Guessing Game

She sits, steadfast. Diligently brooding her clutch day and night, keeping her eggs warm so the chicks are able to develop inside. We hope the process goes smoothly and to nature’s plan. She has 4 eggs this year, laid between the 18th and 26th of March.

The standard incubation period for Sheffield Peregrines has been 31 or 32 days over the years. That is, in most years, the first egg has hatched either 31 or 32 days after the last egg was laid. Last year was an exception, we did not see a chick until 36 days had passed after the clutch was completed and to our surprise both eggs then hatched within a couple of hours of each other. As this is the only the 2nd year this female has bred we can only guess if it will be 36 days again? One thing which has become apparent over these recent years of well-watched urban Peregines is that no two Peregrines are exactly the same, they each appear to have their quirks.

As the final egg was laid on 26th March the key dates are therefore – Monday 26th April (31 days after last lay), Tuesday 27th April (32 days after last lay) and Saturday 1st May (36 days after). Mark them in your diary… and all the days in between! It looks like we have at least 7 days of waiting to go.

However, there may just be a but….

Unusually, as previously noted here, this year each egg has been brooded pretty much around-the-clock, ever since it was laid. Even the first egg, laid 18th March, was barely left unbrooded or unattended and never for more than a few short minutes. Could we be in for a surprise? Work those numbers again and 32 days from the 18th of March is….. (drum roll) TODAY! Perhaps this won’t be a slow week of watching a motionless falcon after all? Who knows? Predicting wildlife is a fools game but as each egg has several days of incubation ahead of the next I’d be surprsied if we see synchronised hatching as we did in 2020.

Now is not the time to look away. A fidgeting falcon and the first little white ball of fluff may not be too far off. Anyone for a sweepstake?

What next?

As I write this blog on Sunday evening we currently have 4 eggs. Will we get another? It’s not impossible but a Peregrine Falcon laying 3 or 4 eggs is much more common than 5 in the UK.

The eggs this year so far have been laid on a (very roughly) 60 hour cycle so that would mean a 5th egg would be due on Sunday evening 6pm (as I type!). Although the gap between eggs 3 and 4 was more like 62 hours.

Ordinarily, one of the key indicators that laying has finished, that the clutch is complete, is an obvious switch by the adults from brooding the eggs part-time to full-time. Generally it is normal for the first laid eggs to go unbrooded/uncovered for periods of time during the day, often 20-30 minutes at at time. Then, by instinct, the female will know when she’s laid her last egg and she will then keep the eggs warm full time. The male usually quickly cottons on to this too.

This behaviour switch will not be so apparent this year because, interestingly, our Falcon has been very diligently been brooding ever since laying her first egg on 18th March. There have been very few times when the eggs have been exposed to the elements for more than a minute or two. These eggs are being well looked after so far.

Last year both chicks hatched within a couple of hours of each other indicating very equal brooding times and the chicks developing inside the eggs at the same rate. Hatching this year may well be much more asynchronous given that egg 1 has been well brooded for 10 days already. Only time will tell.

If you are reading this on the evening of Monday 29th March (or after) and there’s no news of a 5th egg on this blog or on @SheffPeregrines Twitter account then its safe to say the clutch is complete.

One behaviour change you may have noticed already is hunting and prey provision. The Falcon has been doing the vast majority of the incubating and the Tiercel has therefore been placed in charge of providing her with food. As we know the Falcon is a prolific hunter and the vast majority of food items we see her bring back to the ledge are pigeons. In fact, compared to other sites around the country the Sheffield Peregrine diet is really quite boring, pigeon after pigeon with the odd Magpie or Gull every now and again. Not a surprise such a big, strong female prefers to take nice big dinners. The last 10 days though has seen a more varied diet now that the male is the sole hunter, with a couple of Blackbirds brought in and at least one Chaffinch. Keep your eyes peeled to see if this trend of a wider variety of smaller preys species continues if you can. Ed Drewitt down in Bristol is continuing to monitor the prey items taken into numerous Peregrine nests across across England – any prey items you see and can identify, or can get a screen grab of, or even just note the time of, please tweet @SheffPeregrines so details can be passed on to Ed. The Wakefield Peregrines were observed bringing in a Crossbill to their nest a couple of days ago, the first time this species has been recorded on a UK PeregrineCam. We are learning all the time.

