Keith Betton from the Hampshire Ornithological Society will be updating us regularly with how the Peregrines are progressing.
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12 April 2021
We are now just over a week away from the hatching of Winnie and Chester’s eggs. Several people have emailed to ask if the Peregrines feel the cold, like we do, on days like this with snow in April.
Like us, all birds are warm blooded, which means their bodies maintain a constant temperature. They are well insulated by having feathers and they take great care to keep these in good order. One adaptation shared by many animals is the ability to keep warm blood circulating near vital organs while allowing extremities to cool down. A lot of larger birds have this adaptation which is called “rete mirabile” where the arteries that transport warm blood into the legs lie in contact with the veins that return colder blood to the bird’s heart. It’s a clever system. Also you may notice that Peregrines sometimes stand on one leg on cold days and by doing this the bird reduces by half the amount of heat lost through its feet and legs.
Peregrines have large feet from a very early age, and these are really important to them as they are their killing tools. They may well tear food with their beak, but it is the feet that do most of the damage. This week’s photo shows Winnie and Chester’s chicks from 2014 with their huge feet already well developed. This was on the Police HQ that used to be on Romsey Road. We should have chicks like these in our nest in about four weeks.
Next week will be exciting for them (and us) as the chicks hatch. They should hatch in the order they were laid, with eggs 1 and 2 within a day of each other and eggs 3 and 4 later. Winnie will keep these tiny chicks warm while Chester brings in small food items. He may not always bring these to the nest as sometimes he puts them nearby for Winnie to collect.
Keep your questions coming – email@example.com
8th April 2021
So now we know Winnie and Chester are sticking with a clutch of four eggs this year. This is the normal number for Peregrines and allows them to feed each of the chicks with less chance of any going hungry.
As you can see from our photo, Winnie has been amazing at incubating her eggs and barely leaving the nest – just occasionally for a quick feed. She is usually back within 20 minutes. With the current cold weather, she will be determined to keep the eggs warm by gently pressing them close to her brood patch – an area of featherless skin on the underside of her belly which is only there in the nesting season. Feathers act as insulators so if they did not have this brood patch, they would not be able to share their warmth with the eggs. When either of them walks on the nest tray you will see that they clench their talons to avoid pricking any of the eggs by mistake.
Like all female Peregrines, Winnie does the overnight shift on the eggs because this is when they are most at risk from getting cold. With embryos developing inside any chilling of the eggs can be fatal to the unhatched chicks.
The first egg should hatch in the week beginning 19 April. The others normally hatch over 2-3 days. Often the last egg to hatch is discarded as the female can’t easily incubate it as well as the chicks. Winnie is an outstanding mum who usually hatches all her eggs regardless, so we think she will have a brood of four chicks.
Feel free to post questions about the Peregrines to firstname.lastname@example.org
22 March 2021
Winnie has now laid four eggs (the latest arrived yesterday) and we’ll now have to wait and see if she goes for five again – as in 2020. But it’s likely that she will stick with four which is the normal clutch size for a Peregrine.
She is now in full-on incubation mode which usually starts with the third egg, and for the next month she will barely leave the nest, just occasionally for a quick feed. She is usually back within 20 minutes. Chester is around of course, and this week’s photo shows him covering the eggs as Winnie returns from a break. We now think the hatch date will be somewhere around 22/23 April because of the delay in Winnie laying her second and third eggs.
People watching the cameras at night have commented that although Winnie does seem to sleep, she is also very alert, only closing her eyes for a few seconds. Peregrines at the nest mostly sleep with one eye open, and only half of their brain is alert while the other half is asleep. This is called Unihemispheric Slow-Wave Sleep (USWS) and it allows Winnie to spring into action quickly if a threat approaches, but she is still able to snooze sufficiently if no threat arises. Aren’t birds brilliant?
Feel free to post questions about the Peregrines and we’ll provide the answers here. Send your questions to email@example.com
18 March 2021
After an agonizing five days Winnie laid her second egg on Monday, and the third egg has arrived today. Having laid her first egg well ahead of schedule this delay to the second egg means she is now closer to her laying routine of 2019 and 2020. That said, we do wonder if her levels of calcium have run a bit low and maybe it is taking her body longer to create the eggshell for her eggs.
