6 
Psyche 
[Vol. 95 
were marked. Marked ants observed on nests were moving about 
without interference from other ants present. On five occasions, ants 
marked on other mounds were observed entering nests. Workers 
often travelled great distances between nests. For example, the 
worker from nest #4 found on #39 would have had to traverse over 
120 m of trail between the two nests, which were about 112 m apart. 
Although there was considerable movement of workers among 
nests, the pattern of crossovers was non-random. The nest censusing 
described above included nests that were not connected to each 
other via trails. While all of the ants were marked on nest group A, 
only 20 of the surveyed nests were within this group. Of the remain- 
ing nine, one (#34) was in group B, three (#3, #7, and #8) were in 
group C, two (#41 and #42) were in group D, and three (#1, #2, and 
#28) were not connected by trails to other nests during the course of 
the study. Ants marked on nests in group A were rarely found on 
nests of other groups (Table 1). Of the 88 different crossovers noted 
above, 86 were between nests within group A. The exceptions were 
an individual from nest #4 found on nests #7 and two from nest #29 
found on #28. Thus, fewer than 1% of the 405 marked ants recap- 
tured on nests other than those on which they were marked were 
found on nests outside of group A. Apparently, workers from nests 
in group A rarely mingled with those from other trail systems, pos- 
sibly because they do not travel the distances separating different 
trail systems or because workers will not tolerate the presence of 
workers from other colonies. 
Crossovers among nests within group A were also non-random. 
The movement of workers among nests was asymmetrical. For 
example, while only two workers from other nests were seen on nest 
#29, 142 marked workers from #29 were found on 14 other nests 
(67% of those censused). The opposite was true of nest #11: 68 
workers from seven other nests were found on this nest, while only 
13 workers from #1 1 were found on seven other nests (33% of those 
censused). In addition, marked workers did not distribute them- 
selves evenly among nests to which they had transferred. For exam- 
ple, of the 142 workers from nest #29 found on 14 other nests, 121 
(85%) were found on just five of these mounds. 
Out of the total of 1300 ants marked with single dots of paint on 
the abdomen (described in methods section as marking procedure 
#1), 313 (42%) were recovered in the nine subsequent surveys. Of 
