|Whitford, Walter - NEW MEXICO STATE UNIV|
Submitted to: Sociobiology
Publication Type: Peer Reviewed Journal
Publication Acceptance Date: December 1, 1999
Publication Date: December 1, 1999
Citation: Whitford, W.G. Seasonal and diurnal activity patterns in ant communities in a vegetation transition region of southeastern New Mexico (Hymenoptera: formicidae). Sociobiology. 1999. v. 34(3). p. 477-491. Interpretive Summary: There are several variables that affect the abundance and distribution of ant species such as latitude, climate, vegetation, competition, and degradation of the landscape. There are fewer variables that affect the seasonal activity of ants and times of day when ants are active, such as food availability, food stores in the nest, and climate. For this study, the densities and abundance of ant colonies were estimated in three habitat types: creosotebush shrubland, grassland, and mesquite dunes. The research area was in a transition region between the Chihuahuan Desert and the southern Great Plains. Because this area is a transition region, a higher number of different ant species were expected. However, the number of species found (8-12) was considerably lower than in Chihuahuan Desert ant communities. The ant species Forelius pruinosus was the most abundant. Harvester ants exhibited different seasonal patterns in the three habitats. In order to observe the foraging behavior of the ants, several baits were set out, including honey, tuna, and peanut butter. Several ant species extended their usual foraging times to visit the baits. Most ants cannot tolerate soil temperatures above 50 degrees Centigrade. However, one species of an exhibited high-tolerance foraging behavior by visiting the baits when soil surface temperatures exceeded 40 degrees Centigrade. This study suggests that soil surface temperature is the most important variable affecting the foraging activity of ants in arid regions.
Technical Abstract: The densities of active ant colonies were estimated in three habitats: creosotebush shrubland, grassland, and shinnery-oak mesquite dunes. Diurnal foraging patterns were studied at bait boards. Species richness of ant communities in this transitional region (8-12 species) was considerably lower than Chihuahuan Desert ant communities in an area with lower annual average rainfall. The numerically dominant species was Forelius pruinosus. Crematogaster spp. Was subdominant in all of the habitats and exhibited relatively constant activity throughout the growing season. Harvers ants, Pogonomyrmex spp. Exhibited different seasonal activity patterns in the three habitats. One species, Trachymyrmex septentrionalis, was not recorded until October, when its nests were conspicuous with discarded leaf fragments around the entrances. Several species of ants feeding at bait board extended their foraging times in comparison to colonies of the same species too distant from the bait boards for foragers to reach the baits. Only one species (Pogonomyrmex apache) exhibited a high-tolerance foraging behavior by initiating foraging at the bait boards after soil surface temperatures exceeded 40 degrees Centigrade and other species had ceased foraging. Foraging activity of most species continued throughout the day when cloud cover reduced soil surface temperatures to 40 degrees Centigrade during midday.