Physiological tolerance of species to temperature, moisture or chemicalphysical properties of the soil could be important in determining the distribution and abundance of ant nests. In the present study we investigated the possible differences in the nesting site microhabitat characteristics of two syntopic species of harvester ants of the genus Messor living in a Mediterranean homogeneous grassland area belonging to a single phytosociological association known as "Vulpio ligusticae-Dasypyretum villosi". We tested to see whether the activity of the colonies of the two species directly altered the microhabitat characteristics of the nesting sites. Microhabitat characteristics were assessed quantifying several abiotic factors (light, temperature, soil moisture, soil pH, nitrogen) by means of the Ellenberg Bioindication Model. The model represents a simple way of interpreting the vegetation pattern in terms of ecological factors from the perspective of the plants and can be considered an effective and promising approach to link animal and plant ecology. Our data showed significant differences in the nesting site microhabitat characteristics partially due to a different capacity of the two species to alter nesting site proprieties. Possible differences in the physiological tolerance of these species to moisture gradients could be crucial in determining the distribution and abundance of their nests.

The eastern cottontail Sylvilagus floridanus has been introduced to Italy for hunting purposes since the 1960s. This species is currently present in northern Italy, with some small populations in Central Italy. Data for Central Italy are scanty, but they deserve research attention because this lagomorph is responsible for the spread of disease to an endemic vulnerable species, the Apennine hare Lepus corsicanus. In this work, we summarized the distribution of alien cottontails, over 50 years after their first releases, with special regard to areas where the endemic species is present. Eradication should be recommended where the alien species coexists with the endemic one.