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[Vol. 90 
of colony reunification shortly after division by budding. The 
important point in both cases, however, is that adult transport of 
Formica by Polyergus took place in a staggered, prolonged, emi- 
gration-type column, without the intervention of an abrupt, short- 
lived, and full-scale raid. 
That the P. lucidus emigration raids reported in the present study 
are fundamentally similar behavioral processes to their slave raids is 
evidenced by the congruence of several parameters, including: (1) 
the immediate organization of the emerging workers into an organ- 
ized swarm; (2) the time of raid onset; (3) the occurrence of multiple 
raids; and (4) the participation of recently-eclosed Polyergus cal- 
lows. The number of Polyergus workers in the emigration raids was 
lower than that characteristic of most slave raids. This difference is 
probably not significant, because it is known that even slave-raid 
participants decrease to as few as 13-50 individuals towards the end 
of the raiding season (Talbot 1967). Nevertheless, the social context 
of an emigration does produce at least one major difference in the 
behavior of the Polyergus workers. During emigration raids, it is 
principally Formica adults that are carried by the Polyergus. 
Because these adult slaves were reared from the pupal stage in the 
chemical and tactile environment of the mixed nest, the communica- 
tory basis for social carrying behavior is well established. During 
slave raids, by contrast, Formica adults respond to the intruding 
Polyergus by exhibiting various forms of withdrawal behavior (Wil- 
son 1971). Asa result, it is principally Formica pupae and callows 
that are retrieved during slave raids. 
Emigration behavior with adult transport is common in many ant 
species (Smallwood 1982), including free-living colonies of Formica 
schaufussi. Because F. schaufussi is considered related to Polyergus, 
emigrations probably pre-date the evolution of slave-raiding behav- 
ior. The secondary use of raiding behavior for Polyergus colony 
relocation represents an adaptive evolutionary transition, consistent 
with Simpson’s (1958) principle of “transformation.” Accordingly, 
when changes at any level of organization take place during a spe- 
cies’ evolution, previously existing adaptations are often remodeled 
and eventually serve new functions. Because group raiding in 
Polyergus involves a complex recruitment process specialized for 
the efficient retrieval of other ants, it is clearly advantageous for the 
colony to utilize the process in all appropriate behavioral contexts. 
