The 2011 Nestbox Diary

May (part 2)

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16 May - The situation in SW-le hasn't changed over the last few nights,

Activity in Swift boxes, 15/16 May


with just one bird in residence, although a second bird clearly appears during the day, as shown in the final picture in this sequence.

I can see no evidence of any activity in SW-lo and SW-ri.



Swifts in residence tonight, 16 May



An update tonight - both birds are present in SW-le tonight!





17 May - And this morning everything seems to be all well in the two occupied boxes.

Swift and Sparrow activity this morning, 17 May


While the pair in SW-up were in residence when I 'looked', SW-le was empty. However, the good news is that the pair in that box have been bringing in feathers over the last few days - excellent.

The image also confirms that at least one Sparrow continues to take an interest in the boxes!


Early evening webcam image, 17 May


A check of the webcam again in the early evening showed SW-up occupied by the pair again, and although SW-le was still empty, movement of the feathers indicated that there had been visits during the day.

Also, there were signs that both SW-lo and SW-ri had been visited - Sparrows?



Swifts in residence tonight, 17 May



Tonight once again we have both pairs of Swifts in residence, which is good to see after the uncertainty of a few days ago.





18 May - During the day I checked the webcam several times and found at least one in residence in SW-up each time, leaving me wondering if there are already eggs in that nest. Both pairs of Swifts were in their boxes last night.




19 May - It's the same situation today, with SW-up occupied each time I look, and all four birds present tonight. While there may have been a sparrow visit to SW-lo yesterday, I can't see any signs of activity in the two unoccupied boxes today.



21 May - The first egg is laid in SW-le

Swifts - first egg laid in SW-le, 21 MayWhile I am still waiting to confirm the presence of egg(s) in SW-up, a check of the webcam at lunchtime revealed that an egg has been laid in SW-le today.

The presence of a bird in SW-up every time I have checked the webcam since the 16th does indicate that eggs are being incubated in that box. We will be heading home tomorrow, and then I'll be able to go through my recordings to confirm this.





22 May - Back home this afternoon, and now able to start filling in some of the gaps left by trying to follow progress from the wilds of the Lizard Peninsular!

Relying on my mobile phone to monitor the boxes from Cornwall is interesting.  Phone Reception is hit and miss to say the least - just getting a signal in or around the bungalow is a challenge, and what appears to be a good spot turns out to be useless just a minute later!

Anyway, a brief look back through the recordings have confirmed the presence of eggs in SW-up, although they weren't laid as soon as I thought. There are now three eggs in that box.

The first was laid during the morning of the 16th, and was visible for the first time at 8.23am.

The second egg was not laid until the 18th - not seen until 3.33pm

It wasn't until the 21st that the third egg was added to the clutch, and it wasn't until 9.06pm that it became visible when the eggs were uncovered for the first time all day.

As I prepared to write this, one of the pair in SW-up returned to the box with a large feather and took over sitting from its partner which left a minute or so later.

Last year this pair laid just two eggs, on the 20th and 22 May, so they are four days earlier this time.

As reported above, the first egg in SW-le was also laid on the 21st, and in that case it was first uncovered at 12.01pm.

last year this pair laid their first egg on 24 May, with a second one on 26 May.  So they appear to be three days earlier this time.





23 May - The morning was sunny but getting very blustery, with Farnborough airfield recording south-westerly wind speeds of over 30mph by noon.

While there is constantly a bird in residence in SW-up,  the pair in SW-le have been coming and going during the morning,


Swift egg in SW-le ( laid 2 days ago), 23 May



and the single egg that was laid two days ago




Swift pair with egg in SW-le, 23 May



is still alone as we go into the afternoon.





Swift pair in SW-le (showing 'white-spot', the female), 23 May


When this pair first occupied SW-le in 2009 I was able to identify one that I subsequently named as 'White Spot', and here it is with those small white patches on the back of the head. This is the female.



The two pairs of Swifts in residence tonight, 23 May



Tonight there is still just one egg in SW-le, but after a very windy day, with drizzly conditions this evening I was glad to see all four birds safely 'home'.





24 May - Egg #2 in SW-le

A bright, sunny morning with little sign of the wind that troubled us yesterday.

