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Psyche 
[Vol. 88 
When such baiting experiments are carried out, there appears to 
be little active defense of the food by Rhytidoponera workers. When 
baits are partially occupied by other smaller but mass-recruiting ant 
species, such as Pheidole, Rhytidoponera workers adopt a “grab- 
and-run” strategy. This is illustrated by the following observations 
on purpurea in rainforest near Cape Tribulation, north Queensland 
(5 June 1980). 
A purpurea colony was located in the trunk of a living palm tree, 
in a cavity 60cm above ground. Workers were foraging down the 
palm trunk and on the adjacent rainforest floor. A small chunk of 
tuna fish was placed on a stone, 1.5m from the palm tree, and close 
to a purpurea forager which soon located the bait. It grasped a small 
piece of the tuna and returned to the nest, dragging the end of its 
gaster along the ground. A few minutes later, a worker (possibly the 
same individual) emerged from the nest entrance and returned to the 
bait by exactly the same trail. By this time, the remaining tuna bait 
was in two pieces, each attended by 2-3 workers of a Meranoplus 
sp. The purpurea worker carefully circled around one piece of tuna 
to an unoccupied corner and grabbed it, inadvertently getting a 
Meranoplus worker at the same time. The two briefly grappled, and 
the purpurea worker dropped the food and retreated several 
centimeters. It then approached the second piece of tuna, edged in 
towards another exposed corner, swiftly grabbed it (this time 
without a Meranoplus worker), and hurriedly departed for the nest 
by a different route. 
Unrecruited workers of the impressa group apparently forage 
randomly, without laying a continuous odour trail, but upon 
locating food they return directly to the nest. It is unclear what 
method(s) of orientation are utilized. Any explanation must take 
into account the observation that foraging occurs nocturnally as 
well as diurnally (at least in confusa and chalybaea). 
Food Diversity and Size 
The great majority of food items collected by impressa group 
workers are small, individual objects brought in by single foragers. 
Eighty-one food items were returned to a single chalybaea nest 
observed over a total of 8 hours (Table 5). Of these, one item (an 
earthworm) was transported by four workers; the remaining food 
items (encompassing 56 arthropods, 17 Ficus seeds or pieces of fruit, 
and 7 pieces of miscellaneous organic material) were carried by 
