UV researches Kielder in depth

Before covering the events of 19 July…  most readers will know our Nest 1A and Nest 2 males, White YA and Yellow 37, hatched at Glaslyn in North Wales. Their half sister, Blue W7, has a problem with her right foot. We send our very, very best wishes to Glaslyn for her recovery.

UV has visited Kielder a few times now. On 19 July he spent most of the day here and there were one minute fixes for some of the time. He was at or near all four nests so for nest protection images are limited, but we gained great insight into his activity from such detailed data. Paul has written this blog, an important piece of analysis which is almost certainly a first for the UK. Over to Paul:-

Visits to active nests by non-breeding individuals are an integral part of osprey ecology. We use the word “intrusions” for these incidents, which implies some kind of hostile intent on the part of the intruder. In fact, this whole aspect of their behaviour is much more subtle and complicated than mere aggression.

A typical intruder incident (c) Forestry Commission England

A typical intruder incident
(c) Forestry Commission England

It’s true that some ospreys may attempt to take over a nest site occupied by another pair. Such a case will often result in talon-to-talon combat – and yet the takeover attempt itself is far more often unsuccessful than not. Evolutionary theory tells us that the risk of physical injury or even death would hardly be worth it, when the attacker’s statistical chances of obtaining a breeding site are so low.

In fact, the vast majority of active nest intrusions have no aggressive agenda. To use a (slightly weak) military analogy, they are not offensive manoeuvres but more like intelligence-gathering missions. Young non-breeding ospreys can gather a great deal of crucial information by visiting a successful nest and the area around it. The fact that an active nest is present at all, tells the visitor that he or she is in a “good place” for ospreys. If the nest is large and well-formed, it means that there is plenty of construction material nearby. A brood of healthy well-grown chicks signify adequate food supplies.

Since the installation by Forestry Commission England of nest monitoring cameras and video recording equipment at Kielder, we have seen many such nest intrusions at all stages of the osprey breeding season. But – for obvious reasons – all of these observations are seen from the nesting birds’ “point of view”. We can’t really know what the intruder is doing during the period immediately before and after its fleeting appearance on screen.

But on the 19th of July 2016, Blue UV changed all that…

He had visited his home area before but, on this occasion, good weather (very rare during this summer of near-permanent overcast) meant that he could return for some serious nest-visiting. His detailed tracking data allowed us to visualise – perhaps for the first time in UK osprey studies – the way an intruding osprey behaves during these events.

To avoid giving away the locations of protected nesting sites, this blog will have to do without most of the usual fancy graphics and animations. (All times in the text are in UTC unless otherwise stated, the nestcam times are BST ie 1 hour ahead.)

Reconnaissance, Nest 2

UV left his roost site in eastern Cumbria just after 08:30 and by 10:20 was over the boundary of the park and heading towards Nest 2. On arrival, he positions himself by flying along a ridge line above and to the north of the nest, about 500m away. He is observing the nest, and what is going on there.

At 10:39, UV decides that a closer approach is possible and heads straight for the nest. He makes one pass over it at a height of about 70m, then veers away, chased by another bird – probably Uncle 37!

UV overhead! (c) Forestry Commission England

UV overhead!
(c) Forestry Commission England

UV is being chased away (c) Forestry Commission England

UV is being chased away, upper right
(c) Forestry Commission England

UV continues towards Nest 3, arriving there around 11:10.

Reconnaissance, Nest 3

UV adopts a similar tactic at Nest 3, favouring the higher ground behind the nest platform but this time keeping an average distance of around 350m. He remains in the area for only 10 minutes.

Interlude – local exploration

After this, UV flies a long semi-circular loop around the northern sector of the forest – a path which eventually brings him back towards Nest 2 at 12:10.

Intrusion, Nest 2

Again, UV stands off at a distance of some 500-600m for 2 minutes, and then makes a direct pass over the nest at 12:14.

EB sees UV approaching (c) Forestry Commission England

EB sees UV approaching
(c) Forestry Commission England

This time he is much lower – only about 20-30m above the platform height. Immediately after this, he flies 750m back up to the ridge line, and perches in a tree for the next ten minutes. His next batch of points show a zig-zag path away from the nest area. We interpret all this as UV being chased away by one of the nesting adults.

Nest 2 again

At 13:13, UV makes another close approach at Nest 2.

