Infrastructure features outperform environmental variables explaining rabbit abundance around motorways

Abstract

Human disturbance is widespread across landscapes in the form of roads that alter wildlife populations. Knowing which road features are responsible for the species response and their relevance in comparison with environmental variables will provide useful information for effective conservation measures. We sampled relative abundance of European rabbits, a very widespread species, in motorway verges at regional scale, in an area with large variability in environmental and infrastructure conditions. Environmental variables included vegetation structure, plant productivity, distance to water sources, and altitude. Infrastructure characteristics were the type of vegetation in verges, verge width, traffic volume, and the presence of embankments. We performed a variance partitioning analysis to determine the relative importance of two sets of variables on rabbit abundance. Additionally, we identified the most important variables and their effects model averaging after model selection by AICc on hypothesis‐based models. As a group, infrastructure features explained four times more variability in rabbit abundance than environmental variables, being the effects of the former critical in motorway stretches located in altered landscapes with no available habitat for rabbits, such as agricultural fields. Model selection and Akaike weights showed that verge width and traffic volume are the most important variables explaining rabbit abundance index, with positive and negative effects, respectively. In the light of these results, the response of species to the infrastructure can be modulated through the modification of motorway features, being some of them manageable in the design phase. The identification of such features leads to suggestions for improvement through low‐cost corrective measures and conservation plans. As a general indication, keeping motorway verges less than 10 m wide will prevent high densities of rabbits and avoid the unwanted effects that rabbit populations can generate in some areas.

The Presence of Rabbit Warrens in an Agricultural Landscape is Related to Patch Features and Distance to a Highway

“…The pattern of rabbit abundance in relation to roads seems to be case specific, modulated mainly by the surrounding landscape. The highest rabbit densities near the roads crossing agricultural fields (Barrio et al 2011, Planillo and Malo 2018, Delibes-Mateos et al 2018) were found in landscapes where the agricultural activities have triggered the loss of predictable and safe habitat for warren construction. In this type of agricultural landscape, roads could play a relevant role where rabbits may proliferate and even become a pest (Barrio et al 2010, Ríos Saldaña et al 2013, Delibes-Mateos et al 2014, 2018) since they are compelled to move along road verges to adjacent crop fields in search of new food resources.…”

“…In agricultural landscapes, space available to warrens is limited to not ploughed natural remnants and, therefore, can set a limit to rabbit populations (Barrio et al 2011). And even more, roads can also modify the presence of warrens (Barrio et al 2011, Planillo and Malo 2013, 2018). We have specifically assessed the occurrence, abundance, and number of entrances of rabbit warrens in natural vegetation patches within an agricultural landscape crossed by a highway.…”

“…The density of rabbit warrens has been reported to be both higher (Barrio et al 2011, Planillo and Malo 2018) and lower (Planillo and Malo 2013) close to a road. Therefore, we have specifically aimed to assess if features of habitat patches and distance to the highway affected: (1) the presence of warrens; (2) the variation in the number of warrens; (3) the number of entrances to the warren; and (4) the spatial distribution of warrens within each patch.…”

Evaluating the Urban-Rural Differences in the Environmental Factors Affecting Amphibian Roadkill

“…For predictive variables reflecting the 'exposure' aspect (i.e., potential amphibian distribution), we included the 19 bioclimatic variables derived from the WorldClim database (http://www.worldclim.org; accessed on 23 May 2021), since previous studies have linked them to potential distributions of amphibian species [40,41]. In addition, we included the Normalized Difference Vegetation Index (NDVI) as an additional environmental variable since it has been used as a successful predictor of the amphibian species richness [42], and the biological characteristics of vertebrates, including species richness, abundance and distribution, and landscape connectivity [27,[43][44][45]. We calculated the average NDVI derived from the MODIS/Terra Vegetation Indices Monthly L3 Global 1 km SIN Grid V006 (MOD13A3v006), obtained from the Level-1 and Atmosphere Archive and Distribution System Distributed Active Archive Center (LAADS DAAC) website (https://ladsweb.modaps.eosdis.nasa.gov/; accessed on 19 September 2021).…”

The selection of anthropogenic habitat by wildlife as an ecological consequence of rural exodus: empirical examples from Spain

“…Many attempts to restock rabbit populations have been implemented but have failed to reverse the decline in natural areas (Carro et al, 2019). On the contrary, wild rabbits thrive in some anthropic areas, building communal dens in apparently low-quality places such as the banks of roads and railways or the median strips of highways (Planillo and Malo, 2017), even inside large cities such as Madrid. Two explanations are possible for this puzzling situation: a) fenced highways and high-speed railways provide protection against predators, and b) road and highway verges create open areas where grass grows.…”