Modelling red squirrel population viability under a range of landscape scenarios in a fragmented woodland ecosystem on the Solway Plain, Cumbria, UK.

To assess the viability of the red squirrel Sciurus vulgaris in fragmented woodlands on the Solway Plain we used a combination of Vortex population viability analysis and BEETLE (Biological and Environmental Evaluation Tools for Landscape Ecology). Habitat fragmentation and the expansion of the North American grey squirrel S. carolinensis have had a detrimental effect upon red squirrel populations in the UK; assessing the viability of the remaining populations can guide in conservation management decisions. The initial field work showed red squirrels to use 5 of the 23 woodland fragments on the Solway Plain at a density of 0.65 squirrels ha-1, with a minimum dynamic area of 91 ha of red squirrel woodland habitat being identified using Vortex. Red squirrels may use more than one woodland fragment in its home range as long as fragments are connected functionally with the land cover between fragments producing a low cost for the squirrel. The functional connectivity of these woodland fragments was modeled within BEETLE to create habitat networks. Vortex was then used to identify which habitat networks would hold a viable population. Two areas were identified which could, if the correct landscape management is prescribed, potentially hold viable populations of red squirrels on the Solway Plain. This combination of behavioral, demographic and landscape modeling allows scenario building and has application across a wide range of conservation area design problems

The spatial spread of the grey squirrel in Britain

Around the turn of the century the North American grey squirrel, Sciurus carolinensis, was releasted from various sites in Britain. Since then the grey squirrel has successfully spread to colonize much of England, Wales and the Scottish Lowlands. Simultaneously, the indigenous red squirrel, Sciurus vulgaris, has disappeared from these localities. Three hypotheses have been put forwarded to account for this phenomenon: (i) competition between the reds and the greys, (ii) environmental changes that reduced the red squirrel population independent of the grey squirrel population, and (iii) introduction of diseases by the greys

Hazards to golden-mantled ground squirrels and associated secondary hazard potential from strychnine baiting for forest pocket gophers

Radio telemetry and capture-recapture techniques were used to evaluate the hazards to golden-mantled ground squirrels (Spermophilus lateralis) from hand baiting with 0.5% strychnine-treated oats for western pocket gophers (Thomomys mazama) on conifer plantations in eastern Oregon. Toxicology data were collected on field-killed and caged ground squirrels and on caged mink (Mustela vison), great horned owls (Bubo virginianus), and red-tailed hawks (Buteo jamaicensis). Ground squirrel populations were reduced 50 to 75% following underground baiting for pocket gophers. Maximum amount of strychnine alkaloid found in cheek pouches and carcass of a field-killed golden-mantled ground squirrel was 2.88 mg. Mean amount of strychnine in carcasses was 0.35 mg; almost all occurred in the gut. The estimated LD50 for mink was 0.6 mg/kg. The lowest lethal dose for great horned owls and red-tailed hawks was 7.7 mg/kg and 10.2 mg/kg, respectively. The LD50 for owls and hawks was not determined. Long-term effects on golden-mantled ground squirrel populations and secondary hazard potential to owls and hawks were judged to be minimal. Wild mustelids as large as mink could be adversely affected by consuming the gut content of strychnine-killed golden-mantled ground squirrels

Squirrelpox virus: assessing prevalence, transmission and environmental degradation

Red squirrels (Sciurus vulgaris) declined in Great Britain and Ireland during the last century, due to habitat loss and the introduction of grey squirrels (Sciurus carolinensis), which competitively exclude the red squirrel and act as a reservoir for squirrelpox virus (SQPV). The disease is generally fatal to red squirrels and their ecological replacement by grey squirrels is up to 25 times faster where the virus is present. We aimed to determine: (1) the seropositivity and prevalence of SQPV DNA in the invasive and native species at a regional scale; (2) possible SQPV transmission routes; and, (3) virus degradation rates under differing environmental conditions. Grey (n = 208) and red (n = 40) squirrel blood and tissues were sampled. Enzyme-linked immunosorbent assay (ELISA) and quantitative real-time polymerase chain reaction (qPCR) techniques established seropositivity and viral DNA presence, respectively. Overall 8% of squirrels sampled (both species combined) had evidence of SQPV DNA in their tissues and 22% were in possession of antibodies. SQPV prevalence in sampled red squirrels was 2.5%. Viral loads were typically low in grey squirrels by comparison to red squirrels. There was a trend for a greater number of positive samples in spring and summer than in winter. Possible transmission routes were identified through the presence of viral DNA in faeces (red squirrels only), urine and ectoparasites (both species). Virus degradation analyses suggested that, after 30 days of exposure to six combinations of environments, there were more intact virus particles in scabs kept in warm (25°C) and dry conditions than in cooler (5 and 15°C) or wet conditions. We conclude that SQPV is present at low prevalence in invasive grey squirrel populations with a lower prevalence in native red squirrels. Virus transmission could occur through urine especially during warm dry summer conditions but, more notably, via ectoparasites, which are shared by both species

