Predicting the Weather-Dependent Collision Risk for Birds at Wind Farms - Wind and Wildlife - page 3

Keywords Avian collision • Offshore wind farms • Modelling • Wind impacts •
Flight patterns
Introduction
A number of specific studies have been carried out on collision risk in connection
with onshore and offshore wind turbines (Garthe and Hüppop 2004 ; Desholm and
Kahlert 2005 ; Blew et al. 2008 ; Krijgsveld et al. 2010 ). Still, little quantitative infor-
mation exists on actual collision rates and collision risks, (but see Band et al. 2007 ;
Bellebaum et al. 2010 ; May and Bevanger 2011 ; Hull and Muir 2013 ) and knowl-
edge of the factors influencing the collision rates is limited. Factors that influence
collision risk can be divided into three categories: those related to the environment, to
the species, and to the configuration and location of structures (Jenkins et al. 2010 ).
Species-related factors include habitat use, body size, flight behaviour, age, sex,
and flocking behavior (Barrios and Rodriguez 2004 ; Drewitt and Langston 2008 ;
de Lucas et al. 2008 ; Smallwood et al. 2009 ; Prinsen et al. 2011 ; Martin 2011 ).
Although it is obvious that environmental factors like wind direction and speed as
well as landscape features influence collision risks, there is a paucity of studies
aimed at quantifying the effects of such external factors on avian collision rates at
wind farms. Here, we report on two post-construction studies from coastal Denmark
in which the influence of weather on the flight patterns of a range of bird species
was estimated using predictive models based on three-dimensional tracking of bird
flights and weather model data. Collision risks for the same species were determined
using collision models. The modelling methods are generic, and provided compre-
hensive tracking data are collected they may be applied in any study of bird interactions
with a wind farm.
Materials and Methods
Study Sites
Bird movements were studied during post-construction monitoring at two sites for
offshore wind farms characterised by very different bird communities; one in the
North Sea where resident (non-breeding) seabirds dominate movements and one in
the Baltic Sea where migrating landbirds dominate movements. Figure 1 shows the
location of the two sites. The wind farms in both sites are situated offshore. In the
North Sea, the Horns Rev 1 (HR1) and Horns Rev 2 (HR2) wind farms have been
constructed approximately 15 and 35 km west from the Danish North Sea coast
in 12-15 m deep water. In the Baltic Sea, the Rødsand 2 wind farm has been
constructed 5-10 km offshore. The resident wintering seabird community at Horns Rev