Ringing the Chicks

On Weds 27th May 2020 the two Sheffield Peregrine chicks were ringed, measured and checked over by a team of experienced and licensed bird ringers.  The team made the precarious journey up the narrow winding steps and vertiginous ladder inside the church tower before emerging onto the roof and using climbing equipment step over the parapet to collect the chicks from the nest.


I am happy to report that both chicks look fit and well and are developing nicely.  They seem so much bigger in the flesh than they do on the webcam and also look much stronger and far less vulnerable.  It’s hard to believe they are not quite 3 weeks old yet!   The chicks were bright eyed, well behaved and occasionally vocal but not alarmingly so.  You can already see their primary  feathers coming through on trailing edges of their wings.  As you can see from the image below the black tips are already showing although most of the feather is still in its waxy protective sheath.


The birds are checked over and, as stated, look in good, normal health.  Ringers Amy and Dean who handled each bird could feel that they had full crops and bellies – they fed on Pigeon and Starling the day before so that’s not surprising!  The parents are feeding them well, and with only two mouths competing at mealtimes there’s obviously plenty to go round.



As well as confirming the chicks are healthy the purpose of ringing the chicks is to monitor survival rates and collect information about their movements.  Standard ringing tells us information if the bird is re-trapped (in mist nets for example) or if the bird is found dead.  This is fine for small birds which can be readily trapped and tracked during their lives but that’s bot so easy with birds of prey!  This is particularly pertinent to the Sheffield Peregrines: despite both of our adult birds wearing a standard silver BTO ring, nobody has ever obtained a close and clear enough image to read a number.  Therefore we know nothing about where they came from or how old they are.  This is where the more recent technique of colour rings comes in.


Today the Sheffield chicks have each been given a standard silver ring (or band as they are called in many other countries.)  Additionally they have been given large colour ring (also known as a darvic ring.)  These bright orange rings have a large 3 letter code which is much easier to read through binoculars or on photographs.  These big bright rings have been used on many birds of prey, perhaps most notably on Ospreys.  It enables birds to be more easily tracked, by multiple observers (any birder with binoculars or a camera not just scientists or trained ringers) throughout their lives, throughout their range and without the need for recapture.  Or death.  On Peregrines here in the north of England darvic rings have allowed us to learn that a 2018 Sheffield youngster (colour ring PSA) spent some of its first winter time in the Dearne Valley and the orange darvic ring “PRF”  identified a dead Peregrine found last year on a Sheffield City Centre roof as one of our 2017 offspring.  Sadly, just this last week, a darvic ring helped to identify an illegally killed Peregrine (found suspected shot in Brighouse) as one born at Leeds University in 2018.  More details on that here


As you can see from the photo our two chicks can now be identified as TRF and TNF.  TRF carries the BTO silver ring GV53849 and TNF carries the ring GV53850.


Various metrics were taken.  The birds had identical wings lengths of 147mm and both are very similar weights coming in just under 600g.  The length, width & depth of the Tarsus is measured* as is the length of the Hind Claw, the middle toe and the distance from the Bill to Cere.  From the information gathered TNF is ever so slightly bigger on 5 of the eight measurements but there’s not much in it.

* the Tarsometatarsus is a bone only found in the lower leg of birds, it’s a fusion of bones which is, in layman terms, equivalent to out ankle and foot (metatarsal) bones.  The easiest way to remember it is that it’s the part of the birds body which the rings go around  – i.e. the part often mistakenly identified as the bird’s leg.


The burning question on many lips is of course ‘What sex are the birds?’  Unfortunately we are unable to answer that questions currently from the metrics taken.  There’s no notable size difference so we can’t make any “guesstimates” that one is female and the other is male.  It’s a distinct possibility that both these Eyases are the same sex.  Due to not having chicks to ring in 2019 the last comparable data is the 3 chicks ringed in 2018.  The measurements that year showed one bird with significantly bigger measurements than the other two which led to an assumption that at least one of the birds was a female.  The three 2018 birds weighed 517, 581 and 620 grams was meaning there over 100g difference between the biggest and smallest bird.  There’s nothing so obvious this year as the birds weigh 584g (TRF) and 598g (TNF).  We cannot compare the birds between the years as the 2020 birds have been measured a couple of days later (Covid-19 related) than 2018 and of course the fact that there’s only 2 of them could mean they grow at greater rate anyway.


The only way to determine the sex of the 2019 Peregrines will be through DNA analysis.  As their feathers are now coming through the chicks are shedding down and samples of this were retained for this process.  Adult flight feathers and discarded pellets were collected from the nest platform.  Dr Deborah Dawson at the University of Sheffield Molecular Ecology Laboratory will examine the samples to determine the sex of the chicks and to try to discern any information we can about our adult birds, particularly the “new” female.


This blog will of course keep you posted of any findings as and when they are available later in the year.


As well as the usual risk assessments and safety measures taken by the ringing team  in any regular year,  this year the process was undertaken incorporating measures relating to Covid-19, social distancing and reducing the risk of any infection.  On the ascent/descent of the tower and up on the tower roof  2 metre distancing was observed by team members with the two members of the team who did have to work side-by-side being members of the same household.  The team where therefore able to observe social distancing without introducing any elements to the process which slowed things down or endangered the birds.  The birds where ringed under the necessary permits and licences required for ringing Schedule 1 protected species such as Peregrines.


Many thanks to everybody involved in the process of ringing the birds and making this possible whilst working from, not having the usual access to systems, staff and keys and whilst having to deal with the extra Covid-19 workload.  Thanks to Steve, Amy, Dean and Sorby Breck Ringing Group, to Jill and Martin who marshalled at ground level, to Glen and all the University Estates staff for facilitating and to Deborah and Phil for co-ordinating the effort.


The chicks were safely returned to the nest platform where we found them (out of the webcam shot – as per usual in 2019) and we stayed St. Georges until an adult bird returned to land.  As Alan pointed out on Twitter the adult female kept peering apprehensively up at the parapet were the ringers had appeared from.  The former intruder is wary of intruder’s herself but she has settled down this afternoon into a normal routine.


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