The last wild grazer : exploring habitat preferences of oryctolagus cuniculus in the Maltese garrigue

Abstract

The European rabbit (Oryctolagus cuniculus, Linnaeus 1758) is the only remaining wild mammal herbivore in Malta, where it has been introduced during Antiquity. The species poses a global conservation paradox, being endangered in its native range but highly invasive elsewhere, in particular on islands. While Malta shares some characteristics with its native habitats, the ecology of the rabbit has never been assessed locally. This study aimed to assess the reality of this paradox in the Maltese context by quantifying the effect of selected habitat parameters of known importance to the rabbit in its native semi-arid ecosystems. A total of 24 sites (1ha each) were surveyed by integrating high-resolution drone imagery and national LiDAR data through supervised SVM classification (kappa = 0.83), along systematic quadrat surveys to measure pellet density. Analysis was performed using separate Generalized Linear Models relating pellet counts with shrub vegetation’s structure (number of shrubs, shrub height and area, aggregation), intra-site land cover composition, and the surface of three anthropogenic features in and around sites (paved roads, hiking trails and rubbles walls), respectively. The extent of paved roads and hiking trails were both negatively correlated to pellet counts and explained together 48% of the variations in pellets across sites. The land cover composition could explain only 26% of the variations in pellets, while the ratio of herbaceous to low-lying shrubs was identified as the main driver negatively correlated to pellet density (marginal R2=0.24). Lastly, the measured shrub metrics did not show significant effects on pellet counts. The findings of this study confirmed the predominant role of human development in Malta for the spatial distribution of the wild rabbit in the remaining open semi-natural habitats. Moreover, it highlighted that human hunting pressure is likely stronger than non-human predation pressure locally. Finally, a key role of the rabbit in the competition between herbaceous and dwarf shrub species in the Maltese garrigue was suggested. These findings have the potential to inform both ecological restoration projects and wild rabbit management in Malta.