How moles contribute to colonization success of water voles in grassland: implications for control

Abstract

Summary 1.Outbreaks of the water vole Arvicola terrestris cause severe damage in grasslands of upland regions of Europe. The sheer speed of this phenomenon is a challenge to effective pest control measures. While there has been some research into factors that promote outbreaks, especially landscape composition, little is yet known of the biological mechanisms underlying the speed of colonization of grasslands during the population growth stage. Like A. terrestris , the mole Talpa europaea digs vast tunnel networks that may be used by A. terrestris . The availability of extensive networks of this sort might greatly boost the colonization potential of A. terrestris and so explain the speed of onset of its outbreaks. 2. Areas occupied by networks of A. terrestris and T. europaea tunnels, and their respective locations, were evaluated and mapped with a global positioning system (GPS) during lowdensity, growth and the first weeks of abundance phases of cyclic fluctuations of A. terrestris . 3. During the growth phase and the first weeks of the abundance phase nearly 80% of new A. terrestris colonies were found in T. europaea tunnel networks, although these occupied just 20% of the area under study. 4. The regulating influence of wooded areas on the risk of outbreaks, which can be identified at larger spatial scales (region, sector), was imperceptible at local scales, probably because of the influence and relative extent of T. europaea tunnel networks. 5. There was a threshold level of occupancy of grassland by T. europaea , as indexed by surface indices, below which A. terrestris populations were regulated naturally and over long periods. 6. Synthesis and applications. These findings have implications for controlling outbreaks of A. terrestris . Temporally, chemical pest control of A. terrestris can be reduced by taking action during the A. terrestris low-density phases, preferably in the autumn. Spatially, control operations should be targeted at T. europaea and early A. terrestris networks. Mechanical destruction of tunnels (e.g. ploughing) and trapping should be considered as an alternative to chemical pest control.

Modelling and spatial discrimination of small mammal assemblages: An example from western Sichuan (China)

“…Firstly, numerous species have been shown to respond to landscape level effects whereby densities respond to composition or structure of landscape in a surrounding neighbourhood. Examples include Tetrao urogallus (Graf et al, 2005), Echinococcus multilocularis (Giraudoux et al, 2003), Arvicola terrestris (Fichet-Calvet et al, 2000; Giraudoux et al, 2007; Morilhat et al, 2007) and Microtus arvalis (Delattre et al, 1999, 2006; Duhamel et al, 2000), the latter two being small mammal species of the sub-family Arvicolinae . Here effects of composition and structure in buffers surrounding traplines were not considered, largely due to identifiability issues associated with the required increased level of data mining and the small sample size.…”

Spatial and temporal ecology of the Lusitanian pine vole (Microtus lusitanicus) in a Mediterranean polyculture

“…We also know that M. lusitanicus and T. occidentalis must share tunnels or burrows because in other study areas we have caught both species in the same trap. It is thus possible that voles used mole tunnels (occupied or abandoned) for underground movements, as also described for Microtus multiplex , M. savii (Salvioni, 1988 ) and Arvicola terrestris (Delattre et al, 2006 ). Th us, the availability of an underground pathway and a probably over-dispersed spatial distribution of resources could explain the larger home ranges and high daily distances travelled by M. lusitanicus .…”

Using presence signs to discriminate between similar species

“…This has stimulated works aimed at validating the use of presence signs as indicators of relative abundance of small mammals (Liro 1974;Mankin-Rogalska et al 1986;Giraudoux et al 1995;Fichet-Calvet et al 1999;Van Horne et al 1999). Consequently, the use of presence signs is now widespread among small mammal ecological studies, namely, for our study species (Borgui & Giannoni 1997;Mira & Mathias 1994), for Microtus cabrerae Thomas, 1906(Santos et al 2005Pita et al 2006), Microtus arvalis Pallas, 1778 (Delattre et al 1996(Delattre et al , 1999, Arvicola sapidus Miller, 1908(Fedriani et al 2002, Arvicola terrestris Linnaeus, 1758 (Giraudoux et al 1997;Duhamel et al 2000;Fichet-Calvet et al 2000;Delattre et al 2006), Psammomys obesus Ctretzschmar, 1828 , Talpa europaea Cabrera, 1907 (Delattre et al 2006), Cryptomys zechi Matschie, 1900 (Yeboah & Akyeampong 2001) and other species (Giraudoux et al 1998). We defend the importance and urgency of developing and validating methods, such as using presence signs only, that allow a rapid assessment of species identity in the field, avoiding the logistical constraints of trapping.…”