Cranes need peace and quiet of Gwent Levels, says RSPB
Common cranes are breeding on the Gwent Levels for the first time in 400 years but the RSPB fears the habitat they need could be at risk from the proposed M4 relief road.
A pair of the long-legged birds broke off from a flock across the Bristol Channel to lay their first egg last year.
The RSPB said the revelation, in a Welsh Government ecology report, was emblematic of wider environmental concerns about the scheme.
A five-month public inquiry into the plans begins on Tuesday.
Those who want the road built said it is essential to ease congestion around Newport and boost the economy.
Damon Bridge, from the RSPB, who manages the charity's Crane Project, told BBC Wales environment correspondent Steffan Messenger the birds need peace and quiet to thrive.