How Many Nests Make a Colony?

This week we visited an inspirational swift colony in Deal where an open day was being held to mark Swift Awareness Week. The first box went up on the semi-detached house in a residential street in time for the 2019 season and a pair of swifts arrived that very same year. In 2020 and 2021 three pairs of swifts nested and six young fledged both years. From then on things escalated very quickly – in 2022 there were thirteen pairs of birds producing fourteen chicks and in 2023 there were also thirteen pairs but sixteen chicks. Last year fourteen pairs of birds nested and seventeen baby swifts successfully fledged from the colony. Whilst we were standing there admiring all those boxes, the sky around the house was wonderfully alive with flights of screaming swifts.

The boxes are under the eaves on all three sides of the house – twenty seven in total. This side points north east which is actually the least popular aspect
This run of boxes, facing south east, is the most sought-after with all but one of the boxes being used. It includes the two boxes on the right which are double deckers. All the advice says not to put swift nest boxes facing south because it will be too hot for the chicks, but the boxes here are tucked in under the eaves which shade them for most of the day
Two young birds were already peeping out of the upper storey of box 21

We would like to establish our own swift colony here at home but ours is taking much, much longer to get going. Our first two boxes went up in 2019 just like the colony in Deal town, followed by another two the next year. We played loud swift calls around the boxes each summer which certainly did attract a lot of interest:

Swifts flying past the large semi-detached nest box in June 2020

But it wasn’t until 2023 that a pair of swifts started roosting in the right hand side of the large box. We installed a camera into the box that winter whilst the birds were away in Africa, so we know that they returned to breed the next summer, successfully raising two chicks. They have arrived back again this year as well, laying two eggs that have now hatched. However, things are not quite going to plan in the box but more of that later.

The large semi-detached swift box that Dave built and the two much smaller single boxes that we bought. Most of the boxes face north although the box on the right is facing east towards the sea. House martins have never shown any interest in the cups on the left, although house sparrows nest in there most years

We have recently had a new garage built with a tower that contains two swift boxes and these went into action in 2024. We are now playing swift calls from the tower rather from the boxes on the house, since the house boxes have already been discovered.

The new wildlife tower with circling swifts this summer. Once the birds have left for the year we will check the boxes to see if there is any evidence that they have been in

This week we took delivery of an exciting new piece of equipment – a thermal imaging monocular that speaks to a mobile phone.

Going forward, we hope to find many uses for this bit of kit, but we were able to put it to work immediately to see if there were birds in the wooden boxes. Here is the large swift box with the known nest shining brightly through the floor on the right-hand side:

However, I am now delighted to report that we have also been seeing a pair of swifts going in and out of the smaller box to the right:

There is a faint thermal glow coming from the box on the right where I had just seen two swifts going in

We think that these are second year birds that have now chosen a mate and identified a nest site and will hopefully be back next year as three-year olds to breed.

One morning a group of three swifts were circling the house and repeatedly peering into the box that has the nest in, before flying off and then returning shortly afterwards for another look:

These are the famous swift ‘bangers’ – young, non-breeding birds checking to see if a box is suitable, occupied or empty, sometimes knocking a wing against the box to provoke a response.

I checked the camera to see if all these shenanigans were worrying the chicks inside the box, but they were serenely sitting on their nest, seemingly untroubled by the bangers outside:

There is, however, a problem. I have realised that there is now only a single parent raising these chicks. Last year both adult birds were back in the box by dark and spent every night in there together with their two chicks. This year I have not seen both adults together since coming back from holiday on 22nd June and there is only one parent in with the chicks overnight. I presume that one of the birds has perished.

It makes me feel quite emotional to think of the remaining parent battling on alone against the odds, putting its all into bringing up its young. But although it will be hard work and may take longer, research seems to suggest that it may still be possible to have a successful outcome. The chicks certainly seem to be doing well and have started to occasionally wander off from the nest:

During last weekend’s heatwave they were clearly hot in there:

I am unsure what all this means for our budding little swift colony next year. Will the remaining parent in the semi-detached box find itself another mate for 2026? And will the pair now roosting in the smaller box to the right get safely down to Africa and back to breed? We are planning on getting a camera into the box so that we can see them if they do. There will also be three further swift boxes going up on the north-facing wall over the winter so we hope that next year will be quite exciting.