EB sees UV arriving (c) Forestry Commission England

EB sees UV arriving
(c) Forestry Commission England

He wheels away, and comes in again (13:22) for second pass. His speeds in these manoeuvres are fairly high, 25-30 knots. (45-55 kph). Again, he returns to the ridge line and perches, this time for 15 minutes. At 13:53, another low-level pass at the nest. Immediately after this, he leaves the area and perches some distance away to the south- east.

This image, with UV’s overall track shown FROM BELOW, shows the pattern of movements associated with a series of nest intrusions and subsequent chases.

UV around a nest site Courtesy Paul Widlifewriter

UV around a nest site
Courtesy Paul Widlifewriter


Back to Nest 3, but not for long

After another leisurely tour of the forest with several perching stops, UV arrives again at Nest 3 (15:27). This nest does not seem to interest him quite as much as Nest 2: he spends a few minutes watching it from the same range as before (350m) before flying away northwards gaining altitude on the way.

By 15:40 he has made a detour towards high fell overlooking his parental nests at Nest 1 / Nest 1A. However, they are over 1000m distant and he does not approach any closer than this. Instead, he backtracks along his previous path. UV has not done with Nest 2 yet…

Nest 2 Intrusion #4

UV arrives back at the ridge overlooking Nest 2 by 16:29. Unlike his previous visits, he doesn’t fly along it but makes another direct pass by the nest (16:30), turning back sharply and gaining height to over 700m. There is video evidence that he was intercepted again during this pass. Here is a screengrab of EB taking off after UV.

EB leaves to chase UV away (c) Forestry Commission England

EB leaves to chase UV away
(c) Forestry Commission England

Still climbing (1000m+) he alters course to the west and flies out of the Park in the direction of Newcastleton.


A striking aspect of the day’s activities is the amount of ground covered by UV within the boundaries of Kielder Forest, and the frequent and pronounced altitude changes during it.

Time under discussion highlighted courtesy Paul Wildlifewriter

Time under discussion highlighted
courtesy Paul Wildlifewriter

This kind of flying must consume a great deal of energy, UV flew 130 km around Kielder – much more than normal daily foraging and flights to and from roost sites. The whole behaviour of nest-visiting and intrusions must have a considerable benefit for it to have evolved in the face of such an energy budget.

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Double session of Motor Boat Cruises, a special event!

The Calvert Trust had a big booking for their Motor Boat Cruise yesterday, twice the two boats’ capacity. Rising to the challenge a double session was arranged, 16.00-18.00 and the usual 18.00-20.00. NWT volunteer Margaret did a double shift, here is her account:-

An exceptional evening in many respects with 30 booked for the trips. All were staying in Bellingham for the wedding, this Saturday, of Natasha and Richard. Dave and Pat were our boatmen for both trips with Joanna and I as the volunteers for the 4pm trips and Glynis and I for the 6pm ones.

On the first outing we had several good sightings with Natasha particularly keen to learn as much as possible about osprey. The sand martins also put on a good display but the highlight was seeing two osprey at the same time as we came back to Wickhope. They were close enough to get good sightings without binoculars and stayed long enough for the guests to watch from the jetty at the end of their trip.

Unfortunately the two osprey did not stay around for the arrival of the second group but not long after we set off again two deer were seen on the north shore by Pat’s boat who radioed the sighting to us. We edged the boats closer to the shore and everyone was able to see at least one of the deer. For one of the Australians in the party this was the highlight of the trip having seen osprey on many previous occasions. We soon had our first sighting of the osprey, followed by several more, with Dave and a couple of the guests particularly good a spotting the birds. Around 6.50 Dave spotted a bird dive for fish, and we all watched it struggle to get airborne with a large wriggling fish. After around 10 minutes it eventually reached tree height and initially looked as if it was heading for Nest 1A but then headed off out of sight towards the dam. We felt privileged to have witnessed such a sight but there was more to come. A cormorant and a mallard did fly pasts and then as we headed back to Wickhope another osprey came into view and caught a fish! We had good views of the bird and its fish as it flew closer before heading off with its catch – as I say an exceptional evening – what more could we ask?


What a great evening for the wedding party! Neither of the two catches seen on the second cruise were YA – the first cruise possibly saw him hunting from a distance. Here he is escaping from the frenzy at the nest!

YA escapes! (c) Forestry Commission England

YA escapes!
(c) Forestry Commission England

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Nest 2 fledging complete and news from Nests 1A and 3

Nest 2

Field monitoring of Nest 2 has confirmed that Y6 has fledged although the date isn’t known. All three juveniles were flying around the clear fell surrounding the nest site this morning. EB was ‘supervising’ alone – maybe 37 was away towards the Solway Firth catching a flounder! He brought in a trout from the reservoir during inconclusive monitoring on Tuesday. So we have a new record for Kielder with nine juveniles already fledged and the pair on Nest 4 a week or so away from that momentous event.

