CLUSTERING EXPERIMENT: BNU, 1 Nov 2013


Animal: ants (Terramorium, Caespitum, Linnaeus 1758)

CELL no 2 (26cm x 27cm),  191 ants -> density= 27 per sq.decimeter
CELL no 3 (26cm x 23cm),  377 ants -> density= 63 per sq.decimeter
CELL no 5 (15cm x 27cm),  192 ants -> density= 48per sq.decimeter 
CELL no 6 (15cm x 23cm),  400 ants -> density=117 per sq.decimeter

The numbers of ants were counted on the screen after zooming in.

The strips of paper between the cells are impregnated with citronella oil
which is a well-known repellant for ants (as well as mosquitos). 
However, in the
course of time over a time interval of several hours some ants will
nevertheless cross to
other cells. 
The advantage of these strips over a more rigid container is that the ants 
will mostly stay away from
them whereas they will tend to move to the edge of a container where they will 
then remain. 

What we call a mini-cluster is a a group of at least 3 ants 
which stay together for more than one minute.

Summary: 
After the ants were transferred from their container to the cells, they 
moved faster than usual but some 15mn after the start of the
experiment they slowed down
and started to form a number of loose groups (f1).
In the cells withthe highest density (i.e. 3 and 6) such groups
started to form almost immediately after the beginning of
the experiment.
In the following 30mn, the density of the largest of these groups increased 
(that is to say the ants moved more closely together) and at the same
time the smaler
groups became even smaller until eventually disapearing.

Chronology:
       13:07 -> Start (the camera started to work 10mn later)
f1  -> 13:17 -> Formation of regions with higher density
f2  -> 13:27 -> A number of separate clusters take shape
f3  -> 13:37 -> This process continues
f4  -> 13:47 -> In cell 6 the 3 clusters coalesce into one
f5  -> 14:47 -> Note that in cell 8 which contains only a few ants which ``leaked from 5 into 8
                a small cluster appears nevertheless.
f6  -> 15:37 -> Final picture (not much different from f4 or f5). The experiment is stopped
f7  -> 15:37 -> Closer picture of the cells 3 and 6