The 2008 Nestbox Diary

 April - part 3

Incubation time 

Go to the last entry on this page                   Go to previous entry

18 April - With both families now incubating their eggs, the next week or so of relative quiet gives me a chance to get some other things done around the house, garden and caravan, and there may not be daily diary entries, unless something interesting, or untoward occurs.

This morning, as planned I took advantage of the Starlings' absence to clean the camera lens (how well remains to be seen this evening, if the sun shines by then). Once that was done I took advantage of the moment to take what will probably be my only photograph inside the Starling box.

The Starlings' five eggs, photographed this morning


A lovely shade of blue, and with no markings, the shiny eggs measure about 30x21mm (BTO Bird Facts), and as you can see, the grass-type leaves have been fashioned into quite a smooth nest cup for them.


The Starling and Great Tit eggs compared


I also took another photograph of the Great Tit eggs this morning (again not the whole clutch in sight), and I thought it might be useful to compare the two clutches.

Here, I've combined the two images at the same scale, with a Great Tit egg just under two thirds the length of the Starling egg.


At 7g, one Starling egg is some four times heavier than that of the Great Tit. With each Great Tit egg weighing just 1.7g, that clutch of ten eggs has a total weight of around 17g, compared with 35g for the five Starling eggs.

Perhaps at this point I should make it clear that before approaching the Starlings' box I waited for a time when both birds were not only out of the box, but had left the vicinity of the garden completely. Also, I now have a time-lapse digital recorder (eBay!) as part of my monitoring set-up, and it has the facility to provide live images on my laptop via the wireless network. This meant that I could have the laptop out in our driveway while I got things ready, and then check the box before going up the ladder, just in case a Starling managed to return unseen by me.

From now on I will also be using the laptop in this way to check the Great Tit box before I go into the viewing tower.

Over the last two days the weather hasn't been kind to any nesting birds. The temperature hasn't managed to reach 10C, and a strong north-easterly breeze has made it feel even colder. The forecast suggests that it will be colder with some rain tomorrow.


19 April - A promised, it has been a miserably dreary day, with light rain for much of the time and the temperature failing to get above 8C.

There are no photographs today, but here are a few details of the Great Tits' day -

The female left the nest for a total of 102 minutes during 14 trips out, the first at 6.38am. Her longest absences were at 12.37pm (14 minutes) and at 5.33pm when she was out for 15 minutes. Her final trip out (lasting 7 minutes) came to an end at 7.08pm.

The male visited her in the nest some ten times, plus one when the female was fed at the entrance. Most of those visits occurred in the morning and early afternoon, with only one after two o'clock.

On several of this visits he brought in quite large caterpillars and rather than simply passing them to his partner he held on while she pecked at them several times before actually taking them.


22 April - With everything going according to plan in the boxes I've been taking the opportunity to get other jobs done.

However, over the last couple of days I have taken advantage of the female Great Tit's absences from the nest to set up my Olympus E20 camera so that I can take photographs of her in the nest remotely. That camera was chosen because while it gives lower resolution images than my Canon cameras, it has a much quieter shutter. A long shutter release cable reaches form the camera and into the now empty log shelter where I can hide away and set up my laptop to watch the live image of the nest.

Today it has been sunny, and with the temperature over 11C by 10am and reaching over 17C this afternoon, the female seems to have been out of the nest quite a lot today (I hope to check the video later this evening). Nevertheless I decided to test out the camera arrangement. for the first time.

Female Great Tit returns to her nest


Unfortunately, I chose to do this during the afternoon while she seemed to be out more than in, but this is her as she returned from an excursion.



Female Great Tit sitting on her eggs - 1



I had already operated the camera on its own to monitor her for any reactions. She seemed to ignore it and when both the camera and flash were used this afternoon she settled into another spell on the eggs as if nothing had happened.


Female Great Tit sitting on her eggs - 2


A few minutes later and she had turned and settled even lower.

I'm sure that she can see the spiders that occasionally move across behind the glass and appear on the webcam images. There are quite a few Pholcus phalangioides living in that area, and I have to brush away their webs nearly every time I climb up into the box.


I had hoped to capture one of those moments when the male Great Tit would bring food in for his partner, but that didn't happen during the time I was watching today. At least I was able to confirm that the arrangement works well without causing stress to the female, and I will be trying again to photograph the feeding over the days to come.

This evening I've gone through the recording for the day and come up with the following - Between the first time that she left the box at 6.12am and the last time she returned at 6.58pm, the female Great Tit left the box 19 times today, for a total of 218 minutes. That is over twice the time that she was away from the eggs on the 19th when the temperature didn't rise above 8C. Her shortest excursion today lasted 6 minutes, and the longest, at 1.07pm was for 24 minutes.

The male only entered the box four times today, three in the morning and then  at 4.09pm.


24 April - No photographs today, but at last I have some details of how the two Starlings shared out incubation duties during the day.

The female left the box for the first time at 6.05am, and as soon as she departed her partner took her place for his first turn of the day. After that there were a further 24 changeovers during the rest of the day, with the male leaving for the last time at 6.31pm.

Between 6am and 7pm the female spent a total of around 325 minutes on the eggs with a longest period of 59 minutes during the afternoon. The male spent less time, about 279 minutes in the box. His longest stay was for 50 minutes, just before his partner had her 59 minute session.

While nine of the changeovers saw both birds in the box for a few seconds, in most cases one partner left before the other bird entered. Only on six occasions were the eggs left unattended for more than a minute. Five of those times ranged from 2 to 4 minutes. However, in the late afternoon they were left for nearly 17 minutes. This last period coincided with my chopping wood in the garden. Even with that extended period, the eggs weren't left unattended for more than around 35 minutes all day.


27 April - As we get closer to hatching in just a few days time I still haven't managed to get a photograph of the female being fed in the nest. If it's fine over the next couple of mornings I must try again. Otherwise, everything seems to be going well in both Great Tit and Starling boxes.

Swift high overhead



However, as reported yesterday in my garden diary, the Swifts are returning and this could mark the start of problems.





If you have been following my diaries for some time you will remember that I had put wooden blocks into the Swift boxes to prevent the entry of Starlings.

Composite image showing a Starling intruder in lower Swift box After spotting the Swifts yesterday evening I removed these blocks, and needless to say, after failing to get into the upper box (lower-left in this image) a Starling got into the lower box this morning. It spent a while inside, and seemed intent on destroying the straw ring.

Originally, that lower box didn't have an approach ramp, but I was advised to add one - this morning I removed it again.


This evening there is a Starling once again trying to access both boxes but with no success at to the present time(7pm), so my fingers are crossed. If I see that the Starlings are getting in then I may have no choice by to seal the boxes as they are too close to the Swift nesting site in my neighbour's roof space.

With the Swifts back in town I'm now not only trying to monitor both their boxes but also those of the House Martins (especially as I think I caught sight of one this afternoon).

A Collared Dove appears on the House Martin camera


There was a moment of excitement this morning when something appeared in the image from the external camera at the House Martin nests. As it turned out, it appears that a bird had decided to use the camera as a perch for a few moments.

This image suggests that it was a Collared Dove - I trust it won't decide to try and build one of its flimsy nests there!

Click on the images to see larger versions -

2008 Nestbox Diary Index..........Previous Chapter.......... April (Part 4)