Nest 1A

Y0 has still not been seen, nor any evidence found of what may have happened to her. But her three siblings on Nest 1A are doing very well. Through the scopes visitors to Osprey Watch have been enjoying watching them flying. They’ve been laughing at their activity on the nest as seen via the nestcam at either the Osprey Cabin at Leaplish Waterside Park or in Kielder Castle Cafe.

Yesterday’s Osprey Watch Report gives a flavour:-

A bright if breezy day welcomed us today, and before we had a chance to set up the first visitors arrived, and the pattern was set for the rest of the day, with a constant stream keeping us busy. A lot of people had been to see Osprey at other sites in Scotland and Rutlland and had a good knowledge, others had just stumbled upon us while on holiday but nevertheless were just as enthusiastic. One family had been there all of Tuesday monitoring the nest and reading all of the information on site and by today were quite experts on all things Osprey!

On arrival today Mrs YA was finishing off the remains of a Trout with Y3, who were on the nest for most of the morning with Y1 having his share and Y2 making a brief visit.

Y1 takes over from Y3 (c) Forestry Commission England

Y1 takes over from Y3 who has flown
(c) Forestry Commission England

Then for about an hour at lunch time the nest was empty. When we were thinking about putting a recording on the screen we were saved by the return of Mrs YA, Y2 and Y3. During the afternoon they were joined at differing times by Y1 and YA and the windy conditions provided some spectacular views through the scopes of Ospreys trying to land successfully on the nest at the same time. (Press the HD button for best quality on a short video of some juvenile action.)

Late afternoon and no sign of a fish had a couple of the young calling to be fed, but were disappointed when first Mrs YA landed with moss and then YA with a large twig.

We estimated we received in excess of 140 visitors with the good weather and school holidays contributing to an eventful day.

Dave and Ian

The juveniles had to wait until 18.37 for a fish and then Y2 and Y3 had a prolonged struggle for possession. This is just part of the battle which was won by Y2.

He then ate for an hour. During this time YA landed with another fish which Y3 snatched before recently landed Y1 could get his talons into full action.

Y1 And Y3 fight it out (c) Forestry Commission England

Y1 And Y3 fight it out
(c) Forestry Commission England

Nest 3

The last few days have been uneventful if the limited recordings are representative. Quite often the nest is empty although the juveniles have been flying round the area. As is usually the case they are still eating on the nest and sometimes an adult feeds the juvenile despite their competence at DiY feeding!

VR eating whilst VH waits (c) Forestry Commission England

VR eating whilst VH waits
(c) Forestry Commission England

the female feeds VR (c) Forestry Commission England

the female feeds VR
(c) Forestry Commission England




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Intrusions galore!

As reported yesterday Blue AS6 – the new female breeding with White SS at Tweed Valley Osprey Project‘s televised nest – landed on Nest 1A.

AS6 drops in (c) Forestry Commisison England

AS6 drops in
(c) Forestry Commisison England

She was only on the nest a moment – this is the event. If you look well beyond the nest you can pick out YA in a favourite tree, his white chest gleaming. He flies to the right just before AS6 appears. Press HD for best quality.

She may still have been at Kielder shortly after 17.00.

Is this AS6 again? (c) Forestry Commission England

Is this AS6 again?
(c) Forestry Commission England

The Project Officer at Tweed Valley has told us that AS6 was still at her nest shortly before noon so her visit to Kielder was a Sunday afternoon jaunt. She is present at her nest with SS today.

Today there were 7 intrusion incidents on Nest 1A in a couple of hours, but in them all the intruder was too far away to identify. The juveniles, especially Y1, are stout defenders of their nest!

Y1 takes his eldest son responsibility seriously (c) Forestry Commission England

Y1 takes his eldest son responsibility seriously
(c) Forestry Commission England

The nearest the intruder(s) came was at 09.45.

Soon after midday an osprey flew close to the nest but the juveniles’ behviour indicated it was YA.

We have no audio so the different vocalisations can’t be distinguished. You can see the juveniles shouted but there was no mantling behaviour – their usual reaction now when they see a parent arriving – and the calls would have sounded different to those directed at an intruder.

The youngsters are ever hopeful of more food. When Mrs YA landed with some moss she had a frosty welcome from Y2.

Y2 wants fish not moss (c) Forestry Commission Engkand

Y2 wants fish not moss
(c) Forestry Commission England

Finally, yet another intruder!

