TEMPORAL ACTIVITY PATTERNS IN 
TWO COMPETING ANT SPECIES 
(HYMENOPTERA: FORMICIDAE) 1 
By James H. Hunt 
Dept, of Zoology, Univ. of California 
Berkeley, CA 94720 2 3 
Most ant species are known to exhibit some degree of patterning 
in foraging rate. Interspecific differences in foraging rate can be 
noted both temporally and, in temperate latitudes, seasonally. Such 
differences can contribute to an effective partitioning of resources 
among coexisting species. The following set of observations documents 
a difference in foraging pattern that may be the significant component 
of coexistence of the two closely competing species observed. The 
system will be described, and possible implications of the observations 
will be discussed. 
The species observed were Dorymyrmex antarcticus and Tapinoma 
antarcticum * , both members of the subfamily Dolichoderinae. Obser- 
vations were made at Fundo Santa Laura, near Til Til, Santiago 
Province, Chile, during October and November of 1971 and 1972. 
The site was at 1,000 m elevation on the east-facing slope of the low 
coastal cordillera. Vegetation was mixed shrubs and annuals forming 
the community known as matorral, which is characteristic of the 
Mediterranean climate zone of central Chile. 
On visits to the site in 1971 I noted that the two species- compete 
strongly for baits. A bait of honey on a small wad of cotton would 
attract Dorymyrmex antarcticus workers when it was placed on the 
ground in the early morning. These workers recruited a. small 
number of nestmates, and activity would continue until midmorning 
when the first few workers of Tapinoma antarcticum appeared. 
These workers, once they located the bait, would quickly recruit 
many of their nestmates, and the many small T. antarcticum workers 
aggressively repelled the fewer, larger, less aggressive workers of 
1 A Contribution of the Structure of Ecosystems Subprogram, International 
Biological Program. 
2 Present address: Dept, of Biology, University of Missouri, St. Louis, 
Missouri 63121. 
3 Generic placement of this species in Tapinoma is almost certainly in- 
correct. Ecologically, the species is similar to Iridomyrmex pruinosum of 
the southwestern U. S. 
Manuscript received by the editor May 2, 1974. 
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