Female Swift ('white-spot') in SW-le this morning, 24 May


In SW-up incubation continues and in SW-ri the pair now have their second egg.

A  first look through the recording doesn't reveal exactly when the egg was laid. However, White-spot remained in place, keeping the nest cup hidden, before her partner left at 9.50am  and then remained there,



A second egg is revealed in SW-le, 24 May


until she decided to leave for a few minutes at just before 11am, revealing the new addition to the camera for the first time.

The eggs were left unattended for quite a lot of the day, suggesting that there may be another egg to come before incubation begins.  The only visits during the day were made by 'White-spot' herself.





3 eggs revealed as Swifts change over in SW-up, 24 MayIn SW-up the contrast couldn't be greater. In the twelve hours from 9.30am to 9.30pm that box was occupied at all times by one or other of the pair, with just six change-overs being recorded.

This picture shows the last swop to take place (at 9.20pm), and the only time during the day when all three eggs were visible for just a few seconds. The second bird returned for the night at 9.31pm.


Swift with parasitic flat-fly (Crataerina pallida), 24 May



The Swifts have their usual  passengers in the form of the parasitic flat-fly Crataerina paillida. During the winter I removed any pupal cases I could find in the old nest in this box, but either I missed a few or the Swifts brought in adults on their return.





25 May - A bright, sunny day with a steady south-westerly breeze of around 14-15mph breeze and the temperature up to 19C by 1pm.

The improved conditions have brought the Swifts back into the sky over us and I've even heard a few screams! At the moment numbers are low and I could account for just six birds during the course of the morning. I'm still trying to confirm whether or not there is a pair actually nesting in my neighbours' loft. I must ask if they have heard any noises from up there.

It was interesting to compare our two pairs this morning. It was an earlier start in SW-up, with one bird leaving the box at 6.05am, returning ten minutes later. It was 7.28am before the other bird left to start the day's sequence of change-overs. Between then and 1.30pm the individual sitting on the eggs swopped places just three times. The change-overs lasted around 3-4 minutes. This mornings timings correspond roughly to what I saw yesterday with each 'shift' on the eggs lasting an average of around two hours.

The pair in SW-le had a slower start, with the male leaving for the first time at 8.02am. He had not returned when the female left at 9.38am but did appear at 9.55am to sit on the eggs. The female returned at 10.25am but the male stayed for fifteen minutes before leaving.

Between then and 2.30pm there were three more change-overs, lasting between 2 - 5 minutes.

Swift pair with eggs (in SW-le), 25 May


This picture of the change-over just after 1.30pm was the only time that the nest cup was left uncovered since first thing this morning, confirming that no new addition was made to the clutch since then.

With a pattern of incubation now being established it may be that this pair will have just these two eggs, as was the case (for both pairs) in 2010. If this is the case, why didn't incubation get started yesterday - were they 'hoping' for a third one?


I spoke too soon when I wrote that last paragraph. We were out of a few hours during the afternoon and in that time any semblance of an incubating pattern in SW-le fell apart.

Between 2pm and 3.30pm it was the male that sat on the eggs. However, when he left the eggs were left unattended until both birds returned within two minutes of each other at just before 6.45pm. The male left again at 7.19pm with his partner heading out at 8.50pm. They returned for the night at 9.19pm (male) and 9.25pm (female).

In the meantime the pair in Sw-up continued with their routine with three more change-overs (during which the eggs remained hidden) before they settled down for the night.





26 May - A grey, blustery day with occasional rain showers (a couple quite heavy) during the afternoon.

The puzzling behaviour of the pair in SW-le has become somewhat more so today. While the first bird didn't leave SW-up until 8.45am, the male from SW-le left at 4.45am, followed by his partner at 5.02am. They both returned two minutes later, but the female left again a minute later and stayed out for twenty minutes.

When the male left again at 8.34am he stayed away for the rest of the morning and afternoon. The female remained on the eggs for over six hours before leaving the box at 11.49am. During the afternoon (up to 6.14pm) she returned to the nest five times, but spent far less than half the afternoon sitting.

The timings were:

11.49 out - 12.07 in
12.40 out - 12.43 in
13.30 out - 14.05 in
14.35 out - 14.38 in
15.29 out - 18.14 in


Swift nest with feathers  in SW-le this afternoon, 26 MayEach time that the female returned during the morning and afternoon she brought in a feather, and the apparently random timings of the returns may well have resulted from when she happened to collect them.