Also, as our photo shows, Winnie has now started full-time incubation which will see her keeping the eggs warm for a full month with just a few breaks. It may also mean that her clutch will be just three or four eggs rather than the five she laid last year. During this time Chester will occasionally take a turn covering the eggs and we have been pleased to see him a few times this week. If the clutch is as large as five eggs it can be hard for the male to cover the eggs as he is smaller than the female.
The average size of the eggs is 51mm x 41mm. They are usually a warm brown in colour, but often there is individual variation within the clutch, and the final egg can sometimes be a lighter shade.
15 March 2021
The last few days have been very confusing. Winnie laid her first egg on 10 March, a week ahead of schedule. Peregrines do not usually start full-time incubation of their eggs until the third or fourth egg has been laid, so we expected the second egg to arrive on 12 March and the third egg on 14 March….. but nothing happened! Winnie has been on and off the nest, guarding her one egg at night and acting completely normally – except that she has not laid any more eggs.
It is hard to be sure about what is happening here, but it may be that Winnie is waiting to get her egg-laying back onto her normal schedule, which would mean that she will start laying again this week. It is also possible that her body is currently low in calcium which she needs to make the eggshell. She has been eating quite lot of the grit in the last two days which may be a sign that she is trying to build up her reserves. Or it could be that she is just not in top condition this year and is having to take things slowly. Fingers are crossed that she manages to complete her clutch this week.
We have not seen Chester on camera since the first egg arrived, although he was very attentive that day. Some people have been worried about this, but we think it is likely that he is keeping watch nearby. Hopefully, this week will result in more eggs and the reappearance of Chester on the cameras!
12 March 2021
Friday 12 March 2021
We are expecting Winnie to lay her second egg today.
Lots of people are asking why Winnie is not incubating her first egg. Don’t worry – it’s all part of her plan. Think of it like preparing a meal and having several things that need heating up. If you start heating them all as soon as you prepare them, you’ll end up with things being ready at different times, so it is better to have a plan where everything reaches the right temperature at the same time.
So, waiting to start incubation is her way of ensuring that at least half of the eggs hatch at the same time – over maybe 2-3 days and not 6-7 days.
She can decide when to start incubating her eggs. Once she starts doing that the embryos will begin to grow so then she needs to keep sitting on them with just a few short breaks. Sometimes Chester will take over at this point, but not always. In fact, last year he seemed to enjoy doing the incubation too much and Winnie returned, and he refused to let her take over!
Probably she will properly incubate from Sunday onwards. Usually, she will start full incubation with the third egg. However,if it rains a lot, she will cover the eggs. She is a great parent – and we have known her for nine years in Winchester.
Feel free to ask questions – firstname.lastname@example.org
10 March 2021
Winnie and Chester have been getting ready for the big event – the first egg – and today it was laid at 1425 on a cold windy day. This is a week earlier than usual.
They have been seen mating a few times and that will continue even after the eggs have been laid as a way of reinforcing their bond. Owen Crawhaw managed to get a great photo of them.
Winnie is the one who spends a lot of time by the nest, but Chester is around and recently he helped to see off two other Peregrines who may have been prospecting for a nest site. While other Peregrines can pass over they are not allowed to stop! The nearest that a pair will tolerate another pair is around a mile.
We are expecting the first egg to hatch on 20 April
22 February 2021
In the last week Winnie and Chester have made brief visits to the nest every day and have been checking that the nest “dent” is still there. On several occasions Winnie has been eating the gravel in the nest tray. Both birds do this to help clear any fatty deposits in their digestive tract that may be building up from the meat that they eat. This week’s photo shows Winnie doing that.
In 2020 the first egg appeared on 16 March – so make a note to keep watching that day. Eggs are often laid just after sunrise.
15 February 2021
It’s nearly spring so the cameras are on! Winnie and Chester are around so we can expect to see them visiting the nest tray more and more in the coming weeks. At this stage they can occasionally be seen bowing to each other, but in particular look out for them making a dent in the soft shingle. Either bird (but mostly Winnie) will push their breast against the shingle and push forward to make a dent. They do this most days – and apart from making the dent it reinforces their relationship with the nest. It’s like us dusting a room when it doesn’t need it!
By mid-March we expect Winnie to be laying eggs – and last year she laid five – which is exceptional. Feel free to ask questions about what you are seeing by emailing me at email@example.com