Red-Cockaded Woodpecker Nesting Success, Forest Structure, and Southern Flying Squirrels in Texas

For several decades general opinion has suggested that southern flying squirrels (Gluucomys volans) have a negative effect on Red-cockaded Woodpeckers (Picoides borealis) through competition for cavities and egg/nestling predation. Complete removal of hardwood trees from Red-cockaded Woodpecker cavity tree clusters has occurred on some forests because southern flying squirrel abundance was presumed to be associated with the presence and abundance of hardwood vegetation. In some locations, southern flying squirrels have been captured and either moved or killed in the name of Red-cockaded Woodpecker management. We determined southern flying squirrel occupancy of Red-cockaded Woodpecker cavities in loblolly (Pinus taeda)-shortleaf (P. echinata) pine habitat (with and without hardwood midstory vegetation) and longleaf pine (P. pulustris) habitat (nearly devoid of hardwood vegetation) during spring, late summer, and winter during 1990 and 1991. Flying squirrel use of Red-cockaded Woodpecker cavities was variable and was not related to presence or abundance of hardwood vegetation. Woodpecker nest productivity was not correlated with flying squirrel use of woodpecker cavities within clusters. In addition, we observed six instances where Red-cockaded Woodpeckers successfully nested while flying squirrels occupied other cavities in the same tree. Our results suggest that complete removal of hardwoods from woodpecker cluster areas in loblolly and shortleaf pine habitat may not provide benefits to the woodpeckers through reduction of flying squirrel numbers. Reduction of hardwood midstory around cavity trees, however, is still essential because of the woodpecker\u27s apparent innate intolerance of hardwood midstory foliage

Retracing the history and planning the future of the red squirrel (Sciurus vulgaris) in Ireland using non-invasive genetics

The Eurasian red squirrel’s (Sciurus vulgaris) history in Ireland is largely unknown, but the original population is thought to have been driven to extinction by humans in the 17th Century, and multiple records exist for its subsequent reintroduction in the 19th 4 Century. However, it is currently unknown how these reintroductions affect the red squirrel population today, or may do so in the future. In this study, we report on the development of a DNA toolkit for the non-invasive genetic study of the red squirrel. Non-invasively collected red squirrel samples were combined with other samples collected throughout Ireland and previously published mitochondrial DNA (mtDNA) data from Ireland, Great Britain and continental Europe to give an insight into population genetics and historical introductions of the red squirrel in Ireland. Our findings demonstrate that the Irish red squirrel population is on a national scale quite genetically diverse, but at a local level contains relatively low levels of genetic diversity and evidence of genetic structure. This is likely an artefact of the introduction of a small number of genetically similar animals to specific sites. A lack of continuous woodland cover in Ireland has prevented further mixing with animals of different origins that may have been introduced even to neighbouring sites. Consequently, some of these genetically isolated populations are or may in the future be at risk of extinction. The Irish red squirrel population contains mtDNA haplotypes of both a British and Continental European origin, the former of which are now extinct or simply not recorded in contemporary Great Britain. The Irish population is therefore important in terms of red squirrel conservation not only in Ireland, but also for Great Britain, and should be appropriately managed

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

European red squirrel population dynamics driven by squirrelpox at a gray squirrel invasion interface

European red squirrel population dynamics driven by squirrelpox at a gray squirrel invasion interfac

