July 21st- problematic tree sparrows and swift diary

We have with a very large population of tree sparrows in Gilling. Now don’t get me wrong, I love tree sparrows and they are a favourite sketching subject. We were lucky to have a pair nest in our garden in Hungerford when I was a child. I remember realising one day with my new binoculars that they were tree sparrows, not house sparrows and felt so privileged to have them in our nest box. I would hazard a guess that having a tree sparrow nesting in a Berkshire garden now would be something of a mega sighting. But here in Gilling we have had an unpaired male in the garden throughout spring and summer that has caused almost constant hassle to other species.

In May it sat on top of the blue tit’s nest box relentlessly, stopping the parents from feeding their young. They only fledged three in the end. This may or may not be due to the tree sparrow, but certainly the blue tits were inconvenienced at best and the young were fed much less than they should have been. Interestingly the nest box had a 25mm hole so the sparrow couldn’t get in anyway! I have heard of another identical case in a nearby garden.

Meanwhile the swifts arrived. I always plug the nest box entrances before they arrive to prevent sparrows from taking over and provide eight nest boxes for tree sparrows. Three or four pairs nest under our roof tiles too. But come second brood time all the nest boxes are deserted and they go for the swift boxes. Not only do they go for the swift boxes, they go for the swifts, launching themselves at swifts in flight or attacking them when they prospect. The only way to prevent this is to shoo them away or stand below the nest boxes. They are more shy than swifts and won’t come near if I stand below. But I can’t do this all the time!

So the tree sparrows’ first brood boxes remain empty for the rest of the season and they begin the battle with swifts. But this year there has been a new problem. Regular readers will know we attracted a pair of house martins. No words could describe my elation at having these wonderful birds tucked up in a brilliant Schwegler nest box. But, enter our unpaired tree sparrow; they have been subject to almost constant harassment. The tree sparrow chases them when they leave the nest box, sometimes striking them in the air. A friend recently had a whole clutch of house martin eggs destroyed by tree sparrows and I have previously witnessed this too so we are on tenterhooks. As I write he is sat just above the martin nest. His harsh chirping is constant from dawn to early evening. I have shooed him away hundreds of times but still he returns. This morning he flew almost vertically up from the roof and launched himself at a swift.

Whilst frustrating and worrying it is fascinating to ponder the behaviour of this and other tree sparrows. So much of what it does seems to be born out of pent up frustration. It should be constantly busy feeding young, perhaps even raising a third brood by now. Why has this bird not found a mate I wonder?

As I mentioned the population of tree sparrows here is very high. In all my life I have not seen a more abundant bird in a garden at all times of the year. Considering it is a scarce species in many areas I wonder if someone is writing a PhD on why there are so many in parts of North Yorkshire?

Tree sparrows will undoubtedly be a benefactor of swift box schemes in this area, perhaps the main benefactor? I remain far from convinced that swifts will usurp them once the sparrows are established. Every inch of a swift box is packed tight with material, leaving just a narrow tunnel to a tiny nest chamber. Of course we must celebrate a species that is doing well, but it shows that conservation is a very tricky balancing act. More tree sparrows could mean fewer house martins and possibly affect other species too.

Below. Unpaired male tree sparrow.

Below. Swifts screaming high above the village. An increasingly common sight the nearer we are to the main departure of swifts. Watercolour 340x470cm  £375(not including postage)




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