Sunday, 18 July 2010

The Swift.

Swift Simon Hawtin

I became even more interested than I already was in the Swift when I saw the report of almost 21,000 past Spurn on 4 July, another interesting record I found is that of an early bird seen in Skelmersdale on 1 April 2004.

As elsewhere in Britain there is very little detailed knowledge of the Swift in our area particularly of populations, 10 years ago the breeding population was estimated at 2,000 pairs with urban regeneration and housing modernisation continuing to take its toll, another example is the demolition of the East Lancashire cotton mills in the last quarter of the 20th century.

The Swift has some interesting and often mind boggling behaviour not least being that it spends a large amount of its life on the wing and is unique in this country in that non-breeders don't come to ground during the whole of the summer, and furthermore it is even possible that most Swifts spend the whole winter in Africa south of the Sahara on the wing. Autumn migration from Britain begins soon after young have left the nest, but at the other end of the migration period there is the record of a bird remaining early into November when it then died. After leaving the nest the young receive no parental care and observations have shown that in fact they leave whilst the adults are absent though the adults themselves continue to roost in the nest for up to four days after the young have left. In one interesting case a study found that a young bird which left the nest on 31 July was found dead four days later 1,300km south in Madrid, the same study revealed that the parent birds were still roosting in the nest on the day the young bird had been found in Spain, the study further discovered that this had been the the fastest movement of a fledgling Swift from its nest site.

The Swifts dependence on aerial insects means that in bad weather non-breeders make long movements in Europe and at such times may be quite frequent, and - dependant on the severity of the weather - be for up to 2,000km. However, breeding birds tend to return to the nest at least three times a day even in bad weather conditions.

It is a know fact that the Swift cannot be sexed even in the hand, therefore nothing is known about any differences in timing and extent of migration between the sexes, but suggestions are that the sequence of leaving is failed breeders, followed by breeders, in turn followed by non-breeders.

The species is a hard bird to census and little is known about their status, but some reports indicate a decline not only by the earlier mentioned regeneration and housing modernisation but also that some aerial plankton on which they are dependant may be becoming less plentiful with a study showing that 15 major groups of prey have declined by an average of almost 50% representing serious problems for the Swift especially if the decline continues.

Meanwhile, whilst the weather stays like it is today in our area with persistent rain and being much colder, my personal concerns for the Little Ringed Plovers at Conder Green - which are trying their hardest to start a family - are become increasingly more intense, but it was still on the nest when I especially called there last evening in anything but ideal conditions.  


Warren Baker said...

Another sad situation. It can be remedied by a bit of sypathetic building work, just use the Swift bricks!

Richard Shilling said...

Thanks for posting this Pete. I think it is always worthwhile (at least for me) to read some history and detailed background on your days off from birding, I find it very interesting.

But a question for you that I've been pondering for a while. How on earth is it possible to count bird numbers into five figures, especially when it is as fast moving as a Swift? How exactly do the counters go about this?

Brian Rafferty said...

Pete. Another fascinating account on your blog. The swift really is an incredible bird and it seems to be here one day and then the next day they have all gone !!

Hope the LRP's at CG survive the current " Autumnal " weather.

Pete Woodruff said...

Thanks for comments Warren/Richard/Brian.


Needs a detailed reply re counting, about which I have many questions myself. An answer will be in your inbox soon - too long for on here - but busy at the moment so please don't hold your breath.


Trying to be realistic about the CG LRP's and its not looking good at the moment as I see it.