The little swift family with two chicks and a single parent cuddled up together last night. There is still quite a way to go to get them to fledging but I am cheering them on behind the scenes

One of our sons has an entomologist friend who has lent me some of her books:

I can definitely see myself using several of these books – Freshwater snails, caddisfly larvae and woodlice for sure, but some of the others might require a special effort to engage with. I don’t even know what benthic diatoms are – but I will soon because I have set myself the challenge to use every one of these books

One night this week I ran the moth trap and was slightly overwhelmed by how many moths I caught. I started going through them all including the micro moths, but quickly realised that I was going to have to just concentrate on the macro moths if I was ever to finish. As it was it took around five hours to identify and record them all. I logged 79 different species, such as three of these swallow-tailed moths, one herald and six Lozotaeniodes formosana, which is a beautiful micro moth that caught my eye:

The shining stars of the catch, though, were the three Sussex Emeralds:

These green moths have a red and white checkerboarding round the edges of their wings

The Sussex emerald is an extremely rare moth in the UK that breeds on wild carrot growing on shingle. Its main breeding site is Dungeness in Kent but it is also found in a couple of other small sites in Kent, one of which is directly below the meadows. Back in 2019 I accompanied the Butterfly Conservation ecologist down onto the shingle below the meadows on his annual count of Sussex Emerald caterpillars. He found several of them on wild carrot and I was very pleased to find one myself on some ragwort which they sometimes use as an alternative larval food plant:

This is the Sussex Emerald caterpillar that I found on ragwort in June 2019. They disguise themselves as sideshoots and are really difficult to spot

Recent conservation work at Rye Harbour to increase the growth of wild carrot has resulted in the Sussex Emerald now being confirmed as breeding there. This new site is actually in Sussex, so the moth finally once more lives up to its name.

We watched a broad-bodied chaser dabbing her abdomen down into the water of the pond in the meadows to lay her eggs:

Since she is a female broad-bodied, she should by rights be green. However the females of this species sometimes take on some of the appearance of the blue male as they age:

This female has become really quite blue – but would never be as bright a blue as a male

Craneflies aren’t noted for their beauty but these tiger craneflies, Nephrotoma flavescens, are really rather nice:

It has been hot and the ponds in the wood have been popular. It’s good to see the spotty young green woodpeckers, recently fledged from the cherry tree nest, on the trail cameras:

Sometimes they are going around with a parent:

And sometimes it is just the two siblings together:

Jays are enthusiastic bathers throughout the year:

But we only see buzzards come down in weather like this:

And tawny owls as well:

Bullfinch nest in the wood every year and they are also great pond users, so I see them a lot. Their young have now fledged – here is one out with its parents:

The bullfinch chick on the right is yet to get its black cap

And here are two bullfinch chicks on their own:

Not too long ago we dug this pond out in the open of the marjoram grove and put some green corrugated roofing material at its side to increase water run off into the pond and help keep it topped up.

Since a grass snake has been appearing on the trail camera at this pond recently, Dave looked under this green square out of curiosity and was a bit surprised to see a grass snake curled up under it. By the time I got there with my camera it had started to move off – but it was quite large:

This is the first time that I have managed to get a photo with my camera of a snake in the wood. What a treat.

Back in the meadows, a very odd-looking vessel sailed past this week. This is Canopée, a French sail-assisted freighter that launched in 2022 and was specifically designed to transport parts of the Ariane 6 rocket from European ports to the Guiana Space Centre in South America. She has a diesel engine and four wind-powered ‘Oceanwings’ which can cut the fuel consumption of the engine in half.

Dave’s photo from the meadows
Photo from the Ariane Group website

She looks amazing and is a bit of a pioneer in the quest to reduce the carbon footprint of shipping.

But I finish today with yesterday’s yoga class at Walmer Castle. What a wonderful way to start the weekend, exercising surrounded by bird song and with views down the cloud hedge borders to the Castle:

Once we are back to the short, dark days of winter, it will be difficult for me to believe that this ever happened.

8 thoughts on “How Many Nests Make a Colony?

  1. A swifty soap opera. I do hope the single parent manages ok, you will have to keep us updated. The moth trap sounds overwhelming but brilliant. I have seen a swallowtail myself recently in a friend’s garden in the evening.

  2. Thanks Judy, very enjoyable read as usual. I may not comment every time, but I do love receiving your news from Walmer Meadows. x

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