Posted: Thursday 19th May 2016 by Emyr MWT

 

Over on our Facebook page we have been discussing intruding ospreys this week and how we try to identify birds as individuals.

Over 95% of all intruders we see at the Dyfi are never identified - even if they are ringed and get pretty close like this bird in the video below taken last week.

 

 

Many times we don't actually see the intruder, it's Glesni's or Monty's alarm calling that give a bird's presence away (ospreys have a very distinctive call that they only use for other ospreys getting too close to them).

Around 50 - 60% of Scottish ospreys are not ringed, so, if we can work out that a bird is un-ringed, we assume Scottish (but not always!).

If a bird has a Darvic ring on the right leg, it's a Welsh or English bird and almost all these birds are ringed. Darvics go on the left leg in Scotland.


We also employ little behavioural tricks to try and work out who is who as well as looking for anatomical features such as missing (moulting) feathers. Have a look at the image below - Clarach on the Glaslyn nest on 14th May and a similar looking female at Rutland Water's Manton Bay nest three days later. Both birds missing secondary feather(s) in the same location on the right wing.


From what we can see of the head pattern on the Rutland photo (fairly pale plumage) and chest band - they are consistent with those features that we saw on Clarach as an adult at the Glaslyn nest last weekend. The missing secondary feathers raises the probability that it is her, quite significantly.

Here is the video that Kayleigh posted of the Manton Bay intruder in her blog yesterday:

 

Now enter the Live Chat on this website. JulieD and others (serial and professional osprey Live Streaming addicts!) actually saw the above bird land on the nest and were pretty convinced this intruder had a blue Darvic ring, right leg, with what looked like 2R, which is Clarach.

 

Jigsaw

And finally the last piece of the jigsaw. Tony and Monica Shooter were photographing ospreys at Manton Bay when all this happened and emailed me last night with these photos - it's Clarach!

 

 

 

Here's what they said: "As one of the birds came nearer the nest it stopped to hover overhead looking down at the chicks - Maya had moved to one side mantling and shouting up to the intruder. The bird came down and landed on the side of the nest, we have read her ring...it was 2R - Clarach! She stood on the nest looking at Maya and the chicks for about a minute before Maya briefly flew up to make her go off. Clarach flew round but came back onto the nest again this time it was only a few seconds before Maya again flew at her."


 

We are so pleased that Clarach has made her way to Rutland Water, not that we don't want ospreys in Wales of course, but simply due to the fact we have a distinct lack of males here at the moment (they will come) and already two polygamous arrangements on platforms that are too close to primary nests, which is no good for anyone.

And anyway - I think we owe Rutland a bird or two after stealing a few of theirs over the years! Clarach is back where her mother comes from and many of her relatives are still there - will she pop over to see Granny (Green 5N(04)) I wonder?

 

Q. How did Clarach find her way so quickly to Rutland ater after being at the Glaslyn, 145 miles away,  just a day or two before?

A. She almost certainly visited in 2015 as a two-year-old, prospecting for nest sites and mates.

 

I mentioned in the Clarach: Part II blog on Monday how working in partnerships with other organisations helps all of us learn more about ospreys and helps us better look after them. We've been working with Tim MacKrill and John Wright at our sister wildlife trust, Leicestershire & Rutland Wildlife Trust for over a decade now, and how wonderful we are able to work closely again with them, but this time on a bird heading east, not west! So, many thanks to Tim, John and Kayleigh at Rutland Water and also to Tony and Monica for sending us the images of Clarach from Manton Bay.

Tim thinks that there is "every chance' Clarach may find a male and pair up at Rutland water - let's hope so. Fantastic news.

 

Clarach (foreground) as a chick on the Dyfi nest - July 2013

Read Emyr MWT's latest blog entries.