Saturday, 8 December 2012

BTO Conference


This week-end I am up at Swanwick in Derbyshire, attending the British Trust of Ornithology Conference, which is typical as flocks of Waxwings are clearly now invading Northamptonshire!  A short walk around the complex here at Swanwick was enough to find a single vocal Waxwing this morning!

Yesterday evening there was a superb and totally inspirational hour long presentation on the crusade to save the threatened Spoon-billed Sandpiper, and the extraordinary lengths and measures achieved already in bringing this enigmatic wader back from the brink of extinction.  Perhaps at least as important has been the clear definition and importance of saving what is left of the East Asian/Australasian coastal habitat, which is critical to the survival of many other waders too.

A significant part of the day today has been discussing and commenting on the preliminary results of the Bird Atlas 2007 - 11 and the mapping of Britain's and Ireland's birds.  It is anticipated that as many as 40,000 observers throughout the land participated in this study, including many in our own fair county.  Some examples of the results are as follows:-
  • The biggest positive change as a group was the egret family, with a range expansion and associated breeding of Little and now Cattle and Great White Egrets;
  • The highest density of registered observers was in urban Edinburgh and Belfast!
  • The Isle of White failed to confirm breeding of relatively common birds such as Tawny Owl, Common Buzzard and Greylag Goose!
  • 96 species on non-native birds were recorded (with Black Swans by way of example recorded in 100 squares);
  • Yellow Wagtails have suffered a 32% range loss and huge reductions in population density;
  • The first British breeding Cetti's Warbler was in Kent in 1973.  During the survey they were located in 421 km squares nationally in the breeding season and 375 during the winter period, reflecting a successful colonisation of England;
  • Due perhaps to climate change, the Hobby population has shifted 150km north since the last atlas;
  • Ireland has experienced some huge changes.  Positives include a high density of Wrens, a huge increase in Great Tit density and the natural colonisation of the green isle by Great Spotted Woodpecker.  Negatives are the virtual extinction of the Corn Bunting (and the range halved in GB), major losses in the Stock Dove population (but the GB population is stable) and a massive decline in the Curlew with 20,000 pairs in the 1970s now reduced to between 50 - 200 pairs!
  • Woodcock (there is a specific survey next year) have shown a winter expansion of 37% but a breeding range contraction of 55%;
  • The Kestrel is in decline across the whole of GB but with no range loss, just actual numbers.
Another presentation reflected on habitat and what exactly does a bird need?  Some of this was about comparables.  Why is it that in Germany Goshawks have moved in to the cities such as Berlin and Hamburg and breed in the parks and feed on urban birds successfully, but here they are a bird that is sensitive to human activity and can only normally be found in large tracts of forest/wilderness?  The British Willow Tit is associated with mature hedgerows, scrub and light deciduous woodland, but in northern Europe is a bird of conifers.  It also reflected on the findings of the Atlas in that birds such as the Redstart and Whinchat which have now seemingly abandoned the lowland areas of middle England during the last three decades and are now mapped to their habitat preference to the uplands of the West.  As predicted this presentation provided more questions rather than answers!

A further presentation which was well-received was the current findings on the long term study of the sea-birds breeding on the Isle of May up in the Firth of Forth.  It was entitled 'An Exultation of Auks', with a particular emphasis on the Guillemot and Puffin.  Irrefutable evidence was presented that showed that since the 1980s there had been a 3% increase in the sea temperature and in particular how this affected marine life and in consequence the food for the sea-birds.  It seems that the Lesser Sandeel which has been widely regarded as the essential diet of many sea-birds is quite rapidly disappearing and is being replaced by sprats or similar species.  This is associated with the reduced ability of the species of copepod to survive in warming waters (the staple diet of sandeels) and the increasing ability of the prey item of the sprat to sustain and exploit new waters.  This isn't the whole story but probably the main influence on the changing fortunes of at least some of our sea-birds.  Apparently Snake Pipefish have not been recorded as a prey items for Puffins etc since at least 2009, so this concerning period when they were brought in by our breeding sea-birds (they are of low nutritional value and mostly indigestible) appears to be over for the time being.

The use of miniature geolocaters and time depth recorders have been used in recent years on some of our auks, and although it is early days the initial results on post-breeding dispersal and the amount of time these birds spend underwater is fascinating (e.g. 50% of the recorded dive times of the Guillemot occur at night; Puffins seems to be only active during the daylight hours).

There is plenty more interesting info coming out of the conference but that will do for now!


Neil M

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