope that due to the fact he has settled down on this two mile stretch of the river that he's happy where he is and catching enough fish. He has made a couple of trips onto the Gambia River itself though, as you can see below, but is there too much competition from other adult ospreys here for him to stay? Will his tributary to the north dry up over the winter months?

Dulas continues to spend his time around a tributary of the River Gambia to the north of the country. He has now been in this area for nearly a week, making a few short trips but not venturing further than an eight miles range. In the last few days he has developed a routine of roosting in trees near to a small gathering of houses, then heading out to the water and spending the daytime perched in the mangroves. It will be interesting to observe his movements in the next few weeks. He may have to move on if there is a food shortage or if he is chased away by other adult wintering ospreys, the latter being more likely. Still, he got plenty of abuse from Leri in the nest and lived to fight another day.

Unlike his brother Einion, Dulas has taken his time travelling over the Sahara desert finally arriving on the north Senegal border on the morning of September 27th. It is impossible to know for sure of course but Dulas has most likely gone several days without eating, maybe five days or more.

As soon as he reached the centre of Senegal he stopped for the night on the 27th and then immediately changed course the following morning, heading directly west in the direction of the Gambia River. How did he know to do that? He travelled less than 100 miles the following day after changing direction, he was probably still feeding himself up after his long desert journey.

By the evening of the 29th he was roosting on the northern border of the Gambia, just six miles north of the great river; 18 days earlier I took this photo of him on the Dyfi. Now he's seeing Hippos, Elephants and Chimpanzees for the first time.. just a little different from the animals he saw on the Dyfi two and a half weeks earlier!

Dulas calling for food (September 11th) the evening before he started his 17 day migration west Africa

On September 20^th, Dulas set off at first light, clearly he had no intention to stop like his brother. By lunchtime he had passed Marrakech and was soon over the Anti-Atlas Mountains, coming to rest after a day’s flight of 173 miles. On the 21st Dulas spent no time hanging around and was off in a SW direction. By mid-afternoon he was across the border into Algeria and stopped for the night NE of Tindouf, a day’s journey of 153 miles. 22nd - Flying in a SW direction he pressed on, passing through Western Sahara and covering 206 miles before roosting in Northern Mauritania. 23rd - No stopping him now, he covered another 291 miles flight down through Mauritania. 24th - Passing to the East of the Akchar desert Dulas had covered 90 miles by 2pm, the time of the last data received.

In 12 days of migration, Dulas was now 2651 miles from home. He was just 322 miles off the border of Senegal and more importantly, water. Will he have covered that distance in two days? We will find out tomorrow….

Despite being blown 300 miles east on the worst day of the storms last week on his first day of migration, Dulas has corrected for this well. By the time he had reached northern Spain he was only 60 miles east of where his brother Einion had been a few days earlier. By the time he passed Madrid, both he and Einion were in the exact same place separated only by time. Incredible.

The last coordinate we have for Dulas has him on the Guadiaro River, just 5 miles away from where Einion was on September 6th near Gibraltar. Amazingly, Roy Dennis was in this area last week and actually saw one of his tagged ospreys, Beatrice, in the very same place as Dulas is on the 18th - she over-winters here.  Both Dulas and Beatrice must have seen each other?

Thankfully, the wind turbine theory was right, Dulas had roosted on a circular balcony 10 meters up on one of the Gunfleet Sands turbines overnight. Phew.
He set off at first light the following morning, September 13th, briefly crossing the UK mainland between Ramsgate and Margate, before taking a short, 32 mile journey across the English Channel, hitting the French coast east of Calais just after 08.00 Tuesday morning.  He made good progress covering almost 170 miles before settling near Flavy-le-Meldeux in the early evening. The latest confirmed GPS reading for Dulas shows him approximately 40 miles north-east of Paris, at 10.00. Dulas started his migration at 14 weeks old exactly, 98 days, fairly late for an osprey.

Early morning on 12^th September, Dulas started his migration - he was 14 weeks old exactly. It was the day, however, we wished he hadn't gone, the follow up of Hurricane Katia was at it's strongest in the UK producing winds of 60mph in mid Wales. Subsequently, Dulas was blown east.

By 11.00 he was over Stratford-Upon-Avon; by 12.00, Towcester in Northamptonshire and by 13.00 he was over Flitwick in Bedfordshire. At 16.00 he was over the North Sea off the coast of Essex at which point he turned south spending the next few hours almost in the same position six miles to sea off Clacton on Sea. Has he succumb to the elements and is floating with the current? We think he may have roosted on one of the Gunfleet Sands wind turbines in that area as he is consistently showing an altitude of 10 meters. We won't know for sure until the next download on the 14^th. Fingers and everything crossed.

Here's a wind turbine at Gunfleet Sands - we think Dulas may have roosted 10m up on the balcony type structure