Using GPS telemetry to validate least-cost modeling of gray squirrel ( Sciurus carolinensis) movement within a fragmented landscape

In Britain, the population of native red squirrels Sciurus vulgaris has suffered population declines and local extinctions. Interspecific resource competition and disease spread by the invasive gray squirrel Sciurus carolinensis are the main factors behind the decline. Gray squirrels have adapted to the British landscape so efficiently that they are widely distributed. Knowledge on how gray squirrels are using the landscape matrix and being able to predict their movements will aid management. This study is the first to use global positioning system (GPS) collars on wild gray squirrels to accurately record movements and land cover use within the landscape matrix. This data were used to validate Geographical Information System (GIS) least-cost model predictions of movements and provided much needed information on gray squirrel movement pathways and network use. Buffered least-cost paths and least-cost corridors provide predictions of the most probable movements through the landscape and are seen to perform better than the more expansive least-cost networks which include all possible movements. Applying the knowledge and methodologies gained to current gray squirrel expansion areas, such as Scotland and in Italy, will aid in the prediction of potential movement areas and therefore management of the invasive gray squirrel. The methodologies presented in this study could potentially be used in any landscape and on numerous species.

In Britain, the population of native red squirrels Sciurus vulgaris has suffered
population declines and local extinctions. Interspecific resource competition
and disease spread by the invasive gray squirrel Sciurus carolinensis are the main
factors behind the decline. Gray squirrels have adapted to the British landscape
so efficiently that they are widely distributed. Knowledge on how gray squirrels
are using the landscape matrix and being able to predict their movements will
aid management. This study is the first to use global positioning system (GPS)
collars on wild gray squirrels to accurately record movements and land cover
use within the landscape matrix. This data were used to validate Geographical
Information System (GIS) least-cost model predictions of movements and
provided much needed information on gray squirrel movement pathways and
network use. Buffered least-cost paths and least-cost corridors provide predictions
of the most probable movements through the landscape and are seen to
perform better than the more expansive least-cost networks which include all
possible movements. Applying the knowledge and methodologies gained to
current gray squirrel expansion areas, such as Scotland and in Italy, will aid in
the prediction of potential movement areas and therefore management of the
invasive gray squirrel. The methodologies presented in this study could
potentially be used in any landscape and on numerous species.

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