Adenovirus: an emerging factor in red squirrel Sciurus vulgaris conservation

1. Adenovirus is an emerging threat to red squirrel Sciurus vulgaris conservation, but confirming clinically significant adenovirus infections in red squirrels is challenging. Rapid intestinal autolysis after death in wild animals frequently obscures pathology characteristic of the disease in animals found dead. 2. We review the available literature to determine current understanding of both subclinical and clinically significant adenovirus infections in free-living wild and captive red squirrel populations. 3. Benefits of scientific testing for adenovirus incorporating both transmission electron microscopy (TEM) and polymerase chain reaction (PCR) technologies are compared and contrasted. We favour viral particle detection using TEM in animals exhibiting enteropathy at post-mortem and the use of PCR to detect subclinical cases where no enteric abnormalities are observed. 4. Adenoviral infections associated with re-introduction studies are evaluated by examination of sporadic cases in wild populations and of data from captive collections used to service such studies. 5. The paucity of data available on adenovirus infection in grey squirrel Sciurus carolinensis populations is documented, and we highlight that although subclinical virus presence is recorded in several locations in Great Britain and in Italy, no clinically significant disease cases have been detected in the species thus far. 6. Current speculation about potential interspecific infection between sciurids and other woodland rodents such as wood mice Apodemus sylvaticus is examined. Where subclinical adenovirus presence has been detected in sympatric populations using the same point food sources, husbandry methods may be used to diminish the potential for cross-infection. 7. Our findings highlight the importance of controlling disease in red squirrel populations by using clearly defined scientific methods. In addition, we propose hypothetical conservation benefits of restricting contact rates between red squirrels and sympatric grey squirrels and of limiting competition from other woodland rodent species

Gastro-intestinal helminths in the red-bellied squirrel introduced in Argentina: accidental acquisitions and lack of specific parasites

Introduced species may lose their natural parasites when invading a new habitat, may acquire new, local parasites or may introduce parasites from their native range. We studied the gastro-intestinal helminth fauna associated with the red-bellied squirrel Callosciurus erythraeus (Pallas, 1778) introduced in Argentina to evaluate its role as a host of either specific or acquired parasites in two invasion foci. We analyzed entire digestive tracts of 72 red-bellied squirrels captured in the main invasion focus (Luján, province of Buenos Aires) between February and May 2011, and in a secondary focus (Cañada de Gómez, province of Santa Fe) in December 2008. We only found two nematode specimens: an adult male belonging to the genus Pterygodermatites (Paucipectines) Quentin, 1969 and another adult male belonging to the genus Stilestrongylus (Freitas, Lent and Almeida, 1973). None of these genera were previously listed for the red-bellied squirrel in introduced areas, but a species of the genus Pterygodermatites was previously reported for this squirrel in its native habitat. These results indicate that, to date, the red-bellied squirrel in Argentina is accidentally parasitised by nematodes acquired in its new environment and has no specific gastro-intestinal helminths. This could be related with a “founder effect” and/or the lack of sciurid rodents that prevent the red-bellied squirrel to be colonized by pre-adapted helminth taxa. Other factors that may play a role are the small number of mammals with arboreal habits and some “encounter barriers” in the new environment that prevent the acquisition of helminths with a wide host spectrum.Fil: Gozzi, Ana Cecilia. Universidad Nacional de Luján. Departamento de Ciencias Básicas. Grupo de Estudios en Ecología de Mamíferos; ArgentinaFil: Guichon, Maria Laura. Universidad Nacional de Luján. Departamento de Ciencias Básicas. Grupo de Estudios en Ecología de Mamíferos; Argentina. Consejo Nacional de Investigaciones Científicas y Técnicas. Centro Científico Tecnológico Patagonia Norte. Instituto de Investigación en Biodiversidad y Medioambiente; ArgentinaFil: Benitez, Verónica Victoria. Universidad Nacional de Luján. Departamento de Ciencias Básicas. Grupo de Estudios en Ecología de Mamíferos; ArgentinaFil: Troyelli, Adrián. Universidad Nacional de Luján. Departamento de Ciencias Básicas. Grupo de Estudios en Ecología de Mamíferos; ArgentinaFil: Navone, Graciela Teresa. Consejo Nacional de Investigaciones Científicas y Técnicas. Centro Científico Tecnológico La Plata. Centro de Estudios Parasitológicos y de Vectores (i); Argentin