Showing posts with label sand martin. Show all posts
Showing posts with label sand martin. Show all posts

Sunday, 19 December 2010

Signs of the Times: Autumn #4


More comparisons between the British countryside of today and that from 1959-1961 in the paintings of Charles Tunnicliffe in the Ladybird "What to look for..." series of books.


"...Then in a wailful choir the small gnats mourn
Among the river sallows, borne aloft
Or sinking as the light wind lives or dies;
And full-grown lambs loud bleat from hilly bourn;
Hedge-crickets sing; and now with treble soft
The red-breast whistles from a garden-croft;
And gathering swallows twitter in the skies."

John Keats (from “To Autumn”)
 
(Copyright: Ladybird Books)


Autumn Picture 4
A bit of a shorter account this time around as there are no species featured here that I haven’t already written about in this blog series. Nevertheless, here is another attractive Autumn image to enjoy; it does seem like ages since we saw the swallows, house martins and sand martins massing on wires and roofs in preparation for their southward Autumnal migration. In reality it was only a few weeks ago (maybe early-mid October here in Stirling?) when the last birds finally headed off on their long, risky journey to the heat and relative comfort of sub-Saharan Africa, wherethe food supply of flying insects, unlike in the Britishwinter, isn't jeopardised by low temperatures!

I have already posted, in some cases quite extensively, on the three related species, the swallow (Hirundo rustica), the house martin (Delichon urbicum), and the sand martin (Riparia riparia). In all three cases, I reported on a variable recent history for these species, which seems to be linked to the arrival or otherwise of seasonal rains in the Sahel and other sub-Saharan desert regions where these birds spend their time during the European winter. You can read more about the swallow in earlier posts here, a post including the house martin here, and I looked at the fate of the sand martin in Britain over the past 50 years here.


Perhaps it is the very obvious departure of these summer visitors, their “here one minute, gone the next” exodus that makes their massing for migration such a strong symbol of the departing warmth of summer and the ushering in of the shorter, colder days of Autumn. It always seems as if swallows and martins reappear much more gradually in Spring than they disappear in Autumn!

Looking forward to their return in 2011...


Monday, 3 May 2010

Signs of the times: Spring #12


More comparisons between the British countryside of today and that from 1959-1961 in the paintings of Charles Tunnicliffe in the Ladybird "What to look for..." series of books.


Spring would not be spring without bird songs."



Francis M. Chapman


Copyright: Ladybird Books

Yet another waterside scene for picture 13 from Spring, with a lakeside, or lochside picture full of birds. I’m falling behind a bit so I going to try a bit of a compressed post this time – similar amount of information but less time and space occupied! Here we have two nests – one built by a pair of mute swans, one by a moorhen or waterhen. The moorhen appears with chicks in the Summer book, so I will cover it there in more detail. The picture also shows a willow warbler singing from a sycamore tree, a common sandpiper at water level and swallows and sand martins skimming over the water, “hawking flies”.






Any following information on trends, plus the graphs above come from the British Trust for Ornithology. As you can see, the stories of the birds in the picture since (soon after) the Ladybird Spring book was published are very varied.


The Mute swan (Cygnus olor) population in Britain has risen pretty steadily since the 1980s (it was stable before then), according to the BTO: “perhaps reflecting warmer winter weather and the replacement of anglers' lead weights, which had earlier caused many cases of lethal and sublethal poisoning, with non-toxic alternatives”. While lead was still used for anglers’ weights, swans were found dead or dying with many, sometimes hundreds of lead weights in their digestive systems. Their method of feeding, upending and dabbling on the bottom of the water body, loaned itself to preferentially picking up lost lead weights. There is no specific information on population trends for Scotland’s Mute swan populations, nor any noted effects of climate change on egg laying dates for mute swans.


