Density and habitat requirements of introduced Eastern cottontail Sylvilagus floridanus in northern Italy

Following the introductions carried out in late 1960s, Eastern cottontail Sylvilagus floridanus Allen, 1890 rapidly colonized the Po Plain (northern Italy), following the Po River and its tributaries. We monitored a cottontail population using the line-transect method from autumn 2005 to spring 2009 in a 8.2-km(2) study area located along the Po River, and we investigated species habitat requirements by assessing the presence/absence of faecal pellets in 200 randomly distributed plots from September 2006 to August 2007 and by Resource Selection Probability Function through logistic regression analyses and multi-model inference. The cottontail population varied dramatically over time in size, with a great drop at the end of the breeding period. Cottontails selected foraging habitats at the macro- and micro-scales, with some differences among seasons. Two macro-habitat variables differed significantly between used and unused plots through seasons: arboriculture stands were always greater in presence plots, whereas winter cereals were always greater in absence ones. On the macro-level, woody and herbaceous habitats, such as fallow fields, characterized presence plots. At the micro-habitat level, presence plots were associated with permanent dense cover except during summer. Several logistic regression models were built through seasons and ranked using the Akaike's Information Criterion. Arboriculture stands enhanced cottontail presence mostly during the growing season contrary to crop fields. Hedgerows were used according to availability during feeding activity. Cottontail habitat selection varied according to seasonal changes in resource availability and suitability of the different habitat types.