Spacing behaviour, kinship, and population dynamics of grey squirrels in a newly colonized broadleaf woodland in Italy

2001 ◽  
Vol 79 (9) ◽  
pp. 1533-1543 ◽  
Author(s):  
John Gurnell ◽  
Luc A Wauters ◽  
Damiano Preatoni ◽  
Guido Tosi
Keyword(s):  
Home Range ◽  
Home Range Size ◽  
Core Area ◽  
Adult Survival ◽  
Sciurus Carolinensis ◽  
Red Squirrel ◽  
Grey Squirrel ◽  
Colonization Process ◽  
Juvenile Males ◽  
Grey Squirrels

Eastern grey squirrels, Sciurus carolinensis, introduced to Britain and northern Italy are replacing the native Eurasian red squirrel, Sciurus vulgaris. We studied the pattern of colonization of a high-quality broadleaf woodland by grey squirrels by means of livetrapping and radio-tracking. The studies started in July 1996, when six grey squirrels (four males, two females) first colonized the woodland, and lasted until November 1998, when densities exceeded those of the local red squirrel population. Grey squirrel colonization was rapid, with a high proportion of adult and yearling females breeding. Juvenile recruitment was also higher than in stable populations in Britain. Adult survival was better in 1997 (83%) than in 1998 (47%), with predation accounting for 67% of losses in 1998. This indicates the effects of local predator communities on the colonization process. Densities of grey squirrels were moderate in 1998, with a maximum of 1.9 squirrels/ha and we expect density to increase further. Adult home range sizes were three to four times larger than those of subadults, and male ranges were larger than those of females. Body mass was positively correlated with both total home range size and core-area size. Core-area size for adults was inversely correlated with food availability. Juvenile female grey squirrels were philopatric, forming female kin groups, while most juvenile males settled outside the mother's home range.

scholarly journals Natural strongholds for red squirrel conservation in Scotland

2021 ◽  
Vol 43 ◽  
pp. 93-108
Author(s):  
Andrew Slade ◽  
Andy White ◽  
Kenny Kortland ◽  
Peter W. W. Lurz
Keyword(s):  
Management Practice ◽  
Management Policy ◽  
Sciurus Carolinensis ◽  
Red Squirrel ◽  
Grey Squirrel ◽  
Case Scenario ◽  
Red Squirrels ◽  
Worst Case ◽  
Standard Management ◽  
Grey Squirrels

The Eurasian Red Squirrel (Sciurus vulgaris) is under threat from the invasive North American eastern Grey Squirrel (Sciurus carolinensis) with 80% of the remaining red squirrel populations in the British Isles found in Scotland. In this study we develop a spatially explicit mathematical model of the red and grey squirrel system and use it to assess the population viability of red squirrels across Scotland. In particular, we aim to identify existing forests – natural strongholds for red squirrels – that can successfully support red squirrels under UK Forestry Standard management and protect them from potential disease-mediated competition from grey squirrels. Our model results indicate that if current levels of grey squirrel control, which restrict or reduce the distribution of grey squirrels, are continued then there will be large expanses of forests in northern Scotland that support viable red squirrel populations. Model results that represent (hypothetical) scenarios where grey squirrel control no longer occurred indicated that grey squirrel range expansion and the process of red squirrel replacement would be slow. Model results for an assumed worst-case scenario where grey squirrels have expanded to all regions in Scotland identified forest regions – denoted natural strongholds – that could currently support red squirrels under UK Forestry Standard management practice. The results will be used to inform forest management policy and support a strategic review of red squirrel management by land management agencies and other stakeholders.

scholarly journals An Opportunistic Assessment of the Impact of Squirrelpox Disease Outbreaks upon a Red Squirrel Population Sympatric with Grey Squirrels in Wales

Animals ◽  
2022 ◽  
Vol 12 (1) ◽  
pp. 99
Author(s):  
Craig M. Shuttleworth ◽  
David Everest ◽  
Paul Holmes ◽  
Suzi Bell ◽  
Rachel Cripps
Keyword(s):  
Survival Rates ◽  
Disease Outbreaks ◽  
Sciurus Carolinensis ◽  
Red Squirrel ◽  
Grey Squirrel ◽  
Red Squirrels ◽  
Local Survival ◽  
Temporal And Spatial ◽  
The Impact ◽  
Grey Squirrels

Native red squirrels (Sciurus vulgaris) persisted in the coastal mainland woodlands of northern Gwynedd whilst sympatric with an invasive grey squirrel (Sciurus carolinensis) population suppressed by culling. Squirrelpox disease in the red squirrel population was recorded in 2017 and 2020/21. An autumn 2020 outbreak was associated with only 17.4% of animals caught and marked in the preceding June known to be present in March 2021. Despite an opportunistic data collection lacking the rigour of empirical experimental design, we observed low local survival rates similar to previously published accounts reported during major squirrelpox outbreaks. The use of a conservation dog to detect red squirrel carcasses resulted in positive detection and confirmation of a temporal and spatial expansion of one disease outbreak. The study is the first in Wales to use conservation dogs and the findings reinforce the vital strategic importance of geographical isolation reducing sympatry of red with grey squirrels in European regions where the introduced congener is a source of the squirrelpox infection.