N1A 15.46 GSW juvenile

A juvenile Great Spotted Woodpecker (c) Forestry Commission England

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A Scottish visitor

Just before 16.00 today an intruder landed on an empty Nest 1A.  She was hotly pursued by Mrs YA and then YA. She’s been at Kielder before.

Blue AS6 on a flying visit (c) Forestry Commission England

Blue AS6 on a flying visit
(c) Forestry Commission England

Blue AS6, a 2013 hatched female from near Muir of Ord, bred with the longstanding male at Tweed Valley but sadly one egg didn’t hatch and their chick died young. The pair had continued bonding. It isn’t clear if this is her heading south. Tweed Valley have been informed.

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Osprey Watch Report: 23 July and other news

Here’s the Report from yesterday’s very busy Osprey Watch:-

On arrival at 09.40ish 3 chicks were visible on the nest. Even before the scopes were all set up a couple arrived with their own scope. They were from the Netherlands and had already been to the Farne Isles, Bass Rock and Loch Lomond. Today was their last day in the UK before heading home on the ferry.

More visitors arrived, many of them from the NE. Around 11 am an osprey came over the water towards us circling high and gradually heading off towards Kielder.

We were not the only attraction at Leaplish – it was a family fun day with lots of activities. Our visitor numbers increased rapidly with nearly as many children as adults. Families were coming to us after they had taken part in the other activities with lots of the children proudly sporting medals and carrying cups. Several wooden osprey were assembled by children while their parents/carers watched the live stream and chatted about osprey. Many saw the 2.30 fish delivery being eaten, first by Y3 then by her brothers who had quite a tussle over what was left.

The battle for possession just after delivery! (c) Forestry Commission England

The battle for possession just after delivery!
(c) Forestry Commission England

A really great, if tiring, day with one or more birds on the nest for much of the day, no technical problems, hardly any midges, no rain, good views through the scopes including birds sitting in the tree to the right of the nest, lots of children, lots of dogs and at least 224 visitors!

Margaret, David and Alex

Well before Osprey Watch started Y3 showed she need to hone her landing skills a bit. Press the HD button on all the videos for best quality.

On  Friday there were a couple of intrusions by the same unringed osprey. The juveniles defended their nest with gusto!

Blue Y0

Sadly there is still no sign of Blue Y0, missing since fledging before 08.00 on 15 July. The adults are taking fish away from Nest 1A but that is normal behaviour at this stage – a quiet branch to enjoy a bite is preferable to a nest full of shouting juveniles.

Nest 1 footage is being checked in case she has visited there, although where to land is the question!

The Nest 1 garden (c) Forestry Commission England

The Nest 1 garden in the sky
(c) Forestry Commission England

Nest 2

At Nest 2 field observations on Saturday afternoon confirmed the safe fledges of Y4 and Y5. There was no evidence that Y6 has flown yet. That brings the total fledges to eight, the same as in 2014, the previous ‘best year’.

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Successful fledging at Nest 3!

The last post on Nest 3 reported that young male Blue VR was looking keen to fledge on 17 July. Within about 4 hours of watching him helicoptering in gusty winds he had flown for the first time. In the 15.00 clip only sister Blue VH is on the nest, guarding her meal!

VR is not to be seen (c) Forestry Commission England

VR is not to be seen
(c) Forestry Commission England

VH did some modest exercise that day. Press HD for best quality on the videos.

She probably didn’t fledge until the afternoon or early evening of 18 July. In footage at 17.00 she was pondering on the nest edge.

Is VH still thinking about fledging or perhaps another flight is on her mind (c) Forestry Commission England

Is VH still thinking about fledging? Or perhaps another flight is on her mind
(c) Forestry Commission England

She had definitely fledged by the evening.

The recording shut down soon after that flight but this is probably VH flying back towards the nest.

Probably VH returning (c) Forestry Commission England

Probably VH returning
(c) Forestry Commission England

Since then the recordings haven’t shown much activity. Eating is still important!

VH feeds whilst VR watches the world outside the nest (c) Forestry Commission England

VH feeds whilst VR watches the world outside the nest
(c) Forestry Commission England

Today VH was eating again, alone initially, but then VR arrived.

He wasn’t on the nest long.

VR goes for another trip around the area (c) Forestry Commission England

VR goes for another trip around the area
(c) Forestry Commission England

Now the pair have several weeks to hone their flight skills and increase their reserves by feeding on the nutritious Rainbow Trout before they embark on their first migration.

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