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.

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 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.

scholarly journals Invading parasites: spillover of an alien nematode reduces survival in a native species

2021 ◽  
Author(s):  
Claudia Romeo ◽  
Anna Pia Piscitelli ◽  
Francesca Santicchia ◽  
Adriano Martinoli ◽  
Nicola Ferrari ◽  
...  
Keyword(s):  
Body Mass ◽  
North American ◽  
Native Species ◽  
Resource Competition ◽  
Viral Disease ◽  
Red Squirrels ◽  
Local Survival ◽  
Survival And Reproduction ◽  
The Impact ◽  
Grey Squirrels

AbstractIt is widely assumed that spillover of alien parasites to native host species severely impacts naïve populations, ultimately conferring a competitive advantage to invading hosts that introduced them. Despite such host-switching events occurring in biological invasions, studies demonstrating the impact of alien macroparasites on native animal hosts are surprisingly few. In Europe, native red squirrels (Sciurus vulgaris) are replaced by introduced North American grey squirrels (S. carolinensis) mainly through resource competition, and, only in the United Kingdom and Ireland, by competition mediated by a viral disease. In Italy such disease is absent, but spillover of an introduced North American nematode (Strongyloides robustus) from grey to red squirrels is known to occur. Here, we used long-term (9 years) capture-mark-recapture and parasitological data of red squirrels in areas co-inhabited by grey squirrels in Northern Italy to investigate the impact of this alien helminth on naïve native squirrels’ body mass, local survival, and reproduction of females. We found no negative effect of the alien parasite on body mass or reproductive success, but intensity of infection by S. robustus reduced survival of both male and female squirrels. Significantly, survival of squirrels co-infected by their native nematode, Trypanoxyuris sciuri, was less affected by S. robustus, suggesting a protective effect of the native helminth against the new infection. Hence, we demonstrate that alien S. robustus spillover adds to the detrimental effects of resource competition and stress induced by grey squirrels, further reducing the fitness of the native species in the presence of the invasive competitor.

scholarly journals Disease threats posed by alien species: the role of a poxvirus in the decline of the native red squirrel in Britain

2005 ◽  
Vol 134 (3) ◽  
pp. 521-533 ◽  
Author(s):  
S. P. RUSHTON ◽  
P. W. W. LURZ ◽  
J. GURNELL ◽  
P. NETTLETON ◽  
C. BRUEMMER ◽  
...  
Keyword(s):  
Population Control ◽  
Disease Model ◽  
Red Squirrel ◽  
Grey Squirrel ◽  
Red Squirrels ◽  
Contact Rates ◽  
The United Kingdom ◽  
Model Predictions ◽  
Grey Squirrels

Red squirrels are declining in the United Kingdom. Competition from, and squirrel poxvirus (SQPV) disease carried by, grey squirrels are assumed to be determining the decline. We analyse the incidence of disease and changes in distribution of the two species in Cumbria, from 1993 to 2003 and compare these to the predictions of an individual-based (IB) spatially explicit disease model simulating the dynamics of both squirrel species and SQPV in the landscape. Grey squirrels increased whilst red squirrels declined over 10 years. The incidence of disease in red squirrels was related to the time since grey squirrels arrived in the landscape. Analysis of rates of decline in red squirrel populations in other areas showed that declines are 17–25 times higher in regions where SQPV is present in grey squirrel populations than in those where it is not. The IB model predicted spatial overlap of 3–4 years between the species that was also observed in the field. The model predictions matched the observed data best when contact rates and rates of infection between the two species were low. The model predicted that a grey squirrel population control of >60% effective kill was needed to stop the decline in red squirrel populations in Cumbria.

scholarly journals New World origins for haemoparasites infecting United Kingdom grey squirrels (Sciurus carolinensis), as revealed by phylogenetic analysis of bartonella infecting squirrel populations in England and the United States

2002 ◽  
Vol 129 (3) ◽  
pp. 647-653 ◽  
Author(s):  
K. J. BOWN ◽  
B. A. ELLIS ◽  
R. J. BIRTLES ◽  
L. A. DURDEN ◽  
J. LELLO ◽  
...  
Keyword(s):  
United States ◽  
United Kingdom ◽  
New World ◽  
Phylogenetic Analyses ◽  
The United States ◽  
Sciurus Carolinensis ◽  
Red Squirrel ◽  
Red Squirrels ◽  
The United Kingdom ◽  
Grey Squirrels

Phylogenetic analyses of bartonella have suggested divergence between bartonellae that infect mammals native to the Old and New Worlds. We characterized bartonella isolated from Eastern grey squirrels (Sciurus carolinensis) in the United States and from grey and red squirrels (Sciurus vulgaris) in the United Kingdom by nucleotide sequence comparison (gltA and groEL). Isolates from grey squirrels in the United States and the United Kingdom were identical, and most similar to Bartonella vinsonii, a species associated with New World rodents. A single and novel bartonella genotype was obtained from all 12 red squirrel isolates. Although grey squirrels were first introduced into the United Kingdom over 125 years ago, they continue to be infected solely by the bartonella associated with grey squirrels native to the United States. These results illustrate that exotic species may be accompanied by the introduction and maintenance, over many generations, of their microparasites.

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 The enemy of my enemy is my friend: native pine marten recovery reverses the decline of the red squirrel by suppressing grey squirrel populations

2018 ◽  
Vol 285 (1874) ◽  
pp. 20172603 ◽  
Author(s):  
Emma Sheehy ◽  
Chris Sutherland ◽  
Catherine O'Reilly ◽  
Xavier Lambin
Keyword(s):  
Native Species ◽  
Site Occupancy ◽  
Apparent Competition ◽  
Red Squirrel ◽  
Pine Marten ◽  
Grey Squirrel ◽  
Capture Recapture ◽  
Contrast Exposure ◽  
The Impact ◽  
Grey Squirrels

Shared enemies may instigate or modify competitive interactions between species. The dis-equilibrium caused by non-native species introductions has revealed that the outcome of such indirect interactions can often be dramatic. However, studies of enemy-mediated competition mostly consider the impact of a single enemy, despite species being embedded in complex networks of interactions. Here, we demonstrate that native red and invasive grey squirrels in Britain, two terrestrial species linked by resource and disease-mediated apparent competition, are also now linked by a second enemy-mediated relationship involving a shared native predator recovering from historical persecution, the European pine marten. Through combining spatial capture–recapture techniques to estimate pine marten density, and squirrel site-occupancy data, we find that the impact of exposure to predation is highly asymmetrical, with non-native grey squirrel occupancy strongly negatively affected by exposure to pine martens. By contrast, exposure to pine marten predation has an indirect positive effect on red squirrel populations. Pine marten predation thus reverses the well-documented outcome of resource and apparent competition between red and grey squirrels.

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