Spatial ecology of grey squirrels (Sciurus carolinensis) in an urban environment

The North American eastern grey squirrel (Sciurus carolinensis) is a<br/>highly invasive species that has replaced the sympatric native Eurasian red<br/>squirrel (Sciurus vulgaris) across much of the United Kingdom through<br/>exploitative competition and disease spread. The city of Aberdeen remains a<br/>stronghold for the grey squirrel in Scotland, and Saving Scotland’s Red<br/>Squirrels (SSRS) has identified lack of access to perform control in private<br/>gardens as a potential barrier to eradication of the species from this urban<br/>area. Successful eradication requires (i) all individuals of a population to be<br/>vulnerable to control efforts, (ii) the rate of removal of individuals to exceed<br/>the rate of population growth, and (iii) immigration into the population to be<br/>zero. Development of effective management and control strategies for grey<br/>squirrels meeting these criteria is currently hindered by significant gaps in<br/>knowledge of urban grey squirrel spatial ecology, as highlighted by a<br/>systematic literature review, with no previous studies estimating home ranges<br/>in residential areas or quantifying space use and habitat preference at the<br/>individual level. This thesis aims to address this firstly by estimating the home<br/>ranges of 10 individual grey squirrels, tracked using GPS telemetry for up to<br/>five months in Aberdeen, and assessing habitat selection within these home<br/>ranges. This information is used to determine the distribution of traps required<br/>to put each individual of the target population at risk of coming into contact<br/>with a trap within various habitat types. Secondly, environmental factors and<br/>trapping procedures, such as pre-baiting, which are likely to influence trapping<br/>success for grey squirrels are, assessed through analysis of 12 years of<br/>historical trapping data from Aberdeen provided by SSRS. Results of this<br/>research suggest that trapping in private gardens is not necessary to the<br/>eradication of the species from Aberdeen; not one of the tracked grey<br/>squirrels’ home ranges falls entirely within residential habitat and the<br/>individuals exhibit a preference for woodland habitat. SSRS resources should<br/>be allocated to concentrating grey squirrel trapping in broadleaved and mixed<br/>woodland compartments throughout the city, with traps spaced no more than<br/>150 metres and 190 metres apart in these habitat types, respectively. Traps<br/>should be pre-baited for two weeks and trapping effort should be increased in<br/>late spring and early summer, to ensure rate of grey squirrel removal exceeds<br/>rate of population growth following the winter breeding season, and in early<br/>winter, when availability of natural food resources is low.

Name dc:type.qualificationname

Master of Research (awarded by UHI)

Level dc:type.qualificationlevel

Master's Thesis

Grantor dc:publisher.institution

University of the Highlands and Islands

Year dc:date.issued

2023

Author dc:creator

• Fitzpatrick, Devin

Advisor dc:contributor.advisor

• Smith, Melanie

Language dc:language

eng

Identifier

oai:pure.atira.dk:studenttheses/cbcc3027-75d8-46d4-afdb-81e96f67a94c

OAI identifier oai:identifier

oai:pure.atira.dk:studenttheses/cbcc3027-75d8-46d4-afdb-81e96f67a94c