This was the nest during her longest absence. By next year I may replace the cameras in these two boxes with higher resolution versions in order to improve the sharpness of images like this.


As the evening progressed, the female left again at 7.26pm, leaving the eggs unattended for another twenty minutes before returning at 7.46pm. Five minutes later her partner arrived for the first time since 8.34am. The two birds remained together until the female went out once more at 8.21pm. The male remained on the eggs for the next forty minutes before he too departed.


The Swift pair together again tonight, 26 May


Finally, the pair returned for the night at 9.18pm (F) and 9.20pm (M). A quick calculation shows that during the day they left the egg unattended for just under 4¼ hours (compared with the eggs in SW-up being visible for no more than a second during a change-over!).

This certainly isn't the behaviour that I would expect if the eggs are being incubated. Is it possible that she is still waiting for a third egg?



Feathers were also being collected by the birds from SW-up, although in their case there was always at least one of the pair present all day. As I mentioned above, One bird left the box at 8.45am. It returned at 9.13am with a feather before both birds settled down together for the next hour. One of them left again at 10.18am and after that the change-over routine started, with the sitting bird being relieved six times between then and 6.05pm. A feather was brought in during all but one of these exchanges.

During the course of the evening there were two more change-overs in SW-up before the pair were finally came together again for the night at 9.15pm.





27 May - A grey but dry start to the day but some sunny spells in the afternoon, and a maximum temperature of 15C.

In SW-le the part-time incubating continues. First out this morning was the female at 5.08am, returning three minutes later. Her partner didn't go out until 8.29am and he stayed out for just over an hour. six minutes later the female left - I guess that would count as the first change-over of the day. However, with no sign of the female returning after a couple of hours the male also left at 11.59am, leaving the eggs unattended for the first time today.

That state continued right through the afternoon until the female entered the box at 4.23pm. She then sat on the eggs until the male returned at 7.09pm, followed by her leaving two minutes later.

The third change-over of the day occurred at 8.51pm - the female arriving and her partner leaving two minutes later. Then at 9.25pm the female left the eggs unattended once more, although this time it was only four minutes before she returned, followed by the male five minutes later. This brought an end to the day's aerial activities, during which the eggs had been left unattended for 4hr 28min, rather longer than yesterday.

In SW-up things weren't as straight-forward as on the previous few days. Again they had a late start with the first bird leaving at 8.47am, to return four minutes later, and its partner going out at 9.13am and not returning until 9.40am.

The first bird then left again at 10.24am, this time staying away for the rest of the morning, and not returning to the box until 1.42pm. Its partner left two minutes later, and this bird remained away for nearly five hours, until 6.40pm. The subsequent change-over took nine minutes and the bird that left stayed away for the next two hours.

On its return the change-over took just two minutes with the relieved bird leaving at 8.50pm.


The eggs unattended in SW-up this evening, 27 May


Then the unexpected - at 9.11pm the sitting bird also left, leaving their eggs unattended for the first time this week.

This situation lasted some fourteen minutes before the first of the pair returned for the night at 9.25pm, followed by the second bird at 9.31pm.





28 May - The mainly grey weather continues with a south-westerly breeze a high of 15C. Our first glimpses of sunshine came in the early evening.

The occupants of the two boxes continue to demonstrate their radically different approaches to their clutches of eggs.

In SW-le the male was first out at 4.56am, returning three minutes later. At 5.04am it was the turn of the female to leave for a similar length of time. It was 9.41am when the male next headed out, not to be seen again until after 4pm. The female sat on the eggs all morning, finally leaving at 1.32pm after being in the box nearly 8½ hours.

She returned to the nest at 4.11pm after the eggs had been left unattended for 2hr 39m, and was joined by her partner at 5.31pm. He stayed with her for 22 minutes before leaving her once again.

The evening saw the female remain on the eggs for a couple of hours before once again leaving them unattended, from 8.05pm to 8.34pm, and when she returned it was only to stay for thirteen minutes before leaving again.

Finally, she re-entered the box at 9.24pm, followed closely by her partner, bringing to an end a day on which their eggs were left unattended for a total of 3¾ hours.


