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Randersacker, Germany

Signorile A.L.,Imperial College London | Signorile A.L.,UK Institute of Zoology | Wang J.,UK Institute of Zoology | Lurz P.W.W.,Lurzengasse 3 | And 4 more authors.
Diversity and Distributions

Aim: This study investigates how founder size may affect local genetic diversity and spatial genetic structure of the invasive American eastern grey squirrel (Sciurus carolinensis) in European areas. It also examines whether dispersal propensity and invasion rate may be related to founder size, genetic diversity and structure. Location: Piedmont, Italy; Northern Ireland, Northumberland and East Anglia, UK. Methods: Across the invaded range in Europe, 315 squirrels from 14 locations, grouped in four areas, were sampled and examined at 12 highly polymorphic microsatellite loci. We estimated both genetic variation and population structure using AMOVA, Mantel tests and Bayesian analysis. We also estimated migration rates and range expansion rates. Results: Genetic diversity varied in accordance with numbers of founders across populations. For instance, the Italian population had the smallest founder size and lowest genetic variability, whereas Northumberland had high values for both. Significant levels of genetic differentiation were observed in all the examined regions. Gene flow, migration and population range expansion rate were also higher in England and Ireland than in Italy. Main conclusions: Populations descending from human-mediated releases of few individuals were more genetically depauperate and more differentiated than populations established from a greater number of founders. Propagule pressure is therefore a significant factor in squirrel invasions. There is a trend whereby larger founder sizes were associated with greater genetic diversity, more dispersal, less local genetic differentiation and faster range expansion rate in squirrels. These findings have important management implications for controlling spread rate of squirrels and other invasive species: good practice should prioritize preventing further releases and the merging of genetically distinct populations as these events can augment genetic diversity. © 2014 The Authors. Diversity and Distributions published by John Wiley & Sons Ltd. Source

We present unique footage and an analysis of recorded data of a free-ranging red squirrel building its drey in February 2012 inside a nestbox fitted with a hidden camera. Drey construction occurred over a period of three days that was dominated by an initial phase of transporting material; this then shifted more and more to construction of the outer twigg-shell of the drey and to the processing of materials for the soft inner lining and core of the drey. Total construction time in terms of minutes of red squirrel presence logged was 3.6 hours. Construction occurred after a period of 4-5 days of dry weather and at temperatures that were well above 0° C. After the squirrel abandoned the drey, the dry material was explored and used by songbirds indicating the importance of accessible structures and dry construction material for other species. The video is available as supplemental material in the online version. © 2014 Associazione Teriologica Italiana. Source

Bosch S.,Metterstrasse 16 | Bosch S.,Karlsruhe Institute of Technology | Spiessl M.,Karlsruhe Institute of Technology | Muller M.,Karlsruhe Institute of Technology | And 2 more authors.

Monitoring is a fundamental aspect of species conservation and research. Technological advances, especially with respect to camera trap technologies, have allowed glimpses into unknown aspects of species behaviour and have the potential to greatly assist species distribution monitoring. Here we present the findings of a pilot study combining existing biological monitoring techniques with mechatronics to advance monitoring technologies and develop a multi-purpose, species specific, automated monitoring system. We developed a Small Mammal Monitoring Unit (SMMU) that integrates automated video, and sound recording, carries out body weight measurements and takes hairs samples with a bait station in a portable perspex box. The unit has the potential for use with a range of small mammal species, but has been field-tested here on red squirrels, Sciurus vulgaris, in Germany, Scotland and Switzerland. We successfully collected hair-samples, body mass data as well as video and sound recordings. Preliminary data analyses also revealed behavioural information. Heavier individuals first gained access to the feeder in the morning and have longer feeding bouts. Our prototype demonstrated that the collaboration between mechatronics and biology offers novel, integrated monitoring techniques for a range of research application. The development of units for other mammal species is planned. Future developments will explore the possibilities for wireless data transmission, built-in collection of weather data and collection of images from inside the unit for the recognition of individuals. © 2015 Associazione Teriologica Italiana. Source

