DOI: 10.5061/dryad.rbnzs7h9n
title: Data and code from: A large-scale experiment demonstrates line marking reduces power line collision mortality for large terrestrial birds, but not bustards, in the Karoo, South Africa

description: Line markers are widely used to mitigate bird collisions with power lines,
 but few studies have robustly tested their efficacy. Power line collisions
 are an escalating problem for several threatened bird species endemic to
 southern Africa, so it is critical to know whether or not marking works to
 adequately manage this problem. Over 8 years, a large-scale experiment was
 set up on 72 of 117 km of monitored transmission power lines in the
 eastern Karoo, South Africa, to assess whether line markers reduce bird
 collision mortality, particularly for Blue Cranes Grus paradisea and
 Ludwig’s Bustards Neotis ludwigii. We tested the two marking devices
 commonly used in South Africa: bird flappers and static bird flight
 diverters. Using a before-after-control-impact design, we show that line
 marking reduced collision rates for Blue Cranes by 92% (95% CI 77-97%) and
 all large birds by 51% (95% CI 23-68%), but had no effect on bustards.
 Both marker types appeared similarly effective. Given that monitoring at
 this site also confirmed high levels of mortality of a range of species of
 conservation concern, we recommend that marking be widely installed on new
 power lines. However, other options need to be explored urgently to reduce
 collision mortality of bustards. Five bustard species were in the top ten
 list of most frequently found carcasses, and high collision rates of
 Ludwig’s Bustards (0.68 birds·km-1·year-1 uncorrected for survey biases)
 add to wider concerns about population level effects for this
 range-restricted and Endangered species.   This dataset includes
 the data and R code for this journal paper.
description: This dataset was collected through surveys of high voltage power
 lines near De Aar in the Karoo, South Africa 2008-2016 to identify dead
 birds that had collided with the power lines. Part of the line was marked
 with flappers and bird flight diverters in 2011 to allow testing of
 whether these marking devices reduced the collision rate for the most
 common species. There are 2 csv files containing
 data: 1. BootstrapOct2020 - this data was used to
 generate collision rates through bootstrapping in the pre-marking period.
 It is the number of collisions per span check by top 10 most commonly
 recovered species. The file gives line ID, powerline (DH2, HP1 or HP2),
 year (1 or 2), season (winter, spring, summer or autumn), survey (date),
 span number and then number of dead birds found of LB (Ludwig's
 Bustard), BC (Blue Crane), NBK (Northern Black Korhaan), WS (White Stork),
 Sec (Secretarybird), KK (Karoo Korhaan), PC (Pied Crow), BK (Blue
 Korhaan), SWG (Spur-winged Goose) and KB (Kori Bustard).
 2. MarkingOct2020 - this data was used to assess marker efficacy.
 It is the number of collisions per section check in the reduced experiment
 for 4 bird groups, with the number of spans in each section check. The
 file gives line ID, date, season (winter, spring, summer or autumn),
 experiment (i.e. before or after the markers were installed), powerline
 (DH2, HP1 or HP2), block (2-8), span number, treatment (as either control
 (acontrol), flapper or bfd (bird flight diverter)), TreatSimple (as either
 control (acontrol) or marked), LB (number of dead Ludwig's Bustards
 found), BC (number of dead Blue Cranes found), BustardsOther (number of
 dead bustards excluding LBs found), LargeOther (number of large dead birds
 other than bustards or BCs found), TotalLarge (number of all dead large
 birds found - i.e. sum of LB, BC, BustardsOther and LargeOther) and
 count_of_spans (number of spans in the treatment section).
 There is one R file 'CONDOR-20-044 - R code De Aar marking
 experiment - Oct 20' which gives the code to run all the analyses for
 bootstrapped collision rates and efficacy of line marking.
 There is one ReadMe file containing all necessary
 information.
description: ReadMe file uploaded.