No abstract

European rabbits Oryctolagus cuniculus are a keystone species in Iberian Mediterranean ecosystems. However, the reliability of methods for estimating rabbit abundance, particularly when at low numbers, is not well understood. Further, better standardization of these methodologies would allow abundance estimates to be more reliably compared between areas and periods. Consequently, we compared several frequently used methods of estimating rabbit abundance and assessed their advantages and disadvantages. During the summers of 2008 and 2009, in 11 localities of central-southern Spain we undertook (a) driving transect counts of rabbits, either at dusk or at night, (b) linear transects on foot recording rabbit signs, (c) cleared-plot pellet counts at permanent plots, and (d) standing crop counts, both with and without habitat stratification. Density estimated at night from driving transects using the Distance Sampling method (the reference method against which all other indices were compared) varied from 0 to 2.69 rabbits ha −1 . Most pellet-count indices were significantly related to the reference method. In particular, cleared-plot pellet counts in permanent plots corrected for pellet persistence showed the best correlation with the reference method. In contrast, latrine counts were not related to the reference method index, and we recommend against their use. A standard methodology based on cleared-plot pellets counts could be used to monitor rabbit abundance on a large scale.

We investigate the feeding responses of the red fox (Vulpes vulpes) at a regional scale to different densities of European wild rabbit (Oryctolagus cuniculus) in centralsouthern Spain. Rabbit abundance indices were obtained in 86 localities during summer 2002. The diet of the fox was studied by analysis of 114 scats collected in 47 of these localities. The feeding response of the fox was examined by a representation of the dry weight percent of rabbit in the diet as a function of the abundance of rabbits; this used data only from those localities where at least 3 scats were collected (70 fox scats from 18 localities). We evaluated the relationship between rabbit abundance and the diversity of the diet of the fox. The feeding patterns of red foxes approximated to Holling's type III functional response, typical of opportunistic predators. There was a negative relationship between the diversity of the fox's diet and the abundance of rabbits. Therefore, the fox apparently behaves as a facultative predator, feeding on rabbits when they are abundant and shifting to other prey (and hence a more diverse diet) when rabbits are scarce. These findings are the first step towards understanding the potential role of red foxes in regulating rabbit populations in central-southern Spain.

The European rabbit Oryctolagus cuniculus was designated as a protected species in Spain and Portugal following sharp declines in many populations. The ongoing decline highlights the need to implement cost‐effective management strategies for this staple prey and important small game species of Iberian Mediterranean ecosystems. Habitat management is one strategy in general use, though little is known about its true influence on rabbit populations. The main goal of this study was to assess the frequency of use and cost‐effectiveness of habitat management techniques for European rabbit populations in the Iberian Peninsula. We conducted a thorough literature review and used this information to: (i) estimate the frequency of use of habitat management techniques; (ii) evaluate the relative and absolute effectiveness of habitat management; and (iii) assess the economic implications of its application. At least one habitat management technique was used on over 60% of hunting estates. The relative effectiveness (measured as the % population change before and after management) of habitat management techniques is high, although we found no relationship between high relative effectiveness and rabbit densities considered biologically and/or economically meaningful (e.g. densities able to support a breeding population of endangered predators or medium to high rabbit harvest yields). We did not find any clear relationship between the cost and the effectiveness of the habitat management techniques applied, as the most costly techniques were not the most successful ones. We conclude that rabbit management strategies in the Iberian Peninsula should include improved and upscaled protocols for habitat management, in order to mitigate threats and promote the recovery of rabbit populations.