Influence of field technique, density, and sex on home range and overlap of the southern red-backed vole (Myodes gapperi)

2019 ◽  
Vol 97 (12) ◽  
pp. 1101-1108
Author(s):  
Honora B. Tisell ◽  
Allyson L. Degrassi ◽  
Ryan B. Stephens ◽  
Rebecca J. Rowe
Keyword(s):  
Home Range ◽  
Field Method ◽  
Home Range Size ◽  
Range Size ◽  
Eastern Hemlock ◽  
Core Area ◽  
Population Fluctuations ◽  
Mark Recapture ◽  
Shared Space ◽  
Data Density

Home range is shaped by an individual’s interactions with the environment and conspecifics, and both size and placement may vary in response to population fluctuations. The method used to collect locational data may also affect home-range estimates. We examined the effect of density, sex, and field method on home range of southern red-backed voles (Myodes gapperi (Vigors, 1830)) inhabiting eastern hemlock (Tsuga canadensis (L.) Carrière) forests. Twelve mark–recapture grids were used to census M. gapperi from 2014 to 2017. In 2017, individuals were radio-collared. Home-range size, core-area size, and shared space were calculated using kernel density estimators from both mark–recapture and radiotelemetry data. Density effects on home range and core area were analyzed and differences between sex and field method were compared. We found (i) density did not affect home-range size, (ii) male home range was larger than female home range, (iii) females shared space more frequently and to a greater extent with males than other females, and (iv) home-range estimates were not significantly different between mark–recapture and radiotelemetry. Male home range, however, was larger under radiotelemetry and may reflect a truncation effect when mark–recapture grid size is smaller than male home range.

Distribution and status of the Red Squirrel (Sciurus vulgaris) and Grey Squirrel (Sciurus carolinensis) in Ireland

Mammal Review ◽  
2000 ◽  
Vol 30 (1) ◽  
pp. 45-56 ◽  
Author(s):  
D. O. Teangana ◽  
S. Reilly ◽  
W. I. Montgomery ◽  
J. Rochford
Keyword(s):  
Sciurus Carolinensis ◽  
Red Squirrel ◽  
Sciurus Vulgaris ◽  
Grey Squirrel

scholarly journals Factors Associated With Variation in Home-Range Size of Appalachian Ruffed Grouse (Bonasa Umbellus)

The Auk ◽  
2007 ◽  
Vol 124 (4) ◽  
pp. 1407-1424 ◽  
Author(s):  
Darroch M. Whitaker ◽  
Dean F. Stauffer ◽  
Gary W. Norman ◽  
Patrick K. Devers ◽  
John Edwards ◽  
...  
Keyword(s):  
Home Range ◽  
Home Range Size ◽  
Range Size ◽  
Home Ranges ◽  
Ruffed Grouse ◽  
Bonasa Umbellus ◽  
High Quality ◽  
Game Birds ◽  
Study Sites ◽  
Juvenile Males

Abstract From 1996 to 2001, researchers at 10 Appalachian study sites collected radiotracking data sufficient to delineate 1,054 seasonal home ranges of Ruffed Grouse (Bonasa umbellus; hereafter “grouse”). Using information-theoretic model selection and paired comparison of home ranges from individual grouse, we evaluated individual, local, and landscape factors hypothesized to affect grouse home-range size. Females and juvenile males occupied home ranges that averaged >2× larger than those of adult males, and home ranges of females averaged 2.6× larger during successful breeding seasons than during years of reproductive failure. Clearcuts and forest roads are considered high-quality covers, and both were more prevalent in smaller home ranges. Several factors operating at a regional and landscape scale were also important. Previous studies have reported that southern grouse use relatively large home ranges, and we observed a continuous decline in home-range size with increasing latitude across the 710-km range spanned by our study sites. Home-range size of males, particularly juvenile males, was positively related to an index of population density. Given the species' “dispersed lekking” mating system, we interpret this as evidence of competition for preferred display sites. As has been reported for other game birds, all sex and age classes of grouse used smaller home ranges following closure of sites to hunting. Grouse inhabiting oak-hickory forests used larger home ranges than conspecifics in mixed mesophytic forests, and other factors interacted with forest type. In oak-hickory forests, female home-range size was inversely related to use of mesic bottomlands, which support important forage plants, and home ranges of adult grouse increased 2.5× following poor hard-mast crops. By contrast, home ranges of grouse inhabiting mixed mesophytic forests were unrelated to use of bottomlands, and the influence of hard mast was reduced. This is in line with the view that in Appalachian oak-hickory forests, grouse are under strong nutritional constraint. However, this constraint is reduced in mixed mesophytic forests, likely because of the presence of high-quality alternative foods (e.g., cherry [Prunus spp.] and birch [Betula spp.]). Facteurs associés à une variation de la taille du domaine vital de Bonasa umbellus dans les Appalaches

scholarly journals Native and invasive squirrels show different behavioural responses to scent of a shared native predator

