Environmental Engineering Reference
In-Depth Information
The female's 50 % kernel encompassed half as many turbines as the males.
The juvenile falcon's home range was the smallest and accordingly contained the
fewest number of turbine locations at all kernel levels relative to the adults.
Collision Risk
The model estimates the adult female and male falcons may collide with a turbine
within 4 and 5 years, respectively, after the turbines become operational. The results
for the juvenile falcon suggest that the period between potential collisions for a
juvenile female may be 50 years (Table
3
). It is worth noting that the analysis is
based on the home ranges of three birds only and may not refl ect those of other
falcons elsewhere within the species range. If the falcons at this site choose to nest
elsewhere, or environmental factors change and their home ranges also change, then
the collision estimates may alter for those individuals.
The analysis suggests that both adult falcons are at risk of collision with turbines
within a relatively short time frame of the wind farm becoming operational,
while the risk to the juvenile over a 3 month dispersal period is substantially smaller.
The adult male appears less at risk during the autumn/winter period than during the
summer monitoring period, probably because he spent more time away from the
wind farm during autumn/winter (Table
3
).
The overall effect on the long term persistence of breeding falcons at the site and
their productivity depends on whether an individual that collides is replaced by
another from the fl oating non-breeding population and that a pair of falcons remains
productive at the site. If one of the resident adults is removed by collision and is not
replaced by another falcon that subsequently pairs and breeds with the remaining
bird, then the presence of nesting falcons at the site will cease, but may resume if
falcons re-colonise in the future. If a falcon that collides is replaced by another
Table 3
Mean number of estimated mean number of collisions per modelled period and number
of years (1/mean collision rate) between potential collisions for the falcons radio tracked
Modelled
period
(months)
Estimated mean
(±standard deviation)
number of collisions
Estimated mean number
of years between
potential collisions
Individual/tracking
period
Adult female autumn/
winter 2010
12
0.24 (0.22)
4
Adult male autumn/
winter 2010
6
0.06 (0.05)
14
Adult male summer
2010/2011
6
0.20 (0.20)
5
Juvenile female
summer 2010/2011
3
0.02 (0.01)
50
