Camilty Wind Farm - Partnerships for Renewables

Camilty Wind Farm
12.5.49 Based on the observed flight activity, the collision risk model estimates 0.3 goshawk
collisions every year (as calculated using the recommended 98% avoidance rate for this
species – SNH 2010). This equates to one goshawk mortality approximately every three
years and four months and between seven and eight mortalities over the 25-year operational
life span of the proposed wind farm.
12.5.50 At the national level, the predicted annual collision rate would represent just 0.2% of the
breeding population (assuming all collisions were of breeding adults) and no more than 0.1%
of the total population (at least 130 pairs / 260 individuals - Etheridge et al. 2012) every three
and a third years.
12.5.51 At the regional (Border Hills NHZ) level, this collision rate would represent the loss of
approximately 0.5% (0.42%-0.54%) of the estimated Lothian and Borders breeding
population (28-35 pairs - Etheridge et al. 2012), if it is assumed that all collisions are of
breeding adults, and between 0.35% and 0.46% of the total estimated regional population
(65-85 individuals) every year. Over the life span of the wind farm, this would equate to
between 11% and 13% of the current Lothian and Borders breeding population and between
9% and 12% of the current total population (assuming maintenance of a stable population
across the region and the continued presence of a resident pair of goshawks in the Camilty
area over this period, the latter of which will depend on replacement of the breeding adults
that die, whether from collisions or other causes). In relating the level of predicted collision
mortality over the life span of the wind farm to the current population size, it is important to
bear in mind that goshawks are not particularly long-lived birds (see 12.5.52 below), so there
would be substantial natural turnover in the population during this period.
12.5.52 With regards to how this compares to natural mortality rates, Kenward (2006) reviewed
several population studies from Scandinavia, Europe and North America and found
background mortality rates to be 15%-21% in adults, 31%-35% in second year birds and
40%-42% in juveniles. The Border Hills NHZ estimated population of breeding birds of
between 28 and 35 pairs (56-70 individuals) would therefore be expected to have a natural
adult mortality rate of between one bird approximately every month or between 10 and 13
birds per year (based on an average adult mortality rate of 18%). This equates to between
33 and 42 deaths through natural mortality over the same period of time that it is predicted
that one mortality would occur through collision with the wind turbines at the proposed
Camilty wind farm (i.e. every three years and four months). Over the course of the life span
of the wind farm, this would be between 250 and 315 mortalities by natural causes,
compared to an estimated seven to eight mortalities through turbine collisions. If it is
assumed that all collisions at Camilty would be of breeding adults, this equates to an
increase of between 2.5% and 3.0% of the adult natural mortality rate. However, the
additional mortality of breeding adult birds from collisions is likely to be less than this because
some of the flight activity recorded at Camilty was of juvenile birds (see 12.5.48 above). The
additional mortality will have a proportionately smaller impact on the juvenile age class, given
the expected higher natural mortality rates amongst juveniles than amongst older age
classes.
12.5.53 It is considered that the number of goshawk mortalities caused through collisions with the
wind turbines of the proposed development would represent a small to moderate proportion
of the population at a regional/NHZ scale, compared to the background mortality rates. Any
effects on the population are therefore predicted to be of at most of medium magnitude, and
March 2013 12-48 ES Chapter 12
Ornithology
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