One other change from the 29th, affecting people not Peregrines, is the “stay at home” advice ends and changes to “stay local.” This blog makes no comment on how clear these rules are or how they should be interpreted. The changes may mean some people now feel able to visit St. George’s to view the birds. If doing so please respect other people in the area, maintain 2 metre distance at all times and observe the rule of six to maintain the good reputation of Peregrine enthusiasts. The land at St Georges is unversity property so please observe any instructions given by uni staff if they happen to be on site.

Egg Four

Just a quick note to confirm that a fourth egg was laid on Friday morning as had been hoped and anticipated. It took a while to be able to confirm it though!

Eagle-eyed observer Sue saw what she thought was egg laying activity just before 6am and tweeted to let everybody know. Later Alan was able to review and tweet video of the action – it is worth a look/ if you get a chance! Clearly laying a large, hard-shelled object is not the most comfortable experience and after what looked like the laying event the Falcon toppled over, almost doing a forward role! She certainly seemed startled! The bird recovered quickly and was back down onto the clutch immediately.

Throughout all this action no eggs could be seen so the evidence of a new egg was only circumstantial. When the first leg-stretch/changeover of the day came at 6.30am the clutch was partially obscured behind the side of the platform and to all intents and purposes looked like there were only 3 eggs.

Despite lots of eyes watching the birds all day a visual sighting of 4 eggs together proved impossible – the eggs spent most of the day under incubating parents, mainly the female. When we did get a glimpse only 3 could be seen. I was beginning to doubt there was a 4th egg! Maybe we had jumped to the wrong conclusion?

Eventually, on Saturday afternoon, over 24 hours after the “lay,” Alan managed to tweet a screen grab showing 4 brown shapes rather than 3 – confirmation we weren’t imagining things!

That we did eventually get 4 eggs in sight is a good sign that the eggs are being moved around a little by the birds as they brood them which hopefully means they are all kept equally warm and will therefore all develop at the same rate.

It would seem safe to assume the reason why the Falcon chooses to lay her eggs tucked up at the right hand side of the platform and partially out of sight – here she gets most protection fron the prevailing westerly winds and has the best chance of keeping the clutch warm …and boy were those winds cold on Saturday morning with a dusting of snow in the nearby western suburbs of Sheffield.

Bright but chilly Saturday morning captured by @jilliano

Unfortunately that does mean we have a bit of a blind spot when it comes to seeing egg laying and hatching. Long term that issue is one which could be addressed when the time comes to upgrade/replace the cameras – which will inevitably have to happen at some point in the future as the cameras age. One of the purposes of the Sheffield Peregrines Virgin MoneyGiving fundraiser would be to contribute towards improved cameras as well as funding further DNA study. Please do consider making a donation, however small, if you can. Follow the link at the top right of this page.

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and then there were three…

A third egg has been laid this afternoon. So far this month we’ve had the earliest egg ever and the clutch is now bigger than last year’s. Will we get a 4th egg? Maybe, maybe not. We’ll know by Thursday evening or Friday morning. The Falcon is on roughly a 58-60 hour cycle between eggs. My money is on 2am Friday morning. Anybody fancy staying up to watch?

Egg 2

The second egg was laid some time overnight on Saturday night/Sunday morning and was revealed on camera at breakfast time. Two eggs equals last years complete clutch, will we get more this year? I would expect so. A clutch of 3, 4 and sometimes 5 eggs is typical.

The Eggs do not get incubated full time until the clutch is complete so don’t be alarmed if there’s no bird sat on the eggs sometimes. The adults have been very diligent so far and usually there’s an adult sat keeping them warm.

If there’s to be another egg Tuesday 23rd should be the day it arrives.

Egg

The first egg of 2021 was laid around dinner time this evening, Thursday 18th March. Somewhat earlier than expected, given last years first lay date was 29th March.