White A.,Heriot - Watt University | Bell S.S.,SRUC | Lurz P.W.W.,Lurzengasse 3 | Boots M.,University of Exeter
Journal of Applied Ecology

There is increasing evidence that disease-mediated invasions are widespread across a range of vertebrate, invertebrate and plant systems. We therefore need a better understanding of the role of disease in managing conservation threats due to introduced and invasive species. Here, we develop a general theoretical model framework to assess the impact of disease-mediated invasion on the viability of conserving native species through refuges taking into account explicit spatial and stochastic processes. The model techniques are applied to the well-documented red and grey squirrel conservation system in the UK as a case study. By combining general and specific modelling approaches, we are able to make management predictions while also gaining an understanding of the processes that underlie population outcomes leading to more robust conservation practice. Model results indicate that in the absence of control of the invading species, native populations are driven to extinction both in the absence of disease (through competition) and more rapidly when the disease is included (through competition and disease processes). When control is applied to reduce the abundance of the invading species, there is a threshold in the level of control, above which the invading population can be prevented from establishing and the native species can be protected. Highly virulent infections - squirrelpox in red squirrels - lead to periodic outbreaks of disease in the native population due to continual invasion attempts from the disease-carrying invader. Infections with low virulence may become established at endemic levels in native populations. Therefore, an important finding is that the disease can spread through the native species even when the invading species is prevented from establishing. The benefits of increased density may be countered by an increased risk of disease outbreaks. Therefore, a critical message is that there is a correlation between native density (and therefore habitat quality) and the impact of disease 'harmful' to native species. Control of the invading species to prevent it establishing in strongholds can protect the native species from exclusion, but may not protect it from disease outbreaks. Synthesis and applications. Disease outbreaks in the absence of the invading species can result in significant population crashes and therefore represents a serious threat because it contributes to the risk of population extinction by suppressing the size of the population making it more vulnerable to extinction through stochastic processes. Disease outbreaks in the absence of the invading species can result in significant population crashes and therefore represents a serious threat because it contributes to the risk of population extinction by suppressing the size of the population making it more vulnerable to extinction through stochastic processes. © 2014 British Ecological Society. Source

Rodents are traded as pet species, a practice that frequently results new introduced populations. This is particularly true for tree squirrels where, often, only a few founders can establish viable colonies. Here, we review the worldwide introductions, ecology and impacts of two tree squirrel species, Callosciurus erythraeus and Callosciurus finlaysonii, and discuss the elements of a strategy to reduce squirrel introductions and settlements. C. erythraeus has established viable populations Argentina, France, The Netherlands, Hong Kong and Japan. An introduction to Belgium may have been stopped successfully. C. finlaysonii has been introduced to Italy, Singapore and Japan. After 1950, the mean number of introduction events was one every two years. The most evident damage caused by these species is bark stripping that can be severe and may significantly impact trees and timber plantations. Data on negative impacts to native species are reported but have not yet been formally quantified. Both squirrel species carried with them parasites from the native range into the new habitats, leading to the introduction of other species. The ability of tree squirrels to establish themselves successfully, often from only a few founders, combined with their human appeal make them high-risk species, and the pet trade should be considered as a high-risk pathway for new introductions. A proactive approach to preventing new introductions should therefore include trade restrictions, and should be combined with public education initiatives at national and European scales. Tree squirrels represent an 'alien species conundrum'. Experience from the UK and Italy has shown that if action is delayed until introductions are recognized as a problem, it is generally too late to control populations effectively, due to logistic, legal or economic reasons, or due to lack of public support. the case of new populations, a rapid response mechanism is therefore critical. Once established, populations may become invasive and difficult or impossible to control. © 2011 Mammal Society/Blackwell Publishing. Source

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