Assessment of Detection Methods and Vegetation Associations for Introduced Finlayson’s Squirrels (Callosciurus finlaysonii) in Italy

Abstract

Managing biological invasions requires rapid, cost-effective assessments of introduced species' occurrence, and a good understanding of the species' vegetation associations. This is particularly true for species that are elusive or may spread rapidly. Finlayson's squirrel (Callosciurus finlaysonii) is native to Thailand and southeastern Asia, and two introduced populations occur in peninsular Italy. One of the two introduced populations is rapidly expanding, but neither effective monitoring protocols nor reliable information on vegetation associations are available. To fill this gap, we conducted visual surveys and hair tube sampling in a periurban landscape of southern Italy to compare the effectiveness of these two methods in assessing presence of Finlayson's squirrel. We also determined the species' association with vegetation types at detection locations and nesting sites. Both visual and hair tube sampling effectively assessed the species' presence, but hair tubes resulted in fewer false absences. Moreover, when we controlled for the costs of labor and equipment, hair tubes were 33.1% less expensive than visual sampling. Presence of squirrels and their nests was positively correlated with shrub species richness, indicating that the occurrence of forests with well-developed understory may inhibit the spread of the species.

Integrating climate and land‐use change scenarios in modelling the future spread of invasive squirrels in Italy

“…Land‐use categories were grouped into broader classes (Supporting Information Table ) according to the ecology of the studied species and following the categories considered in the future land‐use change scenarios (Verburg et al, ). The four squirrel species live in forests, and show a different ability to move along tree lines, woodlots or shrubby areas (Ancillotto et al, ; Guichon & Doncaster, ; Mori et al, ; Wauters & Gurnell, ), thus forests and semi‐natural areas are considered areas suitable for dispersal and establishment. Artificial areas are semi‐permeable barriers since the four squirrel species are known to have established populations in urban areas (Ancillotto et al, ; Bertolino et al, ; Guichon & Doncaster, ; Mori et al, ).…”

“…The four squirrel species live in forests, and show a different ability to move along tree lines, woodlots or shrubby areas (Ancillotto et al, ; Guichon & Doncaster, ; Mori et al, ; Wauters & Gurnell, ), thus forests and semi‐natural areas are considered areas suitable for dispersal and establishment. Artificial areas are semi‐permeable barriers since the four squirrel species are known to have established populations in urban areas (Ancillotto et al, ; Bertolino et al, ; Guichon & Doncaster, ; Mori et al, ). Variables related to agricultural activities (e.g., permanent crops, rice fields, pastures, arable lands) were not considered because generally they represent a matrix not suitable for squirrels.…”

“…The squirrel species introduced to Europe are mainly arboreal (Ancillotto, Notomista, Mori, Bertolino, & Russo, ; Palmer et al, ), and often originate from other bioclimatic realms (Di Febbraro et al, ; Di Febbraro, Martinoli, Russo, Preatoni, & Bertolino, ). Invaded environments may be differently permeable to native and alien squirrel range expansions, according to the extent and spatial patterns of forests and other key landscape features.…”

Systematic Pathologic Findings Report of Callosciurus finlaysonii (Horsfield, 1823) (Rodentia, Sciuridae) Squirrels from Maratea Area (South Italy) to Investigate Species-Specific Pathologies, Reliability of CO2 Euthanasia Method, and Possible Use as Environmental Sentinels

“…For example, it has been demonstrated that in the Maratea area, C. finlaysonii was responsible for bark stripping damage of Carob ( Ceratonia siliqua L., 1753), Quercus virgiliana ( Quercus virgiliana Ten.) , Holm ( Quercus ilex L., 1753), and Olive ( Olea europea L., 1753) [ 7 , 8 ]. The risk of extinction is very high for native species ( Sciurus vulgaris ) in Italy, and also the International Union for Conservation of Nature (IUCN) enrolled this species among those of the red list since 2013.…”

A cross-sectional survey to evaluate the pet squirrel population and ownership profiles

“…Finlayson's squirrel is an arboreal rodent native to Thailand, Myanmar, Laos, Cambodia and Vietnam (Ancillotto et al, 2018). A few populations of this squirrel, introduced through the pet trade (Bertolino and Lurz, 2013), have established outside its native range in the last 35-40 years.…”