I spent an interesting and pleasurable few hours in the company of John Williams yesterday - a ranger and Egg Watch warden at Dai Dot's nest, around 12 miles from the Dyfi. We call this nest ON5 (Osprey Nest 5) - it is the fifth osprey nest in Wales in modern times after Welshpool (2004 only), Glaslyn, Dyfi and ON4 in Snowdonia.

John works for Natural Resources Wales and he and I have worked closely together since Dai started breeding on this nest in 2014. To date, Dai has produced five fledglings with another unringed osprey named Delyth; two in 2014 and three in 2015.

Dai Dot - so called due to his two white plumage 'dots' above his beak

To say that the start of the 2016 season has been a touch confusing would be an understatement to say the least.

Both Dai and Delyth were back at ON5 by 25th March and by around two weeks later both birds were seen incubating. However, things were not that simple - Dai was recorded several times at the Dyfi when there were two ospreys at ON5. Both nests are only 20 - 30 minutes flying time apart, so it was not always easy to try to cross reference, particularly when mobile phone signals are weak to non-existent at ON5. It didn't help either that both Blue 24 had also been spotted at ON5 a few times as well as probably Blue 5F.

I'm pretty certain now however, after looking at all the times and observations from John, that indeed it has been Dai Dot at ON5 and they were his eggs. A brief visit to the Dyfi nest on 31st March correlated well with an absence window at ON5, so clearly Dai has been making quick visits to the Dyfi and possibly to other nests. This is completely normal behaviour for male ospreys, even when they are breeding themselves.

So fast-forward to this week and John is telling me that Dai hasn't been seen at ON5 since last Friday (22nd April), but there has been another male on the nest with Delyth. No incubation activities have been recorded either.

Here is a photo I took of the male at ON5 yesterday afternoon. It is clearly not Dai Dot.

This new male has a particularly white underwing pattern and completely different head-plumage to Dai. He is unringed.

This male brought a fish back to Delyth when I was there, he was mating with her and was periodically scraping out an egg cup in the nest. Neither osprey incubated. So what is going on?

Delyth food soliciting to her new male 27th April 2016, she was not incubating

Displacement

Dai Dot has clearly been displaced from the ON5 nest as the breeding male. The eggs are either still in there, or, much more likely, been chucked out by the new male (from afar, the actions of scraping out an egg cup look exactly like the movements of an osprey kicking eggs out). A male osprey that takes over at a new nest during the incubation period will always kick the eggs of his predecessor out if he thinks they are not his.

Where this new male has come from we don't know, he is not ringed. Has he been spotted anywhere else before ON5? We're looking through various photographs, but here is a clear candidate - a very white-winged male osprey that landed briefly on the Glaslyn nest on 7th April.

Glaslyn nest - is this the same bird (right) that is now on ON5

So the BIG question then, why has Dai been ousted from his established breeding nest at ON5?

We think Dai is relatively young, maybe a 2007 - 2009 bird. We know he's got two good breeding years under his belt at ON5, producing five fledglings with Delyth in two years - he should be extremely difficult to displace, but he has been. We have three theories:

1. He's Dead

I went straight from ON5 yesterday to Cors Dyfi to do some filming of Blue 24 (more on this in tomorrow's blog). And who happens to turn up at 19:31? Dai Dot!

Dai Dot flies straight over Blue 24's nest in the evening sunshine

He also came close to landing on Glesni and Monty's nest - here he comes..

So that rules this theory out - thankfully Dai is very much alive.

2. Useless Male Theory

Some ospreys just seem to be a bit, well, useless.

Not providing enough food, not incubating enough, not defending a breeding nest from intrusions... the list goes on. We have to be careful though don't we.. what we think a male osprey should behave like is a very human perspective and we probably shouldn't use the term 'useless male' either in all honesty.

Orange VS springs to mind at Loch Garten a few years ago. A lovely male osprey looking for a nest to breed at, and when he finally got his chance, he flunked it. One of the chicks starved to death while the female of the nest (EJ) tried desperately to fish for the family. Another male, Blue 28(2010), also has a history of being displaced from his Rutland nest (by his brother!).

Does Dai fall into this useless male category? Probably not - he looked in fine form in 2014 and 2015 producing five strong chicks to migration age.

3. Injured Bird Theory

If Dai has an injury of some sorts, this would weaken him and make him more susceptible to a takeover attempt. But does he have an injury and how would we know?

Seconds after the above photo of Dai was taken, he made a quick right turn and we could clearly see some kind of a blood stain and/or injury under his right wing.

It's common to see blood on birds of prey, including ospreys, but it's generally found on their faces, chests, legs and feet - the blood coming from their prey, not themselves.

We have half a dozen other images that show this blood stain and possibly some feather realignment too. We can't be sure and have to stress this is only a possibility, a theory, but it would certainly explain why Dai was seemingly so easily ousted from his breeding territory.

Did Dai arrive back from migration with this injury or did he sustain it defending his nest from the newcomer?

If Dai does have an injury he seemed to be able to fly around the Dyfi unrestricted yesterday evening - let's hope that it's nothing serious and the worst outcome for Dai is that he has lost his breeding nest. And all this begs another question of course - would Dai Dot settle with Blue 24 on her nest or would Monty escort him away like he did last night in the video above?

We'll keep a look out for him and will, of course, keep you posted.