1981] 
Levings & Traniello — Territoriality in Ants 
285 
Other resources may be similarly affected — for example, winds may 
cover and uncover seeds in the desert (Reichman 1979). The option 
to forage at different times is not uniformly available to ant species; 
thermal tolerances may severely limit foraging time in both cold and 
hot climates or may affect the outcome of foraging contests (Hunt 
1974; Davidson 1977a, b,; Holldobler and Moglich 1980). Many 
species change the time of their foraging in the presence of 
competitors (Hunt 1974, Swain 1977). Thus foraging times may 
separate some species, but as in the case of food or habitat, high 
overlap between sets of sympatric species in foraging time is the 
norm, not the exception, in ant communities. The evolution of 
intra- and interspecific behaviors incuding complex patterns of food 
retrieval and defensive strategies has resulted from such high 
overlap. 
The form and outcome of interactions between species is de- 
termined in large part by the mechanisms of recruitment and 
communication within species. The subtleties of recruitment com- 
munication and their effects on foraging ecology and interference 
competition are not appreciated by most ecologists. Behavioral 
mechanisms are so critical that we suggest that when examining the 
diet of a species, an investigator first ask why more items are not 
included. For many years harvester ants were considered to forage 
individually for seeds, but the field and laboratory studies of 
Holldobler (1976a), Holldobler and Wilson (1970) and Holldobler 
et al. (1978) unequivocally demonstrated that species of Pogon- 
omyrmex and Novomessor rely on a sophisticated array of recruit- 
ment behaviors in foraging. In Novmessor cockerelli, short-range 
recruitment, mediated by both chemical and vibrational signals, 
allows workers to move food sources quickly and thereby enables 
them to compete with sympatric species (Holldobler et al. 1978; 
Markl and Holldobler 1978). 
Behavioral interactions, not food choice, seem to partition food 
resources among generalists. Protein foods (arthropod prey) tend to 
be highly unpredictable in time, space and size; adaptations to this 
resource distribution among generalists may be behavioral rather 
than morphological. Monomorium pharonis and Solenopsis fugax 
employ a chemical interference technique both defensively and 
offensively during foraging (Holldobler 1973). Adams and Traniello 
(1981) have documented the ecological effects of recruitment and 
resource defense in Monomorium minimum, a north temperate 