This is fantastic news. This is the earliest ever recorded egg at St. George’s. Peregrines have bred on the tower since 2012 and we have records of first lay dates from 2013. The previous early record was 19th March in 2015 & 2016. So we’ve beaten that by one day. Eggs are beggining to be laid at Peregrine sites across the UK now in the last week. It’s nice to be amongst the early starters.

Peregrines typically will lay an egg approximately every 48 hours until the clutch is complete. If all is going to plan we should expect another egg perhaps on Saturday evening, it could be a little sooner or a bit later. Last year there was a gap of almost 72 hours between egg 1 and egg 2, which were the only eggs laid.

The first glimpse of the egg shortly before darkness fell.

The Falcon sleeps as she broods her egg tonight and keeps it warm.

Generations

Although we have watched and witnessed so much over the lifetime of the Sheffield Peregrine project, we know very little so far about what happens to the young birds born here when they leave St. Georges and enter the big, wide, avian world. We have no means of calculating survival rates or success. A total of 22 chicks have fledged from St.Georges. Through the returns of rings we know of a couple of birds who have definitely perished. Through the sighting and reading of rings on live birds we know of a couple of birds who have moved on and successfully spread out beyond Sheffield but, the truth be told, the whereabouts and fate of most of our young falcons is a complete mystery. We have no idea just how many successfully adapt to the rigours of hunting and feeding and surviving out in the landscape, town or country, through a fist British winter and beyond.

The 2017 chicks, just before their first flights

We thankfully know that one of the 2020 chicks has survived the winter because they are still in residence around St. Georges and being tolerated by the parent birds. So far….

Theoretically there could be several Sheffield birds out there, male or female, successfully raising chicks of their own. They could be re-occupying a traditional rural Peregrine territory in the Peaks, or pioneering new urban territories in town and cities of the north or midlands. Maybe they got fed up of City life and headed to the coast for a life on the cliffs and soaring on the sea breeze? Or maybe they succumbed to the cold or to hunger? Many birds of prey species have a high natural mortality rate in juveniles and this applies to young Peregrines in particular with mortality rates shown to be 60 – 70% in the first year. Honing the skills of aerial attack and catching enough food to sustain as a top predator, ambushing prey by surprise, at breath-taking speed is no easy task. Only the strongest survive. And then there are the added perils of human persecution, Peregrines still have enemies armed with shotguns, traps or poison.

a 2016 chick was found dead west of Bradford in 2018 and traced by its silver BTO leg ring (graphic c/o E Hughes)

But there is one Sheffield bird who we are lucky enough to know the fate of: In 2018 we learnt that a 2014 Sheffield fledgling is the male bird in the very successful Peregrine territory at Wakefield Catherdal. As this Peregrine site has a live webcam feed, a Twitter account and an excellent blog we know quite a bit about this well watched bird. He was identified from his leg ring GC20732 which was eventually read from photographs after many attempts by the Wakefield project! (Silver rings are hard to see let alone get a clear shot of to read).

GC20732 was one of 4 chicks to fledge from St. Georges in 2014

From checking images there is confidence that GC20732 has been the resident Wakefield male right back to the very first year their webcams were installed in 2015 when GC20732 bred in his first summer, still not yet fully into his adult plumage. Since then, 21 of his chicks have fledged from Wakefield cathedral. 21 birds into the next generation of UK Peregrines. 21 Sheffield grandchildren if you want to think of it that way. As with the Sheffield offspring little is known about the fate of these young West Yorkshire Peregrines once they disperse but that has finally changed this year…

The 2019 cohort of Wakefield chicks were all given bright orange darvic leg rings, just as our birds were, and one of these leg rings T4F has been read on a young Peregrine who was sighted in just outside the city of Durham in January. This is fascinating news. It’s a dispersal of 72 miles from Wakefield and is 93 miles north from Sheffield, as the Peregrine flies. The young male has since been spotted several times a few miles down the road from this first sighting, near Bishop Auckland. He seems to be frequenting semi-urban areas or man-made structures adjacent to countryside rather than the local town and city centres.

