Population models give insights into effects of wind farms

As a first step, an estimate is made of the consequences of the intervention on mortality and/or reproduction. Subsequently, it is important to test which effects can be expected at the population level. These effects at the population level can be tested using population models.

We carry out such analyzes within various projects, both for onshore and offshore wind farms. An important method here is the use of matrix models.

Within the Wozep programme (Wind Op Zee Ecological Programme, Rijkswaterstaat) we have developed population models for species that are sensitive to the effects of offshore wind farms. This includes the effects of collisions with wind turbines and the effects of habitat loss, and for both local seabirds and for migratory birds.

We have made use of matrix models to assess the development of a population on the basis of species-specific survival and reproduction figures. By adjusting survival for the additional mortality resulting from the impact, different wind farm scenarios can be compared. This can be applied in the cumulative calculations of all planned wind farms in the southern and central North Sea for the cumulative effect assessment project - KEC 4.0.

Within KEC 4.0, in addition to the scenario without impact of wind farms (null scenario), a number of scenarios with impact were calculated.
At the national scale, the planned roll-out of wind farms up to 2030 has been calculated (base scenario), as have various expansion variants. In addition, the effects on an international scale has been calculated; this scenario consists of the national base scenario plus the international wind farms with a planned realization until 2030.

In order to subsequently determine whether a modelled impact is acceptable, a threshold value is required. These are policy choices, which are made by policymakers on the basis of the framework for Acceptable Levels of Impact (ALI). This ALI method was developed by Waardenburg Ecology in collaboration with Wageningen Marine Research.

With the help of these impact assessments, we can provide insights into the extent to which offshore wind farms influence bird populations.