Mute swans probably deserve more space here than I can give them – all British swans are owned by the Sovereign, the inspiration for Henry the VIII’s Swan Barges on the Thames, the Swan Vestas matchbox anyone?, the subject of wonderful urban myths (I was, indeed, told as a child by my father, a man highly knowledgeable in the ways of nature, that a swan can break a man’s arm with its wings – it seems I wasn’t the only one to be told this, so this site made me smile. And the British media do love a good swan story – the latest being the so-called “asbo swan” in Cambridge which has been attacking rowers (no doubt it will prove to be an Oxford swan...), but I refuse to say much more about that given the amount of rubbish already written and spoken about it. The most ludicrous thing I heard about it had to be during a phone-in on Jeremy Vine’s show on Radio 2, where some damned clown actually bothered to phone in to say that if the swan attacked his kids, he would wring its bloody neck. He didn’t live in Cambridge; a) So don’t take your kids down there mate, and b) wring its bloody neck? I’d like to see you bloody try!


The willow warbler (Phylloscopus trochilus) is almost physically indistinguishable from the chiffchaff which featured in an earlier post. It is different in both habit and song though, and the two warbler species are very easily distinguished when singing. Unlike the chiffchaff, however, the willow warbler population seems to have undergone a significant decline in England and Wales, but with Scottish populations remaining unaffected. BBS [Breeding Bird Survey] figures since 1994 indicate a stark contrast between an initially upward trend in Scotland and in Northern Ireland, and continued severe decreases in England and in Wales. Pressures on migration and in the winter are likely to be affecting the population, as is a reduction in habitat quality on the breeding grounds [presumably not the Scottish ones though]”. It does look like we don’t know exactly what we are doing right for willow warblers in Scotland. The BTO reports that average egg laying dates for this species have become a week earlier, “perhaps in response to recent climatic warming”. Also, the trend down south is more widespread as numbers “have fallen widely across Europe since 1980”.


The Common Sandpiper (Actitis hypoleucos), the small wading bird bottom centre of the picture, is a favourite bird of mine, which I associate with upland burns in Scotland, where its insistent, high-pitched call while bobbing up and down, flitting between river stone perches is one of the best sounds and sights of summer for me. At this delightful website, you can hear a selection of the songs of the common sandpiper. Only the size of a starling, its range covers more than half of the world. Unfortunately, however, like the willow warbler, it seems to be suffering badly in the UK and across Europe. The BTO reports that decline from 1985 onwards (after a more gradual increase) “has yet to be explained.” So that’s that. Hard to do anything about it if you don’t know the cause! The common sandpiper is one of the species that tried to lure predators away by feigning a broken wing when its nest or chicks are threatened. For a more emotional view of the common sandpiper and its ability to inspire, you might read “The song of the sandpiper”, the autobiography of the late John Morton Boyd, a pioneer of nature conservation in Scotland.


Finally for now, swallows (Hirundo rustica) and sand martins (Riparia riparia), seen skimming over the water here, catching insect prey. One swallow does not a summer make, so they say. But the arrival of the first swallow is such an iconic late Spring event for nearly everyone I know. Maybe we all hope that they will bring a bit of African desert heat with them from their African over-wintering grounds. For swallows, the data provided above are for England and you can see there is quite a lot of fluctuation, thought to result from variation in rainfall in the western Sahel prior to the swallow’s Spring migration north through West Africa – wetter conditions mean better survival. But what has happened to the swallow populations in Summer in the UK is also complicated. The BTO explains that “It is likely that, in eastern parts of the UK, the loss of livestock farming and grazed grassland, together with arable intensification, has caused the Swallow population to decline, while an increase in the area of pasture in the west and north has promoted a population increase which apparently has more than compensated for declines elsewhere.” The swallow has, however, been awarded a warning Amber status in the UK, on account of its decline across Europe.


The Sand Martin population shows similar levels of fluctuation to those of the swallow across the time since the Ladybird books were produced. The BTO and (my posh bird book) "The Birds of the Western Palae-Arctic (Concise Edition)" both indicate that, as with swallows, these fluctuations are likely to be the effects of variable rainfall in their over-wintering grounds in the Sahel in Africa (“Rainfall in the species' trans-Saharan wintering grounds prior to the birds' arrival promotes annual survival and thus abundance in the following breeding season”). But the sand martin is a difficult species to assess accurately, as its often-large nesting colonies are formed in unstable sand cliffs of river banks or quarries, etc, that can disappear (or be abandoned) between years. There does not appear to be any long-term trend in the UK, however, although there is concern over an apparent decline since the late 1990s.


The tree featured here, the sycamore, also appears later in the year, in another book, so I am going to defer comment on that until then.