Video c/o David Spiers

The above is a clip from a video which can be watched Here

It’s a tantalising glimpse into the world of young Peregrines, especially our urban Yorkshire-born Peregrines. This bird has survived 2 winters. He looks fit and well and very smart. He has been able to navigate to a place of his own where he may have settled down. Maybe he bred last year? Or maybe it’s just a short stop off on a young raptor’s wanderings as he looks for a territory and a mate?

If he continues in this vein and birders manage to read his leg ring wherever he may wander, then there’s a chance of the first evidence of another new generation of birds with links back to St. Georges. Hopefully the use of coloured wings will mean we’ll learn a little bit more in the coming years of where our Peregrines go. We’ll come back to the subject of dispersal in a future blog post…

T4F on a viaduct in Co Durham. Photo Copyright George Thompson

Many thanks to Francis at Wakefield Peregrines, David Spiers and George Thompson for assisting with this post.

The excellent Wakefield Peregrine webcams and blog can be found here: https://wakefieldperegrines.com

Right on cue….

After musing about bonding activity in last weeks blog, the birds have been seen on camera this week doing just that, bowing and clucking to one another – right on cue. It’s aways helpful when they do this in the nest platform on the close-up camera rather than disappearing round the corner of the tower.

A good video of it can be seen here courtesy of @doggie3132 ‘s Twitter feed https://twitter.com/doggie3132/status/1366463035385249792 watch from 2.47 to see the two birds together. It’s a good shot to see the contrast between the darker female and the lighter backed male.

I haven’t been able to watch very often this week so I haven’t seen the juvenile all week but that doesn’t mean he/she isn’t around. Please do tweet your sightings of any interesting activity to @SheffPeregrines or @shefbirdstudy. Has anybody seen the male offering the female food? It’s a key part of the bonding process at this time of year, the male reminding the female that he’s up to the job.

Harking Back, Looking Forward

As March begins we enter Peregrine season proper. This is the month when we expect to see some action! Across the UK urban Peregrine nests with webcams and Twitter feeds are reporting more frequent visits from their birds, male and female birds being seen together more frequently, brief glimpses of courtship behaviour and even a copulation attempt or two.

Here in Sheffield we continue to see the birds frequently on the nest platform as we have been doing since December. There are 3 birds appearing on camera; the female, the male and one of last year’s youngsters. Personally I am not seeing that much of the male bird but I’m not able to watch all of the time so that’s not a particularly scientific observation, it may just be a matter of timing on my part. The female is present for large amounts of time now and is the bird I see most often on camera. She will not stray too far now and is firmly in place to defend her territory, ready for breeding. She is often accompanied by the juvenile bird, just hanging around or begging for food if a kill has been made. I haven’t seen the adult male at the platform at the same time as the juvenile for a while now but, again, that could just be me.

The lingering 2020 juvenile

It will be interesting to see what happens this month as the days get longer and Peregrine hormones switch the birds on to breeding.

Will the young bird hang around?

Will it still be fed?

Will it be forced out?

Time will tell.

We haven’t had a juvenile bird linger like this at St. Georges previously, typically the fledged juveniles have quietly moved on come September/October time. In most cases to destinations unknown….

Expect to see the male and female bonding in and around the nest platform, they will face each other and bow their heads down and make loud contact noises to each other which, frankly, I can only describe as clucking! They will make a right old racket – this is not the sweet sound of songbird! Individually look out for either one of the birds scraping about in the nest platform substrate – the result being the creation of a little depression for eggs to be laid in. Don’t expect both birds to do this in the same place! If you do see any sort of bonding or breeding behaviour please do take a screen grab or short video and tweet it to @SheffPeregrines – we aren’t all necessarily able to watch the feed all of the time.

