Extra safety measures are being taken to reduce the chances of swans flying into overhead power lines, which can kill or injure the birds.
Thousands of swans migrate to the Fens each winter to escape snow and ice that covers their Arctic breeding grounds.
The biggest concentration of swans is around the wetlands of the Ouse Washes, an important roosting site for both whooper swans and Bewick's swans.
But the swans don't just make use of the wetlands. Surrounding arable land provides vital feeding grounds to keep the birds fuelled up through winter.
Flocks of swans can often be seen feeding in fields on the left-overs from harvesting sugar beet, potatoes and cereals. This means that at least twice a day the swans make the journey from one site to the other by the most direct route possible.
Co-operative working between WWT Welney Wetland Centre and UK Power Networks is helping identify areas where birds are at risk from high-voltage power lines.
Leigh Marshall, Centre Manager at WWT Welney, said: 'Swans change the sites that they feed at throughout the winter season, as new sources of food become available. This in turn alters where they come in to roost, so the partnership between WWT Welney and UK Power Networks is of long-term importance, as the flight patterns of swans shift across our area.'
Kevin Pettit, who helps plan power line routes for UK Power Networks, says: 'We work closely with WWT Welney to identify flight routes that are experiencing problems each season and install bird flight diverters to help prevent birds flying into power lines. More bird flight diverters are being installed in priority areas this month. The latest bird diverters have spinning reflectors, with glow-in-the-dark panels, which makes them more visible for a time after dusk, when swans are more likely to collide with power lines.'
UK Power Networks has also identified sections where replacement of the lines with new covered wires will help birds.
January is the peak month for swans wintering in the UK, counts conducted on the Ouse Washes show that 7,885 whooper swans and 2,813 Bewick's swans roosting at night. In the next few weeks the swans will be preparing for their spring migrations to Iceland and Artic Russia.
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