2020 ◽  
Vol 7 (2) ◽  
pp. 191841 ◽  
Author(s):  
Joshua P. Twining ◽  
W. Ian Montgomery ◽  
Lily Price ◽  
Hansjoerg P. Kunc ◽  
David G. Tosh
Keyword(s):  
Species Interactions ◽  
Native Species ◽  
Prey Species ◽  
Red Squirrel ◽  
Pine Marten ◽  
Grey Squirrel ◽  
Red Squirrels ◽  
Behavioural Responses ◽  
Grey Squirrels ◽  
Native Predator

Invasive species pose a serious threat to native species. In Europe, invasive grey squirrels ( Sciurus carolinensis ) have replaced native red squirrels ( Sciurus vulgaris ) in locations across Britain, Ireland and Italy. The European pine marten ( Martes martes ) can reverse the replacement of red squirrels by grey squirrels, but the underlying mechanism of how pine martens suppress grey squirrels is little understood. Research suggests the reversal process is driven by direct predation, but why the native red squirrel may be less susceptible than the invasive grey squirrel to predation by a commonly shared native predator, is unknown. A behavioural difference may exist with the native sciurid being more effective at avoiding predation by the pine marten with which they have a shared evolutionary history. In mammals, olfactory cues are used by prey species to avoid predators. To test whether anti-predator responses differ between the native red squirrel and the invasive grey squirrel, we exposed both species to scent cues of a shared native predator and quantified the responses of the two squirrel species. Red squirrels responded to pine marten scent by avoiding the feeder, increasing their vigilance and decreasing their feeding activity. By contrast, grey squirrels did not show any anti-predator behaviours in response to the scent of pine marten. Thus, differences in behavioural responses to a shared native predator may assist in explaining differing outcomes of species interactions between native and invasive prey species depending on the presence, abundance and exposure to native predators.

Social Structure and Patterns of Movement of the Western Pebble-mound Mouse, Pseudomys chapmani, at Marandoo, Western Australia

1997 ◽  
Vol 24 (3) ◽  
pp. 295 ◽  
Author(s):  
S. D. Anstee ◽  
J. D. Roberts ◽  
J. E. O'Shea
Keyword(s):  
Home Range ◽  
Home Range Size ◽  
Ore Deposits ◽  
Core Area ◽  
Home Ranges ◽  
Economic Significance ◽  
Iron Ore Deposits ◽  
The Individual ◽  
High Level ◽  
The Impact

Mounds of the western pebble-mound mouse, Pseudomys chapmani, are found throughout the species’ Pilbara range in areas with iron-ore deposits of economic significance. Translocation techniques are being examined as a means of minimising the impact of mining on this species. In the absence of detailed information on the biology of Pseudomys chapmani, translocation is inadvisable. To provide such basic information, animal densities, mound demographics and population sizes, and home-range and core-area sizes were obtained by a combination of trapping and radio-tracking. Mounds of Pseudomys chapmani were found to be inhabited by social groups of up to 12 animals. Estimates of home-range size gave mean ( s.e.) values of 14·4 6·7 ha and 4·6 2·7 ha for males and females, respectively; core areas were recorded at 0·93 0·29 ha for males and 0·29 0·16 ha for females. Considerable overlap of home ranges was recorded between individuals from the same and different mounds. Overlap at the core-area level occurred only between individuals from the same mound. The high level of social complexity and mound fidelity indicates that translocations should be directed at the level of the social group rather than at the level of the individual.

Home-range size of northern flickers (Colaptes auratus) in relation to habitat and parental attributes

2003 ◽  
Vol 81 (6) ◽  
pp. 954-961 ◽  
Author(s):  
C L Elchuk ◽  
K L Wiebe
Keyword(s):  
Home Range ◽  
Vegetation Type ◽  
Ground Cover ◽  
Spatial Arrangement ◽  
Home Range Size ◽  
Range Size ◽  
Core Area ◽  
Nest Density ◽  
Home Ranges ◽  
Colaptes Auratus

Energetic requirements during the breeding season and environmental factors such as food abundance and habitat quality may influence spatial use of the landscape by adult birds. We determined home-range and core-area sizes for 52 adult northern flickers (Colaptes auratus) during the brood-rearing period in 1999 and 2000 in British Columbia. We examined the relationship between home-range size and correlates of energetic demands (age, sex, body size, brood size, nest density, laying attempt). We also examined the association between vegetation type at the landscape scale and ground-cover characteristics at the foraging scale with home-range size, core-area size, and maximum distance flown from the nest to forage. Mean home-range size was 25 ha, with a mean core area of 7 ha. Home-range size was positively related to laying attempt and nearest neighbour distance. No significant relationships were found at the landscape level between vegetation type and home-range size or between ground-cover characteristics and core-area size. However, flickers flew farther to forage in home ranges with tall vegetation and bare ground. Home-range size of flickers may be related to both energetic demands on the adults and on the spatial arrangement of quality foraging patches around the nest site.

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