272 
Psyche 
[Vol. 88 
species which defend predictable and persistent resources (e.g., 
honeydew from aphids, resources which are patchy in space but not 
in time) and (4) truly territorial species which defend area which has 
potential food resources. These divisions mark some ecologically 
important foraging types within communites. 
Observed Patterns 
1. Nest Defense 
The data suggest that species which display only nest defense fall 
into 4 major groups, depending upon the details of their foraging 
biology. First, some species forage only as solitary individuals for 
food items which a single forager can subdue and retrieve (Group I 
foragers, Oster and Wilson, 1978). Examples of this group include 
most Dacetini, many Ponerinae, and some of the non-leaf cutting 
Attini (Brown and Wilson 1959, Wilson 1971, Oster and Wilson 
1978). 
There is very little applicable data on this group. The frequency of 
dacetine nests in extensive Berlese sampling of a tropical deciduous 
forest fit a Poisson distribution indicating a random distribution 
(Levings, unpublished data), but this sort of data does not differen- 
tiate between the suitability of the site or other important factors in 
the distribution of nests. Certainly there was no indication that nests 
were clumped. The maximum number of nests found was 6 in 84 
0.25 m 2 samples. When a truncated Poisson was fit (0 class 
excluded), the distribution did not differ from Poisson expectation 
(p > 0.5, x 2 test). 
Second, some species may recruit nestmates to food resources, 
but make no attempt to defend them, decamping if another, more 
aggressive, species arrives before the food is retrieved (Group II, in 
part, Oster and Wilson 1978). These species specialize in the rapid 
location and removal of food. Examples include Paratrechina 
longicornis and Tapinoma melanocephalum (Wilson 1971). No data 
on their nest distribution is available, but many are known to form 
small fragmented colonies which move frequently between ephem- 
eral nest sites. 
The third set of species have developed mechanisms for feeding at 
the same resources as other, more aggressive ants, without eliciting 
defensive reactions (Groups I & II, in part, Oster and Wilson 1978, 
Wilson 1971). It is not known how much of a colony’s food intake 
