. The Biological bulletin. Biology; Zoology; Biology; Marine Biology. MIGRATION BEHAVIOR OF RED CRABS 307 D / 2 •••* c/ANCA —• /•* Field. Figure 2. Locations of the sites for determining the density of red crabs during February and March 1995 (non-migratory season). Sites A-E were within Study area 1: sites F-L were in Study Area 2. mature regrowth forest, but some were very close to cleared areas. At each station the visible red crabs were counted in each of six grids (9X9 m). All counting was done either in the 2 hours after dawn, a period of foraging activity for red crabs, or during overca
. The Biological bulletin. Biology; Zoology; Biology; Marine Biology. MIGRATION BEHAVIOR OF RED CRABS 307 D / 2 •••* c/ANCA —• /•* Field. Figure 2. Locations of the sites for determining the density of red crabs during February and March 1995 (non-migratory season). Sites A-E were within Study area 1: sites F-L were in Study Area 2. mature regrowth forest, but some were very close to cleared areas. At each station the visible red crabs were counted in each of six grids (9X9 m). All counting was done either in the 2 hours after dawn, a period of foraging activity for red crabs, or during overcast conditions that normally stimulate a similar degree of activity (Hicks. 1985; Green, 1993, 1997). There is very little understory vegetation in the rainforest of Christmas Island, so foraging red crabs are easily visible and provide relatively accurate estimates of the crabs present in the area. Additionally, stations that were populated predominantly by large male crabs were discrim- inated from those with a more mixed population. These data were confirmed as having homogenous variance by using Bartlett's )f test and were then analyzed by analysis of variance (ANOVA: Systat ). Post hoc testing was by Tukey's HSD, and P < was taken as significant in all cases. Activity- patterns. Two separate experiments were con- ducted to determine the activity patterns of red crabs during the non-migrator)' season (March 1993; wet season) at station B within Study Area 1 (for location, see Fig. 2). Firstly, crabs were selected at random and observed for a period of 2 min during their normal foraging activities. The distance that each crab walked during the 2 min was re- corded (n = 15). During the second experiment, the actual walking speed of foraging crabs was recorded. A crab was chosen at random and observed until it started walking; the crab was then timed for as long as it continued to walk, and the distance it traveled was recorded (n = 14). All crabs used i
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