Spatial ecology of an urban eastern grey kangaroo (Macropus giganteus) population: local decline driven by kangaroo–vehicle collisions

Abstract

Context As urban landscapes proliferate globally, the need for research into urban wildlife interactions is magnified. The eastern grey kangaroo (Macropus giganteus) is a widespread species commonly involved in wildlife–vehicle collisions in urban areas in Australia. Despite the many urban kangaroo populations and associated conflicts with human activities, few studies have examined how eastern grey kangaroos interact with, and are affected by, the urban matrix. Aims The present study aimed to quantify kangaroo demography, movements, habitat utilisation and exposure to risks during a period of intensive urban development in a rapidly changing suburb located in a region undergoing high urban growth rates. Methods We utilised foot-based census surveys, global positioning system (GPS) collars, direct observations and reports of wildlife mortality between 2014 and 2016. Geographical information systems (GIS) were used to integrate GPS-tracking data with spatial layers, to quantify kangaroo movements and habitat utilisation. Key results The kangaroo population underwent a steep decline and kangaroo–vehicle collisions were the main source of mortality (73%) during the study period. Kangaroos were regularly exposed to the risk of injury, with roads intersecting many parts of their home range. Kangaroos showed positive habitat selection both for lawn and forest habitats and kangaroo movement and presence at the study site were influenced by high-quality forage and cover. Conclusions The present research has highlighted that despite areas of suitable habitat remaining, road-kill was a major contributor to localised kangaroo-population decline. We showed that habitat preferences of eastern grey kangaroos in this urban area were consistent with those in natural landscapes. Implications The present study is the first to implicate kangaroo–vehicle collisions as the major factor in population decline in kangaroos. These findings can be utilised to guide design and placement of kangaroo–vehicle collision mitigation and assist in planning of urban areas, particularly where kangaroo populations are in decline. Local extirpation of urban kangaroo populations would be greatly reduced by incorporating site-specific kangaroo habitat preferences and existing patterns of kangaroo habitat use in infrastructure planning. The study has contributed to our understanding of the effects of roads on urban wildlife in general and highlighted the importance of landscape permeability.

Fright or Flight? Behavioural Responses of Kangaroos to Drone-Based Monitoring

“…The first site (Sippy Downs) (26 • 43 01 S, 153 • 03 56 E) was an urban site located on a university campus where kangaroos persist in the urban matrix amongst built infrastructure, preferentially utilising grass and forest areas on the campus. Pressures from ongoing infrastructure development, human population growth and urban encroachment on kangaroo habitats have caused a steep decline in this kangaroo population from approximately 80 kangaroos in 2010 [25] to 15 resident kangaroos remaining on site at the time of this study (average mob size was 3.4). The second site (Lake Weyba) (26 • 26 16 S, 153 • 03 44 E) was a peri-urban private property dominated by coastal heath, with small patches of mowed lawns throughout.…”

Not all urban landscapes are the same: interactions between urban land use and stress in a large herbivorous mammal

“…Indeed, a meta-analysis of physiological responses of birds and mammals to habitat disturbance revealed consistent changes in stress hormones in response to habitat degradation (Messina et al 2018). An urban eastern grey kangaroo's home range is estimated at between 20 and 100 ha (Brunton et al 2018b, Henderson et al 2018, similar to that for kangaroos in most non-urban settings (Jaremovic and Croft 1987, 1991, Moore et al 2002. While it was not possible to measure the amount of continuous habitat for all study sites, at southern urban sites the average continuous habitat was approximately 140 ha, much larger than the average 40 ha of the northern urban sites.…”

“…For example, urban areas may be benign or even of benefit to some mammal species due to the increased availability of some resources in the urban environment (Dowle et al 2013, Rakotoniaina et al 2016, Lyons et al 2017) and this may partly explain the lower FGM levels measured in urban southern kangaroo populations compared to non-urban. Kangaroos are known to prefer heterogeneous habitats and select habitat areas with high quality forage with shelter nearby (Moore et al 2002, Brunton et al 2018b. Urban landscapes in the southern study region may offer more consistent resources of this type in the form of managed golf courses, parklands and reserves in comparison to the variable availability of quality forage and water available in the non-urban sites in our study, where four sites were in the sub-alpine Namadgi National Park.…”

“…An urban eastern grey kangaroo's home range is estimated at between 20 and 100 ha (Brunton et al. , Henderson et al. ), similar to that for kangaroos in most non‐urban settings (Jaremovic and Croft , , Moore et al.…”

“…, Brunton et al. ). Urban landscapes in the southern study region may offer more consistent resources of this type in the form of managed golf courses, parklands and reserves in comparison to the variable availability of quality forage and water available in the non‐urban sites in our study, where four sites were in the sub‐alpine Namadgi National Park.…”