Ants on Trees: What Trees Do Ants Find Attractive in Urban Areas?

            Urbanization causes a lot of disturbance in the habitats organisms occupy and cause changes in species composition in a certain location. Foreign species may be introduced into a new locality which can form a potential habitat with mixed native and foreign species. General fragmentation of habitat due to urbanization may also mean that these potential habitats can act as refuge for many organisms, including ants. This also offer some challenges to the foraging ants, as the resource structure can be changed. The types of tree species can be especially influential in ant distribution, as ants can be closely associated with their host plant species or switch to another host if there is more honeydew availability (MacArthur-Waltz et al., 2021).

            MacArthur-Waltz et al. (2021) looked into the preference of trees of ant species in California on a college campus. In addition, they also observed if the health condition of trees, seasonality and time of the day mattered to ants. They found ants are overwhelmingly occurring on ever-green tree species in all seasons. Deciduous trees were not as popular. This was the trend in both native and non-native tree species, but ants significantly preferred native ever-green trees more. Ants also preferred healthier trees to some extent, although trees with less rigor ratings also had ants. The authors looked for evidence of resource partitioning among different ant species. They found that different species are most active in different seasons of the year and in different time of the day, suggesting that could be a temporal resource partitioning between different ant species. However, it is unclear if different ant species partitioned the same food resources.

            This article is closely related to our group’s project. It hints that we might be able to find similar patterns in which ants preferred native tree species. It’s doubtful if we can observe the same preference for evergreen trees. In the study by MacArthur-Waltz et al. (2021), the ants were active all-year round and the available evergreen tree species were quite different from the situation in Iowa. However, the authors’ suggestion that ants’ preference for evergreen was due to potentially more consistent resource availability might hold true for our study. Ants preferring healthy trees might also be due to a similar reason. In our study site, where some trees have been damaged sometimes severely by the derecho, this could mean that ants would stay away from damaged trees.

Reference: 

MacArthur-Waltz, D. J., Nelson, R. A., Lee, G. and Gordon, D. W. (2021). Tree Preference and Temporal Activity Patterns for a Native Ant Community in an Urbanized California Woodland. Journal of Insect Behavior, 34, 211-222.