For decades, the arrival of the first V-shaped flights of Bewick’s swans in Britain’s wetlands after a 2,000-mile journey from Siberia heralded the arrival of winter. This year, a dramatic decline in numbers of the distinctive yellow-billed swans skidding into their winter feeding grounds could be the harbinger of a more dramatic shift in weather patterns: global warming. Ornithologists at the main reserves that host the birds, the smallest of Britain’s swans, said only a handful had appeared on lakes and water courses. Normally, there would be several hundred. The latest arrival in a decade of Britain’s seasonal influx of 8,000 Bewick’s swans throws into sharp relief the debate on the effects of climate change as it enters a crucial week. As the Government’s forthcoming Climate Bill is finalised, Sir Nicholas Stern, a former World Bank economist, is expected to warn in a report on Monday that failure to tackle global warming will provoke a recession deeper than the Great Depression. But far from Westminster, the potential ecological impact of the same phenomenon was being noted in the absence of the high-pitched honking call of Bewick’s swans on reservoirs and wetlands from the Ouse to the Severn […]