Spatial and seasonal variation in occupation and abundance of common vole burrows in highly disturbed agricultural ecosystems

Abstract

Understanding how species respond to disturbance in human-modified ecosytems is critical for management and conservation of biodiversity in the Anthropocene. In agroecosystems, human disturbances severely modify the habitat of species, particularly for those that live in burrows. The common vole Microtus arvalis (Pallas, 1778) is a semi-fossorial microtine, which often exhibits large abundance fluctuations, becoming an agricultural pest in peak years. We evaluated how both agrarian disturbances (via types of crop and their management) and landscape heterogeneity influenced the abundance of common vole burrow systems along a yearly cycle, at the field and landscape scales. We seasonally recorded the number of burrows and their recent occupation in circular plots of 200-m radius including different types of crops in intensified agrarian landscapes in NW Spain. Our results showed a marked seasonal and spatial pattern in both total abundance and abundance of occupied burrows. After a population peak year, only 31% of burrows were occupied across the year (from 41% in spring–summer to 12% in autumn). The crop type and its management in relation to soil disturbance were the main factors driving seasonal and spatial dynamics of burrow abundance at the field and landscape scale. Alfalfa fields held the highest abundance of both total and occupied burrow systems across the year, while fields of traditional-tilled cereal retained the lowest. As a result, at the landscape scale, plots with a greater surface devoted to traditional cereal crops maintained a lower relative number of burrow systems. Regarding the landscape structural heterogeneity, plots with longer length of field margins and lower area of watercourses maintained higher abundance of burrow systems. An adequate landscape-scale planning of crop types, agricultural practices, and distribution of non-crop habitats could be a promising sustainable method to reduce the risk of crop-damaging vole plagues.