Do supplemental perches influence electrocution risk for diurnal raptors?

Background:Power lines are amongst the main causes of mortality for birds globally.Electrocution drives the population dynamics of several threatened species of raptors,at local and global scales.Among the many solutions that have been tested to minimize this threat are supplemental perches;however,their efficiency has rarely been assessed.Methods:We designed 43 transects in 4 districts in mainland Portugal to gather data from birds perching on pylons with or without supplemental perches.From 2015 to 2018,transects were surveyed by car at least once.We analyzed the factors driving the use of these supplemental perches,and we analyzed if there were differences in the perceived risk(calculated from measurements and not from field surveys)depending on whether the perching was on pylons with or without supplemental perches.Results:We recorded 548 perches of 14 species.Weather conditions seemed to play a role in birds’choice of pylons with supplemental perches versus pylons without supplemental perches.Models also indicated a strong influence of observational conditions.The use of models showed us an important specific effect in the selection of supplemental perches where available:there are some species with a greater tendency to perch on supplemental perches,even when they use both pylons with and without supplemental perches.For most of the analyzed species and species groups,perceived risk was higher in pylons without supplemental perches compared to pylons with supplemental perches,but there were differences between species.Conclusions:Supplemental perches may be a useful and efficient tool for mitigating raptor electrocution.However,there are many influential factors affecting their success,and their effectiveness with different species groups is not homogeneous.Some studies show higher electrocution rates for certain species and devices and thus,their efficacy must be validated.We propose a two-step validation process,first in controlled conditions and then in the field.A common protocol should be established to enable comparisons between studies.

Deaths Due to Electrocution:An Evaluation of Death Scene Investigations and Autopsy Findings

The purpose of the study was to delineate the epidemiological characteristics of electrocution deaths in Maryland,identify any potential risks,and address preventive measures.A retrospective review of all the deaths due to electrocution was conducted at the Office of the Chief Medical Examiner in the State of Maryland from 2005 to 2015.During the 11-year period,a total of 55 electrocution deaths were identified from the autopsy cases at the statewide medical examiner system.More males died of electrocution than females with its ratio of(M:F)=9:l.Of the 55 cases,67.3%were White,18.2%were African-American,12.7%were Hispanic,and 1.8%were other races.The age of the victims ranged from 4 to 83 years with mean age of 40 years.>96%deaths due to accidents and 3.4%were suicide.The majority of deaths(70.9%)were caused by high-voltage circuits.Approximately 64%of fatalities were work-related accidents.The study indicated that electrocution deaths frequently affected young male workers who were in contact with a high-voltage currents while on the job.The detailed death scene investiRation and autopsy findings are presented.The potential hazards of electricity must continue to be addressed in public safety campaigns to prevent such deaths.Strategies should ensure safe work environments for any contact with electric currents.

Avian-power line interactions in the Gobi Desert of Mongolia:are mitigation actions effective?

Background:Electrocution and collisions on power lines are among the leading causes of non-natural mortality for birds.Power lines are exponentially increasing,particularly in developing countries,but mitigation strategies to prevent bird mortality are questionable.Mongolia combines a recently increased power line network,an abundant raptor population,a dangerous crossarm configuration and a habitat with no natural perches,producing many bird-power line interactions.Our aim is to assess the bird mortality caused by power lines in the Gobi Desert of Mongolia,to determine the factors increasing the risk of bird electrocution,and to evaluate the effectiveness of used retrofitting measures.Methods:In July 2019 we covered 132.9 km of 15 kV power lines checking 1092 poles.We also conducted bird tran-sects to record raptor and corvid richness and abundance,to assess species vulnerability to electrocution.Results:We recorded 76 electrocuted birds of 7 species.Electrocution rate was 6.96 birds/100 poles.The most affected species were Common Raven(Corvus corax)and Upland Buzzard(Buteo hemilasius),highlighting the electro-cution of 5 endangered Saker Falcons(Falco cherrug).By contrast,we only recorded 8 individuals of 5 species collid-ing with wires,the most affected being Pallas’s Sandgrouse(Syrrhaptes paradoxus).About 76.1%of sampled poles had some mitigation measure.Of these,96.6%were brush perch deflectors and 3.4%rotating-mirrors perch deter-rents.We found differences in electrocution rates among crossarm configurations,with the strain insulator with one jumper being the most lethal.Additionally,we found no correlation between bird abundance and electrocution rates,suggesting that some species are more sensitive to electrocution.Although no differences in total bird electrocu-tion rates were detected between poles with and without perch deterrents,when bird size is considered,deterrents reduced the mortality rate of small birds,while they were ineffective for medium-sized birds.Conclusions:Despite the widespread use of perch deterrents in the Mongolian power line network,there is still an alarming electrocution rate.This strategy is ineffective and some mechanisms,such as brush perch deflectors,may increase the electrocution rate for some medium-sized birds.Finally,we propose strategies to minimize the avian electrocution rate in the Gobi Desert.