This project is situated on a large greenfield site with surrounding woodland and is an ideal site for ground nesting birds. There is a need to locate and protect these nest sites and provide advice to the construction team. One of the contributing factors that influenced decisions to find alternate methods to ecological surveying and mitigation was the onset of coronavirus.
This led to restrictions on getting the ecological resource on site to carry out surveys so new approaches were investigated. The approach involved surveying for skylark nests on a 34-hectare greenfield site; skylarks are most common in arable farmland, making use of crops to provide the cover for nesting and bare ground for feeding.
Skylark populations have dramatically declined since the 1970’s mainly due to changes in agricultural practices and reduced areas of grassland to breed in. Skylarks are one of the most difficult birds to survey and accurately locate their nests. In a construction environment it is important to be able to accurately tell where nests are to exclude and mitigate appropriately.
Traditional observational surveys are invasive and can be inaccurate and may miss some nests or even result in damage to nests. A high quality, quiet drone was specified with hi-res optical and thermal imaging cameras. These are able to locate nests with minimal intrusion. The drone gives accurate coordinates of the surveyed areas and locations of nests such that exclusion zones can be put on CAD drawings and then inputted into plant GPS systems to let operators know when they are working near exclusion zones.
In all surveys, this methodology confirmed either the absence or presence of skylark nests or skylarks on the ground, this giving higher confidence in the methodology. In summary, in 3 hours of drone survey time (1 operator and 1 ecologist) 5 nests were found, compared to 1 nest found in 20 hours of survey time using traditional methods (2 to 3 ecologists per hour).
With the ability to more accurately survey and find nests in grassland area they were able to monitor nests with minimal disturbance. Additionally, when compared to the land area required for exclusion zones using traditionally surveying techniques, greater areas of land were available for construction works to progress thus reducing risks to program.
Monitor Report. Align Joint Venture. Hertfordshire. December 2020.