Arthropod diversity on Bird island was surveyed
on 4th and 5th April 2001, 21–23rd October 2001
and 20–22nd October 2002. During each visit,
10 samples of leaf litter, each covering 1 m2, were
collected from an A. gracilipes free area and an
infested area (points A and B in Figure 2). These
sites differed primarily in the presence or absence
of the crazy ant. Both were areas of woodland,
details of comparisons of vegetation and tree
cover are given in Table 3. All leaf litter types
were sampled, for samples from coconut woodland
the superficial layers of leaves were removed and
the partially decomposed sub-surface leaves used.
The superficial layers did not support invertebrate
life as revealed by careful examination of leaves
outside of the sample quadrats. These samples
were sieved and placed in Tullgren funnels for
24 h. Sweep netting of 10 m2 was also carried out
in these two areas. In October 2002, no A. gracilipes-
free woodland could be found, and 20 leaf
litter samples were collected from randomly
selected grid squares. For each sample, the invertebrate
composition, litter depth, canopy cover and
distance from the sea were recorded. The association
between invertebrate numbers and crazy ants
was analysed using a multiple analysis of covariance
of crazy ant numbers, canopy cover and
minimum distance from the sea.