A project aimed at encouraging one of Britain's rarest birds to breed has begun in North Somerset.
The nests would often be swamped when lake levels rose
Bristol Water said bitterns were close to extinction in the UK 10 years ago, despite regularly nesting at its Chew Valley Lake reservoir.
Their nests kept being swamped when lake levels rose in early spring.
The company is extending its Herriotts Pool nature reserve adjoining the lake to create new reed beds and a constant water level.
"Bristol Water is negotiating ownership of an extra 2.75 acres of neighbouring land", said a spokesman.
"The plan is to dig out channels connecting it to Herriotts Pool. A mix of pools, channels and drier areas would be created and planted up with reeds.
"This would link up to another similar reed pool area Bristol Water created some years ago that proved too small on its own to attract nesting bitterns."