Irruptive populations of rodents cause damage to agriculture worldwide. By the end of the last century, the distribution range of Microtus arvalis in NW Spain greatly expanded to encompass agricultural habitats. Crop damaging population outbreaks were reported for the first time. However, the absence of long term vole monitoring data have so far precluded outbreak forecasting, which might help mitigating associated bioeconomic costs. We describe vole expansion and outbreak dynamics in NW Spain based on non-standard and diverse sources of information, including daily newspapers. We illustrate a rapid (< 20 years) and large scale (ca. 5 million ha) colonization of agricultural lowlands, and suggest a pattern of westward expansion emanating from peripheral mountains. Crop damaging outbreaks directly followed range expansion and our analyses indicate that they have occurred at approximately 5 year intervals since the early 1980s. This is the first description of long term (>40 years) regional scale vole dynamics reported for the Iberian Peninsula. We suggest that expansion from (humid) mountains to (dry) plains may be related to recent changes in land use. If confirmed at a local scale, the apparent cyclicity of outbreaks would provide a basis for forecasting outbreak risk in NW Spain and may help local managers adjust current control strategies.

The installation of nest boxes provides nesting sites for barn owls and kestrels. Kestrel populations increased faster than in areas without artificial nests, and the common vole was one of their main prey during the breeding season. The results suggest that local (field) effects could be found in terms of reduced vole density. If so, this could be an environmentally friendly and cheap vole control technique to be considered on a larger scale.

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The common vole, considered a rodent pest when overabundant in agricultural areas, was traditionally absent from the agricultural plains of Castilla-y-León, NW Spain. However, it rapidly invaded ca. 50.000 km 2 of agricultural land, where regular outbreaks have caused crop damages and conflict with farmers. To better understand the factors that triggered this massive invasion of previously unoccupied habitats, we studied the associations between the common vole range expansion and changes in climate and land uses in the region since the 1970s. We found long-term trends in climate, with some changes that could have helped the range expansion (increased fall precipitation and winter temperature) and other changes that may have impaired it (reduced precipitation and increased summer temperatures). Dramatic changes in land use also took place prior to and during the invasion period (marked increases in irrigated and green herbaceous crops such as alfalfa, which are amongst the most favourable habitats for voles). We found strong associations between changes in vole distribution and the extent of green crops (irrigated crops and alfalfa) at regional level. The probability of a given agrarian county to be colonized increased with the extent of green crops, particularly so when vole presence in neighbouring counties was lower, and tended to decrease with increasing livestock abundance. Land use changes, especially increases in irrigated crops and alfalfa, appear to be one of the main drivers behind the range expansion. We discuss these findings in relation to the social conflicts and management challenges that arose from the recent invasion of agricultural areas by crop-damaging common voles.

This paper reports analyses of a capture-markrecapture (CMR) dataset of 149 Azores Bullfinches ringed on São Miguel island (Azores) between 2005 and 2007, and recaptured-resighted on a monthly basis over a 4-year period (2005)(2006)(2007)(2008) throughout their breeding range. We examined the effect of time, age (adults vs. juveniles), gender (adult males and females), and environmental covariates (temperature, rainfall, NAO index) on survival probabilities. The modelling found a high and constant monthly survival probability (mean ± SE) estimated at 0.96 ± 0.01, similar between both adults and juveniles and independent of environmental conditions and gender. These findings agree with expectations from island-based life-history theory where relatively mild conditions and lack of predators should favour high survival rates to compensate for the low reproductive output. The annual survival rate was estimated at 0.62, which was also consistent with this pattern when compared with survival estimates of mainland bullfinch and passerine species on other subtropical islands obtained in similar CMR studies. Based on a canonical estimator, the size of the studied population (mean ± SE) was estimated at 1608 ± 326 individuals. Given that the population size was only around 120-400 individuals in the early 1990s, we suggest that the high survival probabilities currently applying to this critically endangered species may have substantially contributed to the recent recovery of this population. Future research studies on the species' demography should continue to monitor survival in order to measure the effect of management interventions currently taking place within the range of the Azores Bullfinch, including the restoration of the biodiversity rich laurel forest, but also focusing on nest success, which is important for understanding population dynamics.