What influences road mortality rates of eastern grey kangaroos in a semi-rural area?

Jai M Green-Barber,Julie M Old

doi:10.1186/s40850-019-0047-8

Abstract

BackgroundRoads have major ecological impacts on wildlife. Vehicle collisions most frequently impact large herbivores due to their larger home range compared to smaller animals, and higher population density compared to carnivores. Kangaroos (Macropus spp.) account for a large proportion of reported wildlife vehicle collisions that occur in N S W, Australia. We aimed to evaluate what influenced road mortality of eastern grey kangaroos (Macropus giganteus) in a temperate rural/suburban region. The location of roadkilled kangaroos found on or near two 1 km stretches of road in Richmond NSW was recorded throughout 2014 and 2015. Weather and moon phase data were recorded for the date of each roadkilled kangaroo. Transects were setup on both roads, and multiple road and landscape features, including the width of roadside, fence construction, habitat type, and distance from street lights measured at 50 m intervals. Data were analyzed to explore which landscape features and temporal factors influenced the occurrence of a roadkill hotspot.ResultsMore kangaroo road mortalities occurred during periods of low temperature and low rainfall, and these factors are likely to affect forage quality. Fewer mortalities occurred when rain was falling. A greater number of mortalities occurred during the waning gibbous phase of the lunar cycle. Significantly more road mortalities occurred a short distance from the end of a section of street lights.ConclusionsThe findings suggest that illumination influences the likelihood of kangaroo road mortalities. Large herbivores are particularly sensitive to habitat fragmentation because they need unrestricted access to large continuous habitat. Knowledge of factors that influence where and when kangaroos are most likely to cross roads can be used to inform more targeted management strategies and improve future road design and habitat connectivity to reduce the incidence of wildlife vehicle collisions.

Highlights

Roads have major ecological impacts on wildlife
Australia’s road network covers over 810,600 km [15], and large terrestrial mammals such as eastern grey kangaroos account for a large proportion of wildlife vehicle collisions
Klöcker et al [16] recorded the number of eastern grey kangaroos (Macropus giganteus), western grey kangaroos (Macropus fuliginosus), red kangaroos (Macropus rufus), common wallaroos (Macropus robustus) killed on a section of outback highway in far western NSW, and reported a roadkill rate of 0.03 kangaroos per km, per day, whilst Burgin and Brainwood [15] estimated that over 9 million kangaroos and wallabies are killed annually on Australian roads

Summary

Introduction

Roads have major ecological impacts on wildlife. Vehicle collisions most frequently impact large herbivores due to their larger home range compared to smaller animals, and higher population density compared to carnivores. Kangaroos (Macropus spp.) account for a large proportion of reported wildlife vehicle collisions that occur in N S W, Australia. Roads have multiple ecological impacts on wildlife including fragmentation of habitats and isolation of populations [1, 2]. Australia’s road network covers over 810,600 km [15], and large terrestrial mammals such as eastern grey kangaroos account for a large proportion of wildlife vehicle collisions. Klöcker et al [16] recorded the number of eastern grey kangaroos (Macropus giganteus), western grey kangaroos (Macropus fuliginosus), red kangaroos (Macropus rufus), common wallaroos (Macropus robustus) killed on a section of outback highway in far western NSW, and reported a roadkill rate of 0.03 kangaroos per km, per day, whilst Burgin and Brainwood [15] estimated that over 9 million kangaroos and wallabies are killed annually on Australian roads. Kangaroo vehicle collisions lead to high costs for drivers and insurance companies, in the tens of millions of dollars, through vehicle damage and human distress, injury and death [16, 17]

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