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Saturday, 31 March 2012

2012: Will Bird History Repeat Itself?

Here we are again, a new year, a new spring, hopefully no new territorial fights.
I fear that bird history too has a tendency to repeat itself. Great Tits vs. Eurasian Tree Sparrows.

But let me go back in time in bird history....

I removed the Sparrows' nest not too long ago. The delay due to our very long holiday. Sparrows had obviously visted the nest and I decided, for fear of parasites, to remove it. And so I did. Sparrows visited the nest again. I cannot say for certain if it was the female or the male, but if the past few years of bird-watching have taught me something, then we could continue bird history on the assumption that it was the male Sparrow. I never saw the two birds together in the nesting box. But the male brought twigs inside the box and called insistingly to the female. This happened on Tuesday and ever since Sparrow visits and sightings have been reduced in number.
At the same time, Great Tits have been visiting the nest: the male jumping in, calling to the female and flying out once she has entered.

Some of you may recall: last year the Great Tit female had being building since about 4-5 days when Eurasian Tree Sparrows decided they wanted the nest. Sparrows are no match for the Great Tits and thus, after a quite violent fight, the Great Tits were forced to retreat. They did not give up the nest so easily, returning every day to check, but the Sparrows would not give way.

So will bird history repeat itself. I sincerily hope not. I enjoyed observing the dynamics of Sparrow nest-building, brooding, feeding, etc. but I would like to have a chance of re-observing these same phases with the Great Tits. The differences between the species is immense and fascinating.

I have only one other nesting box (NB-4) this year in my garden. The opening hole is 28mm in diameter. I had hoped for Blue Tits, but so far no sign of them. If no Blue Tits show any interest, and if bird history is to repeat itself, then I will change the front covering of NB-4 to one with a 32mm hole and thus hopefully have a fall-back nesting box for the Great Tits.

Here is the happy couple:

The male is quite diligent and has already fed the female while she was busy building the nest.

Side note: I am designing my very own self-sustaining nesting box (I will talk in more detail about it as I go), and am considering having a 30mm entrance hole. I wonder if that is small enough to allow Great Tits to enter but to stop Sparrows from entering.

2011 Nesting Box Timelines

2011 Events in Nesting Box #1 (NB-1)
2011.05.14 - Hatchling eyes are "slit"-open
2011.05.09 - Hatchlings present (chirping heard!)
2011.05.08 - 1st observed worm transport in nest
2011.04.26 - 1st night in which Tree Sparrw sleeps in nest (hypothesis: brooding has started)
2011.04.11 - Eurasian Tree Sparrow nest building
2011.04.11 - Disputes between the Sparrows and Great Tit occur in tree next to NB-1
2011.04.10 - Great Tit female returns to NB-1 but Tree Sparrows defend overtaken NB-1
2011.04.09 - Tree Sparrows attack Great Tit female and overtake NB-1. Sparrow start nest building over Great Tit nest
2011.03.31 - Great Tit female starts nesting bulding

2011 Events in Nesting Box #4 (NB-4)
2011.05.14 - Great Tit females still spends considerable time in nesting box during the day but no eggs laid so far
2010.04.22 - Great Tit female sleeps in nesting box for the 1st time (i.e. hypothesis 1 egg layed)
2010.04.21 - Switch NB-2 body to NB-4 body for optical (camera) access. Great Tit female continues to build nest.
2011.04.18 - Placing of NB-4 and almost immediate start of nest building by Great Tit. Sparrows acknowledge existence of nest (no attacks witnessed).