Tuesday, 28 April 2015

BirdBox2015: we wait patiently

Our female blue tit has been sitting on her clutch of eggs for 5 or 6 days.


So it may be another 9 or 10 days before we start to see chicks breaking out of their eggs and demanding to be fed.


That is assuming that the local predators don't carry away mum or dad first!

It has been an unusual season so far. From previous years we have noticed the female stay in the nest for a number of nights, and produce a similar number of eggs (i.e. one per night).

But this year the female spent her first night in the box on the 9th April, and didn't start incubating her eggs until around 23rd. That would have been enough time to have laid about 14 eggs.

The 50mm diameter window is letting in plenty of daylight

She also made a good job of covering them up. We only caught a glimpse of any eggs on the 22nd, and later that day were able to count all seven eggs. We know now there are at least nine, and my guess is that she probably has 10 in total.


So they are now running about 7 days behind my prediction and about 17 days later than what we have seen in previous years.

It is interesting that the BTO blue tit blog suggests that chicks usually hatch at the end of May. I wonder if this is some kind of British average.

The sky-light


Now that the female has settled, I've peeled back the black plastic which I had used to cover the 50mm window. This does not seem to have upset the parents or changed their behaviour in any noticeable way. But it certainly reduces image "noise" and improves the quality in any photos or video clips.

The predators


While there are certainly as many pesky cats patrolling our garden this year, its the sparrowhawk(s) that seem to be posing the biggest danger.

Last Wednesday I detected something moving in my peripheral vision, but looking up, all seemed quiet in the garden. I was just about to resume whatever it was that I was doing when a male sparrowhawk rose up over the pergola and then down again in a sort of tilted circular orbit.

As it appeared again I realised it was circling the shrubs around the bird box, and was trying to scare one of the tits out into the open.

Two strides to the back door and the sparrowhawk came around for the third and final time. It sized me up before deciding to exit the garden and seek his lunch elsewhere.

Once again today, I entered the conservatory and must have disturbed a sparrowhawk, as I saw him launch his self, fly low across the lawn, and then climb to clear the trees at the bottom of the garden.

All that was left of a goldfinch after a sparrowhawks recent visit

I just hope our nesting pair can evade capture (...at least for a couple of months).

video



2 comments:

  1. Great stuff. Still no interest in my box. Plan B and better luck next year. I'm coming around to the thought that although side-view boxes may give an alternative perspective, a top down view really does give a nice view of the eggs & chicks when v small. In my immediate region there's a great tit box with ?6 chicks all recently hatched since approx 1 week, and a blue tit box currently with 7 eggs. Interesting to see differences between pairs & timings.

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    Replies
    1. Sorry you have had no luck, maybe next year.

      Yes, I agree about the tilted box view. We can only see 6 or 7 of the 9 (possibly 10) eggs most of the time, as the others are hidden due to the viewing angle.

      So maybe next year I'll mount the box on a rotating mount. Start them off vertical, then rotate a degree or two each day as the chicks get bigger. (...there is probably a law against that!)

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