Swifts

I recently heard a discussion which started with the question: “What aspect of the place where you live do you enjoy, but did not know about when you moved there?” For myself, having moved to my house a bit over 9 months ago, there are actually quite a few things. But one is particularly unexpected. I am not really into ornithology [or bird watch or “twitching” as some people call it], but I do find natural history interesting in general. So, it is a surprise to find that some birds give me particular pleasure – they are swifts …

At first we were unsure exactly what the birds were. They swooped around at either end of the day and some were clearly nesting high up under the edge of the roof. We did not know whether they were house martins, swallows or swifts. A little research and we had the answer. The shape of the tail suggested swifts, but then I read that, of the 3 species, only swifts’ nests are not visible from the ground, so we were sure.

The birds swoop around the sky, feeding on insects. They periodically fly up to their nests, at great speed – clearly delivering food to their young. Although they only appear to be active in the morning and evening [when I assume food is on hand], my research makes me wonder where they are for the rest of the day. I wonder this because, apparently, swifts almost never land voluntarily – only briefly for mating etc.; they spend most of their lives on the wing and have only very small legs. Once a chick has left the nest, it may fly continuously for 2 years until it reaches sexual maturity.

We see the swifts from the garden and also from the upper windows of the house, where they appear to fly directly towards us before swerving up to their nests or away into the sky again. They are well known for their precision flying and very infrequent accidents. I wondered how they achieve such control. Another characteristic of swifts is their distinctive “song” – actually is is more of a screech. They make this sound as they swoop towards the house and I wondered whether they have some form of echo-location system, like bats. Again, I did some research and I may be right. It seems that there is a type of swift that lives in dark caves and they have developed just such a capability. However, I could not find any information about the Common Swift having echo-location. If you know otherwise, please comment or email.

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  • In wondering where the swifts (or swallows) go, you are in good company, not so much for the “between meals” period, but for the whole of the winter. Our British medieval ancestors had one theory that swallows spent the winter at the bottom of frozen lakes, only to emerge suddenly in Spring. A wonderful theory, spoiled now by our modern knowledge of migration. But perhaps the bottom-of-lakes theory could be revived for your “between meals” question?
    btw, my rule of thumb for distinguishing martins and swallows(or swifts): martins have big white bums (hope this doesn’t get censored, in which case… posteriors…), easily visible in flight.

  • Thanks for the input Hugh. I had forgotten about that old story about swallows.

    I have since been advised by an ornithologically accomplished friend that the swifts spend most of the day out in the countryside, where insects are more available near crops. Unexciting, but a credible explanation of their disappearance from the vicinity of my house.

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This article first appeared on the Siemens Digital Industries Software blog at https://blogs.sw.siemens.com/embedded-software/2011/07/14/swifts/