Peregrine falcons at Worcester Cathedral

[G-CPTN]

Someone asked what happened to the 'fluff' feathers - the latest pictures show the flight feathers 'grow through' the fluff.

I wonder what prevents the chicks from 'taking off' before the flight feathers are ready?

[Opsboi]

Someone asked what happened to the 'fluff' feathers - the latest pictures show the flight feathers 'grow through' the fluff.

I wonder what prevents the chicks from 'taking off' before the flight feathers are ready?

They've been going a lot wingcercise in the last few days - they'll know instinctively when they feel a hint of lift, I'm guessing

[Hydromet]

Someone asked what happened to the 'fluff' feathers - the latest pictures show the flight feathers 'grow through' the fluff.

I wonder what prevents the chicks from 'taking off' before the flight feathers are ready?

Instinctive fear of heights?

Good morning all, currently clear blue sky, 8C, forecast max 20C. About to drop car off for a service then a nice early walk home.

[Opsboi]

One of them is out on the projecting perch looking very interested...

[Rossian]

Questions questions. Most predators have eyes at the front of their faces to enable stereoscopic vision for distance judgement (vide owls). How do our birds judge distance when they go for the "stoop" to kill the prey given that they are going for a moving target and the relative speeds involved? Bloody clever I think. Any ideas, anyone?

The Ancient Mariner

[izod tester]

The Facebook page has a short video of one of the youngsters slipping off one of the perches this morning. Apparently, a semi controlled flutter down to ground level and currently being checked over by the local birdwatch crew.

[G-CPTN]

Ooer missus.

[Rossian]

Looking just now (1330), I think that the big one on the platform is carrying too much fluff which would cause "parasitic drag??" and generate a plunge to earth. The one on the perch looks much sleeker and possibly aerodynamic.
What am I going to watch when they've all gone? I've enjoyed the past few weeks.

The Ancient Mariner

[Fox3WheresMyBanana]

For hitting a moving target, when the predator is also moving, there are two basic options; pure pursuit and lead.
Pure pursuit involves keeping the target in the same place in the predator's visual field. That may be directly in front, or some offset.
When the prey's movement displaces it from the selected point in the visual field, the predator changes its direction of movement to put it back in the selected place.
If the prey keeps moving relative to the predator, then the situation usually ends up in a tailchase, with the predator behind the prey.
As the chase continues, any further change in direction results in the predator being able to cut the corner and further gain on the prey. This continues until intercept.
This method is very simple for the predator, and works when the predator has a significant speed advantage and sufficient energy for longer than a short chase.
Lead involves the predator anticipating the movement of the prey, and continually changing direction to keep the prey in the same point in the visual field.
A predator normally learns the necessary lead for a particular prey from experience. Pulling lead on the target needs less speed advantage for the predator, and uses less energy overall.
If the target keeps turning, the predator can achieve an intercept even if it is a bit slower than the prey.
I expect most predators start with pure pursuit when young, and attempt to achieve the correct lead with experience, since this uses less energy overall, and so allows survival on fewer prey.

Falcons generally avoid having to chase their prey. They come down from near vertical, since it is both difficult and energy consuming for the prey to keep checking straight up.
The falcon's altitude on the perch is chosen so that its horizontal movement does not produce sufficient angular motion for the prey to be alerted.
The position is normally chosen so that the falcon's shadow does not alert the prey either.
The falcon's only problem is thus timing the intercept so it can just grab the prey at the bottom of the dive. Too high and the prey is missed, too low and the ground is hit.

Of course the prey have evolved to counteract these techniques, but it would be a very long post to list all the usual methods.

All this applies to flying air defence, of course.
Where a target had excellent lookout and the ability to turn in tighter circles than a fighter, e.g. slow, multi-crew(lots of eyes!) aircraft like tactical transports and helicopters, I used to use the falcon's method.

[Opsboi]

The Facebook page has a short video of one of the youngsters slipping off one of the perches this morning. Apparently, a semi controlled flutter down to ground level and currently being checked over by the local birdwatch crew.

They've put him back up there now

Good on them

[Rossian]

......Ah but, ah but ah but Fox I understand about curve of pursuit and lead but you were using you front-facing-steely-fighter-pilot eyes for distance judgement, the falcon's eyes are on each side of the head so how do they judge distance? That was the essence of my question at #65. They are still v. impressive I think.

The Ancient Mariner

[Fox3WheresMyBanana]

More on the vision of peregrine falcons here
https://intobirds.com/eyes-of-a-peregrine-falcon/

[Rossian]

.....thanks for posting that, I thought that was a good explanation.

The Ancient Mariner

[Hydromet]

We occasionally have brown goshawks here. The one successful strike that I've seen was on a spotted dove that was sitting on our verandah, completely unaware of the goshawk's presence, and probably never knew what hit it. On several other occasions I've been alerted to the goshawks' presence by seeing crested pigeons hiding - once in an overturned empty flower pot and once in our doorway recess. I've also seen an unsuccessful hit on a noisy miner, which was one of a flock that was aware of the goshawk's presence. I heard the miners, saw a puff of feathers, then the flock started harassing the goshawk until it left.
I vaguely remember reading somewhere that raptors need to average about one kill per seven strikes to have a positive energy balance.

[Hydromet]

Just had a look. Looks like one adult on the board, one adult & one youngster on one perch, the other youngster on the other perch. Looks very much like they're tryig to muster up courage to go.

[Hydromet]

I can only see one there now. Hope the others are OK.

[Karearea]

I can only see one there now. Hope the others are OK.

Rogues Gallery! Do not be fooled by their cute demeanours
Firstly we have XRH. Over balanced and slipped off the turret perch at about 9pm last night whilst exercising. Only went as far as the first ledge, same area where XNH spent 26 hours earlier in the week, but still warranted a 5am check to ensure they hadn't grounded overnight. In fact they had already made their way to the gully ledge by this time which is an ideal location for new fledglings. They were seen shortly afterwards to make a strong fly off the ledge over Cathedral buildings, before returning again and posing for photos.
Second we have XNH. After their afore mentioned night on the tiles, XNH liked the look of the Green when they and XSH came off the perch at around 07.30 today. We aren't sure who took who out this time, but XNH covered a good bit of air to end up where they were found. They were quite compliant (or resigned) when boxed and released in the gully with just a few scowls. Within a couple of hours they too had hopped onto the gully wall and joined XRH.
Finally it's XSH who we eventually found on a tiled roof just off Cathedral grounds, after being alerted by a group of vocal crows who weren't too welcoming to their visitor. In fact SH had an eventful few hours out with the predictable gull harassment and, to our amusement, a very aggravated male Blackbird. Our main concern was that XSH was a little too close to a busy road for when they made their next unpredictable flight, or could slip down into a public area. After a few hours, with their confidence noticeably increasing and encouragement from an overhead Mrs P, XSH hopped across the terraced roof line before flying across to join their two siblings.
A good result to end what has been a long day for the monitoring team.

- from the FB page post of 5 hours ago

[G-CPTN]

Thanks for the update.

[Hydromet]

Thank you. glad they're all good.

[Karearea]

Link to the Facebook page: https://www.facebook.com/worcesterperegrines

Is accessible without being a FB member, just X the 'see more/log-in' box away.

Some good photos there and more information and updates.