Tasmanian wedge-tailed eagle power line crossings

Avian fatalities caused by collisions with overhead power lines are an
important conservation issue worldwide. Although mitigation strategies can
help reduce mortalities, given their considerable cost and the vast scale
of power line infrastructure, cost-effective action requires that these
efforts be prioritised to areas with the highest potential risk to birds.
To date, this risk assessment has usually been guided by potentially
biased information on the location of recorded fatalities. Here we use six
years of GPS tracking data from endangered Tasmanian wedge-tailed eagles
to develop an alternative approach to risk assessment: fine-scale spatial
risk models based on behavioural analyses. We built and cross-validated a
model that generates spatially explicit predictions of the probability
that eagles would cross power lines at hazardous altitudes throughout the
entire Tasmanian electricity distribution network. In our model,
probability of power line crossings was most strongly associated with the
proportion of open habitat, forest edges, rural residential developments,
wet forest, and freshwater sources in the area surrounding the power
lines. Cross-validation indicated that the model effectively predicted
where Tasmanian wedge-tailed eagles cross power lines at low altitude.
Model validation suggested our approach was a powerful predictor of the
locations of power line collisions involving eagles. The locations of
almost all (94%) confirmed eagle fatalities were in the half of the total
Tasmanian power line area assigned the higher risk by the model, and 50%
of incidents occurred in the 20% of the power line area estimated to be
highest risk. Synthesis and applications. Our study illustrates a
framework for using bird movement data to provide insights into avian
behaviour and the risk they encounter around power line infrastructure.
Electricity delivery industries can use these models to identify the
electrical infrastructure that poses the highest risk to avian survival
and prioritise mitigation efforts, thereby optimizing the benefit of
investments to reduce detrimental effects on biodiversity. Our model can
inform pre-emptive mitigation across Tasmania’s 20,310 km of distribution
infrastructure to meet management targets aiming to reduce the negative
effects of power lines on the Tasmanian wedge-tailed eagle.