In social ungulates, the proportion of time devoted to vigilance is a function of group size (known as the group size effect). We studied how varying levels of human disturbance influence this function in the mountain gazelle (Gazella gazella) along the southern coastal plain of Israel. Based on current theory, we predicted that changes in the slope of this function should be associated with changes in average group size. In heavily disturbed areas, individual vigilance levels increased in the bigger groups, causing the vigilance vs. group size curve to flatten, i.e., vigilance was high in all group sizes. Consequently, and in accordance with theory, we found a negative relationship between group size and human disturbance. Specifically, we found that in open areas with low disturbance levels, gazelles were in bigger groups than in open areas with high disturbance levels. In social species, the disruption of behavioral patterns by increased human presence can affect their social structure. Because social structure is a key component in the evolution and dynamics of social species, its disruption by human disturbance can have a considerable effect on population performance even if the disturbance does not directly impact survival and reproduction. Social disruption due to increased access to natural areas should be an important consideration in managing fragmented landscapes.

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The ecological consequences of homogenization remain relatively unexplored. One example of landscape-homogenizing is the establishment of plantations. We studied the effect of human-made forests by contrasting plant and small-mammal community composition between planted tree stands and adjacent natural habitat in two different Mediterranean habitats in Israel: (1) inland habitat where we focused on pine (Pinus halepensis) and carob (Ceratonia siliqua) stands, and (2) coastal sand dune habitat where we focused on planted acacia (Acacia saligna) stands. We first wanted to verify whether planted trees modify plant species composition, and second, if and how the small-mammal community is affected by the different habitat conditions created in plantations with different canopy cover. We were especially interested in the abundance of the commensal house mouse (Mus musculus). All tree stands underwent biotic homogenization indicated by abundance of house mice coupled with lower diversity of indigenous vegetation and small-mammal abundances and diversities. Habitat structural diversity was positively related with small-mammals diversity and was lower in artificial tree stands in both habitats. Our results suggest that using the abundance of commensal generalist species such as the house mouse relative to other more specialist small-mammals is a good approach to determine ecosystem integrity. Precommercial thinning treatment is a potential management tool to maintain a proportion of native tree species within the canopy of planted tree stands. However, until sufficient data is available for making generalizations, the exact level of thinning necessary to reverse the homogenization processes in man-made plantations and keeping indigenous small-mammal communities diverse and less prone to invasion must be determined empirically.

We studied the impact of proximity to human concentrations, hikers, and field vehicles on mountain gazelles (Gazella gazella gazella) space-use patterns, flight distance, and visibility in the southern coastal plain of Israel. We collected data on gazelle behavior and human disturbance from fixed observation sites, drive counts, and pellet counts. The density of pellets was positively correlated with the distance to human concentrations, and the flight distance was positively correlated with human disturbance level, suggesting mountain gazelle space use and flight distance were affected by human disturbance. Gazelles were less visible in the more disturbed areas. Our findings provide a framework for conservation measures such as determining the size of buffer zones and where and when enforcement efforts should take place to keep mountain gazelle populations viable in spite of the ecological impacts of human encroachment on mountain gazelle habitat. JOURNAL OF WILDLIFE MANAGEMENT 69(4):1683-1690; 2005