Scavenger removal of bird carcasses at simulated wind turbines: Does carcass type matter?

Travis L Devault,Kimberly E Linnell,Thomas W Seamans,Dale W Sparks,James C Beasley

doi:10.1002/ecs2.1994

Abstract

AbstractWind energy development can negatively impact bird populations due to bird–turbine collisions. To accurately estimate bird mortality at wind farms, the number of dead birds found under turbines is commonly corrected for carcass removal by scavengers, which is quantified by measuring persistence of experimental carcasses through time. These studies often use domestic birds as surrogates because carcasses of wild birds (e.g., raptors) are difficult to obtain. We assessed scavenger removal of carcasses from five bird species at simulated turbines to determine whether domestic surrogates are scavenged at a different rate than raptors, species of interest for wind turbine mortality. The percentage of carcasses scavenged during 14‐d rounds ranged from 34.6% for American kestrels (Falco sparverius) to 65.4% for chickens (Gallus gallus), and the percentage of carcasses completely removed ranged from 13.5% for red‐tailed hawks (Buteo jamaicensis) to 67.3% for northern bobwhites (Colinus virginianus). Carcass type (i.e., species) was the only predictor included in the best‐fit logistic regression model of complete carcass removal, and a survival analysis indicated carcass type influenced elapsed time to scavenging events. Our results suggest the use of surrogate species to quantify carcass removal at wind turbines could lead to inaccurate mortality estimates.

Highlights

Collision with wind turbines is an important source of mortality for some bird populations (Loss et al 2013, Smallwood 2013, Zimmerling et al 2013, Erickson et al 2014)
The number of carcasses investigated by vertebrates during the rounds ranged from 38 (73.1%) for northern bobwhites to 47 (90.4%) for chickens (Table 2), and the number of carcasses scavenged by vertebrates ranged from 18 (34.6%) for American kestrels to 34 (65.4%) for chickens (Table 3)
Our results clearly indicate that carcass type influenced the probability of scavenging and carcass persistence over the 14-d rounds

Summary

Introduction

Collision with wind turbines is an important source of mortality for some bird populations (Loss et al 2013, Smallwood 2013, Zimmerling et al 2013, Erickson et al 2014). In response to concerns about population-level effects of wind energy on birds and other wildlife, the U.S Fish and Wildlife Service (USFWS 2012) developed a five-tiered approach to assist wind energy companies in identifying and avoiding development at sites with a high risk to wildlife. To estimate the number of birds killed at a wind farm, trained observers search the area under turbines and record the number and species of bird (and other) carcasses found.

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Conclusion