Over the Christmas period, I spent a rather gloomy few hours one afternoon down by the Leri River, the same river that our female chick was named after, of course, just around five miles west of the osprey nest. There were four Mute swans feeding on the river, three adults and a juvenile, and all but one were ringed with blue leg rings.
Juvenile Mute swan with a blue leg ring clearly showing
I know Tony Cross (of the Welsh Kite Trust) rings many species other than Kites, in fact, he ringed the Dyfi osprey chicks for us in 2011. After a quick email exchange with Tony, who was indeed the ringer of swans, the origins of the three ringed birds were known.
So, the adult female was ringed in exactly the same place on the Leri four months earlier in August. The adult male was ringed in Tywyn originally, around six miles north, and then ringed with the blue leg ring on the same day as the female on the Leri, August 17th. The juvenile was ringed as a cygnet six weeks later but in Welshpool, 40 miles away. Were these adults the parents of the juvenile? It would seem unlikely, despite the fact that Mute swans tend to stick around as a family for at least the first winter. Maybe the fourth unringed swan was a parent?
Whilst we have all been amazed at the data the satellite trackers have provided us over the last few months about our three ospreys, we shouldn't forget either that bird ringing is still going strong despite being over 100 years old, and continues to provide invaluable information about bird ecology. Our colleagues at Leicestershire and Rutland Wildlife Trust have been ringing all their osprey chicks since the first one hatched there 11 years ago. The RSPB have been doing the same at the Glaslyn osprey nest just up the road from the Dyfi. Here are some interesting results on return rates from the Glaslyn and Rutland nests up to and including 2009:
These figures are intriguing. Why are there double the amount of males seen returning as females? Do they have a higher survival rate? Is it because they are easier to spot as they tend to come back to the same areas as they were reared? Is it something else? It should be pointed out that these return rates are absolute minimum figures - there are probably more ospreys than this out there, either having not returned yet or have simply not been spotted.
We know this information purely from ringing - those colour rings are priceless when an osprey returns from Africa in his/her second or third year. They give us a great picture of osprey population dynamics and will continue to do so into the future. Here's a great example: Of the three osprey pairs that are known to have bred in Wales in modern times, one parent from each pair has come from the Rutland Osprey Project, including Nora, of course, who has a White 03 ring. The Glaslyn male was ringed Orange 11 (but has now lost this ring during the winter 06/07) and the male from the successful breeding pair near Welshpool in 2004 had a ring White 07 (1997). The female from this nest was also ringed, she was a Scottish (Perthshire) bird with a leg ring Red 6J (2001). Rutland is on the same latitude as Dyfi/Glaslyn, around 52° North. Are returning adult ospreys genetically predisposed to stop once they reach their natal latitude? There is evidence here to suggest that they are.
All this hard work by the ringers is paying off, and there is more good news. We are seeing more ospreys year after year. More at Rutland, more at Glaslyn and certainly more on the Dyfi - we must have seen at least 10 adult ospreys this year either try and land on the Dyfi nest or come very close. In fact, one of them was a three-year-old Glaslyn male osprey born in 2008, with a ring White YC. Here's a short video of him from this summer getting too close to Nora and her eggs!
After centuries of persecution the future for ospreys now looks decidedly better. As I left the River Leri last week, it dawned on me the connection between the swans and ospreys. Both Leri and the swans were ringed with blue leg rings this year, the swans bred on the Leri and the osprey was named after the Leri! As I got into the car with the light fading, this Short Eared Owl below was foraging in the gloom either side of the River Leri, a species which has had its own problems of late. Did he have a blue leg ring? No he didn't - now that would have been a spooky coincidence!
The Montgomeryshire Wildlife Trust would like to thank all of you for your support in 2011, it has been some year. Come March and April keep an eye out for these ringed ospreys returning, they could well turn up somewhere near you.
A Happy New Year to you all. Blwyddyn Newydd Dda i chi gyd.
