Creation of bog pools
Black-tailed godwits, redshanks and other birds can only live where they can find sufficient food for themselves and their young. The long, thin beaks of these wading birds are designed for poking around in the soil to dig up tasty small animals. It is therefore easy to understand why these birds struggle to establish themselves on dry, hard soil, solid rubble or completely asphalted areas. Wading birds also stay away from densely overgrown areas with tomentous (felt-like) vegetation.
Damp, open, “pokable” soil is also essential for grassland bird habitats. Creating bog pools should help to establish these important conditions, as a bog pool is not a waterway but a shallow trough that is only filled with water in spring and early summer during the grassland birds’ breeding season and whose soil is at least waterlogged. Most bog pools run dry later in the year. Another typical feature of these pools is that they are completely integrated into grassland areas and thus are also used for agriculture, usually for extensive grazing. This last feature is a key reason why the bog pools are not overgrown, as open soil is optimal for airborne seeds that take every opportunity to germinate, even on floodplains!
Ten of a planned total of 15 bog pools were completed initially during a first construction phase in October 2016. One year later, the remaining 5 bog pools were created – together with an „extra“ of 2 additional ones; due to a smart budget management it was possible to exceed the target!
Ranging from 900 to 5000 m² in size, the seventeen depressions also differ in shape. The excavated earth was arranged into very flat embankments at the edges, intended to add structural diversity and retain fast-draining waters after floods. The topsoil was removed before excavation and replaced afterwards. Planting of grassland vegetation appropriate to the site ensures that even a few weeks later very little hints at the tons of earth recently moved here. Small wonder, as the bog pools are just 20 or in a few places 30 cm deep.
One of the 17 bog pools differs markedly from the others. Instead of (humid) grassland vegetation, phalaris arundinacea was sowed at its edge. This low-growing reed species already thrives here and we hope it will continue to do so. We also hope the increased humidity resulting from the lowered ground level will encourage a neighbouring patch of common reed to spread and expand. So while 16 pools mainly serve to optimize the habitat for waders (such as black-tailed godwit, lapwing and redshank), the tenth is aimed at helping marsh harriers, reed warblers and other reedbed species.