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Psyche 
[June 
The intensity is defined as the total number of recruitment perform- 
ances during the entire experimental period, independent how these 
performances were distributed over the nest movings. The continuity, 
on the other hand, is defined as the percentage of nest movings during 
which an individual worker acted at least once as a recruiting ant. 
4) In order to rank degrees of specialization of different workers we 
combined all these parameters in an index which gives us a measure 
of the relative recruitment activity (RRA) of individual ants: 
R 
RRA = -=r 2 - X C. R a is defined as the total number of active re- 
cruitment acts performed by the individual ant; R p is the total 
number of recruitment episodes during which the ant acted as trans- 
portee or tandem follower, respectively, and C is the continuity, as 
defined above. 
The quantitative records gathered for each individual worker dur- 
ing 20 nest movings, are summarized in Fig. 8 and 9. From these 
sociograms it can be seen that, although both species (F. sanguinea 
and C. sericeus) use different recruitment techniques, the social or- 
ganization of their nest movings is basically similar. The nest emi- 
grations are organized by a pronounced system of division of labor. 
There is a relatively small group of workers ( in our colonies 11% 
in F. sanguinea and 6% in C. sericeus ) which were active in 80% 
of all nest moving experiments, and some individuals of this group 
recruited up to 31 nestmates during a single nest emigration. 
This specialized group shows a significantly higher recruitment 
activity in comparison with all the other workers (X 2 -test, p If 0.0 1). 
The sociograms also reveal that even the mover specialists are 
sometimes transported themselves. This is especially the case at the 
beginning of a nest moving, when a single scout ant first recruits 
workers of the specialists’ group. Those recruits subsequently become 
recruiters themselves. For F. sanguinea we recorded at least 7 cases 
where an ant has been carried to a target area and subsequently 
returned to the old nest to become a recruiter itself. The same pro- 
cedure was demonstrated 20 times in F. polyctena. From those data 
we conclude that the carrying act can function as a complete recruit- 
ment procedure, by which the recruited ant is not only brought to the 
target area but also is stimulated to become an active recruiter itself. 
The same, of course, is true for the tandem running technique as pre- 
viously documented (Hblldobler, Maschwitz, Moglich 1974). 
The degree of specialization of division of labor in different colo- 
nies can be demonstrated by ranking the workers according to their 