In their usual fashion, the pair in SW-up had a much later start, with the first bird heading out at 9.29am. It returned at 10.14am and the second bird left for the first time in the first change-over of the day. There was one more change-over during the morning at 10.14/10.17am and then three more during the afternoon (11.54am/12.09; 2.58/2.59pm; 5.54/5.57pm).

This evening there was just one more change-over, at 7.46pm, and the bird that left during this exchange finally returned for the night at 9.24pm, the timing suggesting that it returned with the pair from the other box.

At no time today were the eggs in SW-up left unattended.




29 May - A better day. Sunny periods became more frequent as the day progresses, although The temperature reached 18C before lunchtime but fell away a couple of degrees as the afternoon progressed.

And it seems the better weather has had an effect on the occupants of SW-le -

It was the female who headed out first this morning, at 4.45am, returning at 5.14am. The male didn't go until 8.34am, and he stayed out for longer. His return at 10.03am, complete with a feather, prompted the first change-over of the day.

Since then there has been one of the pair in the box at all times, with four more change-overs taking place before the end of the afternoon. The last of these involved the male returning at 6.01pm and his partner leaving two minutes later.

The male continued to sit on the eggs for the next three hours, apart from a couple of moments before 9am when he looked out briefly. Finally he couldn't wait any longer and left at 9.12pm, leaving the eggs unattended for the first time today. he returned at 9.28pm. It means that the eggs in SW-le were left unattended for just 16 minutes today. Are they still viable? Was this a strategy by these Swifts to hold up development until the weather improved? We shall see....


The Swift pairs and their eggs this evening, 29 May

In SW-up the first bird headed out at 8.28am, returning for the first change-over at 10.28am. Between then and 9.14pm there were just three more change-overs before the resident bird suddenly decided to head out, so that we had the situation where both clutches were left unattended.

One of the pair returned at 9.22pm, and the remaining birds from both SW-up and SW-le returned simultaneously at 9.34pm.




30 May - On a day which started off quite bright but became overcast and with drizzle, it has been the closest yet to similar behaviour in the two boxes.

As usual it was in SW-le that the day started first when the male made his first trip out at 4.54am, and when he returned 19 minutes later the female popped out for 15 minutes. After that there was a pause before the male left once more at 7.54am.

That marked the start of the day's sequence of change-overs, six occurring before the male left the nest at 6.24pm. This time the pattern was broken when the female left the nest at 9.07pm, leaving the eggs unattended until she returned 16 minutes later. Her partner arrived at 9.26pm to end the day's activities.

In SW-up the day started with the first of the pair leaving at 6.25am and returning 9 minutes later, but it was 8.21am before the second bird headed out. When this one returned at 8.36am the first of the day's six change-overs took place. The final departure took place at 8.52pm, with that bird returning for the final time today at 9.26pm, simultaneously with the male from SW-le.



31 May - A bright, sunny morning with the temperature 8C at 7am.

That cold start had the Swifts in SW-le taking a 'lay-in' this morning, with the male not leaving the box until 7.34am. The first change-over of the day took place at 7.51/7.55am, with the female returning just ten minutes later. The pair stayed huddled together for the next twelve minutes before the male left again.

After that, the female had to wait until 11.20am before she was relieved at 11.21am. During the rest of the day there were three more change-overs and in the evening there was what is becoming the usual sequence whereby the male left at 4.48pm after a change-over and when he hadn't returned by 8.36pm the female left too. This time she was gone for just nine minutes. The two birds returned at 8.45pm (m) and 8.53pm (f), but she only stayed for three minutes before leaving again, and the male left too at 9.16pm. This time the eggs were left unattended for eighteen minutes before the pair returned at 9.34pm (m) and 9.36pm (f) to end the day's activities.

In SW-up the first departure took place at 7.23am, with that bird back into the box six minutes later. There was then a pause of 22 minutes before the second bird headed out. This Swift didn't return until 11.32am when the first change-over took place.

During the rest of the day only three more change-overs took place, the final one at just before 8pm. However, at 8.53pm the resident bird also left, leaving the eggs unattended for the next 31 minutes before the pair returned at 9.24pm/9.33pm to settle for the night.



- Click on the images to see larger versions -

2011 Nestbox Diary Index .......... .........................................................  ..June (part 1)