Bowing behaviour March 2015

As this pair have only bred together once before it is a little difficult to predict what schedule they will be on. As mentioned above some Peregrine pairs elsewhere are showing clear signs of courtship & copulation. We’re definitely not that far along yet. All we have to go on are last years timings – a summary of which are made below. In 2020 this pair kicked off with laying their first egg on March 29th. This is somewhat later than we were used to in Sheffield with the previous female (or females). Over the 4 years from 2014 – 2017, Sheffield first laying dates were consistently the 19th or 20th of March. In those years very obvious pair bonding and copulation could be seen as March began. Things would have to speed up very quickly if we were to hit similar dates this year. Only the birds will know when they are ready. Let’s hope that things progress nicely and we see some mating and egg laying before March is out. The days will be much longer by then too. All things to look forward to.

2020 Summary:

1st Egg laid: 29th March

2nd Egg laid: 31stMarch/1st April

Chicks hatched: 7th May

Chicks ringed: 27th May TRF & TNF

Chicks fledged: TRF 15th June, TNF ?16th June?

Fast Food

At the start of the month an appointment in the City Centre allowed me to drop in on the Peregrines for the first time in a long time.  It was late afternoon, nearing dusk.  Two birds were present on the tower but the smaller one took to the skies whilst I was still too far away to identify them properly.  The male I assumed.

I arrived in the church grounds at about 16.27.  The remaining bird on the perch was the female, the falcon.

The falcon, casting her eye down on me

A quick scout around the base of the tower and the church yard for prey remains revealed a plethora of pigeon feathers.  Not unexpected,  the amount of feathers are a further indication of the continued and regular occupation of St. Georges tower we have seen throughout the winter …..and of the Sheffield Peregrines predilection for Pigeon.  

I glanced up and the female departed the tower in the dropping light.  Time 16.30.

A further wander round the church yard revealed prey remains of a Magpie which had been blown or discarded from the platform.  A new one on me, I’ve not noticed Sheffield Peregrines with a Magpie before.  Which is perhaps surprising given their regular presence in the area.  Not exactly the strongest fliers either.  

Magpie remains

I scanned the skies and a Peregrine appeared.  I raised my binoculars to see it carrying a pure white feral pigeon, seemingly still alive.  It pushed back it’s wings and arrowed in towards the platform.  It landed.  I checked my phone, 16.34.  It was the falcon.

Quite remarkable.  Take-off, traverse to hunting area, gain altitude for attack, select target, make attack, ferry bulky prey back to the platform.  All in the space of 4 minutes!  Had the trees of the churchyard not obscured my view I may well have been able to watch the entire hunt play out in front of me.

On another day I could have spent 15 minutes at St. Georges and drawn a complete blank.  Today I not only saw two birds, I also had the privilege to witness first hand just how efficient a hunter this female is.  No wonder that this bird usurped the previous resident female.  This is clearly a fit and powerful bird in it’s prime.  Fascinating and a little surprising to encounter such behaviour.  Perhaps she had even identified her target even before she took to the wing?  

She rested on the stone ledge adjacent to the nest platform, breathing heavily.  A few minutes later a second smaller bird came in and landed on the stonework below her.  A smaller bird, with very soft and fresh looking silvery feathers, it started to beg and continued to do so for 15 minutes.  A tantalising glimpse of orange ring on its leg confirms that this is one of last years youngsters.

The silvery breast and fresh feathers of the juvenile. Note how the yellow eye ring has not yet developed.

This is great news.  A 2020 Sheffield fledgling is confirmed as alive and well.  In most other years, our youngsters have long departed the natal territory, their whereabouts and wellbeing unknown more often than not.  But at least one of 2020’s cohort has survived the winter although it is clearly not yet fully independent.  What a pity lockdown has prevented us from spending time at St Georges to observe this juvenile’s interaction with its parents.  It would be great to be able to spend some time and get the chance to see and photograph the orange leg ring and see which bird it is.

Junior moved up to the perch and continued to beg loudly as dinner is prepared.

Fast forward two weeks to mid-February and the hunting record is smashed again.  On Weds 17th Feb @doggie3132 records the female leave the nest and return with prey only 2 minutes and 20 seconds later.  The pigeon is still alive so has not come from any larder.  Nice spot by @doggie3132.  His video is here https://twitter.com/doggie3132/status/1362094949660057606?s=20.  

Fast Food indeed.

The light faded quickly as the pigeon was plucked.