Posted: Friday 1st July 2016 by Emyr MWT
We took advantage of a break in the weather yesterday to ring both our osprey chicks.
With the North Atlantic Jetstream unseasonably low (south) resulting in high winds and heavy rain in the UK, more care than usual was needed this year to pick out a window where the tides are sufficiently low and we get a lull in-between weather fronts.
We also had a bit more to think about in 2016 regarding exactly what we needed to do once we get to the nest, with causing as little disturbance as possible always being the main priority. We'd received permission to remove the unhatched egg as well as to take buccal (saliva) swabs from each chick. We also needed to clean the cameras while ringers Tony and Chris got on with the ringing itself at the bottom of the nest, as well as remove part of a plastic black bin liner that had lodged itself in the nest for the last few weeks.
Thankfully, everything went without a hitch.
The first thing we noticed as soon as we lowered both chicks to the ground was the massive size difference between each bird.
Little and Large
The above image is in chronological order - the chick on the left hatched first from the first egg, then the second egg which remained unhatched, followed by the third chick from the third egg on the right. The difference between both chicks hatching is 4½ days so we expected a developmental stagger, but this was very noticeable - much more apparent than we could see on the nest cameras.
Chick 1 weighed 1,689g while chick 2 came in at 1,343g. So the first chick was over 25% heavier than its sibling - much more than you would expect from a 4½ day age difference. It was very clear right from the outset we had one of each. Chick 1 is a female and chick 2 a male.
Oh, please; not more scales...
These were some of the most passive and serene osprey chicks I have seen. The calls from the circling adults command the chicks to 'play dead' - a type of behavioural mimicry (thanatosis) that will serve the flightless chicks well in a situation where a real predator is present. Laying dead-still in the nest gives the birds a high degree of camouflage and their greatest level of survival advantage if the parents are unable to defend them. Paradoxically, it helps us to ring them in the shortest time possible, allowing us to get them back to the nest quickly - they make no behavioural distinction between an approaching goshawk or a couple of friendly ringers. Thanatosis is a wonderful thing!
Both chicks were out and back in their nest in 38 minutes.
Here is the video of yesterday's ringing (it's in 4K resolution - choose your own resolution for your screen/bandwidth):
Music: Grow by Frances
So we have one of each:
Chick 1 is a female: Blue Z0 - Ceri
Chick 2 is a male: Blue Z1 - Tegid
You may remember the Posh Pete Test? Every year we name our chicks after Welsh rivers and lakes and we test the pronunciations out on volunteer Posh Pete, whose command of the Welsh language is, well, not the best!
Pete has not been well recently but is on the mend. Thankfully, these three lovely ladies stood in for him yesterday, so if you would like to know how we got to Ceri and Tegid, and would like to know how to pronounce them, this video is for you...
We've sent the unhatched egg to Dr. Nicola Hemmings at Sheffield University. Nicola is an expert in analysing unhatched eggs - have a look here at some of her work with an unhatched peregrine egg last year - fascinating stuff.
The saliva swabs will be analysed by geneticist Dr. Matt Hegarty at Aberystwyth University - much more on this in a future article on this website.
A huge thank-you as usual to Tony Cross for ringing our ospreys for us and fellow ringer Dr. Chris Townsend who is currently the President of Montgomeryshire Wildlife Trust. Thanks also to Al Davies for all his help again this year by making everybody else's life that much easier on ringing day.
It's ironic isn't it.. we dedicate our lives to protecting these eggs and birds, we shield them from harm, yet, for 38 minutes yesterday, we intruded into their lives for a little over half an hour. They're not to know it of course, but we are there to help them and their species.
This will hopefully be their only ever close contact with humans throughout their long and productive lives. We know a bit more about these two Welsh ospreys than we did this time yesterday and we've two more reasons to be looking skywards from May 2018 onwards.
Ceri - Nature's most beautiful