Data from: Vegetation structure mediates a shift in predator avoidance behavior in a range-edge population

Where organisms encounter novel conditions during range expansion,
behavioral changes suited to the new habitat can enhance survival.
Behavioral changes that mitigate predation risk are particularly important
for the persistence of range-edge populations, especially where plastic
responses outpace genetic adaptation. We use a climate-driven spatial
mismatch between the arboreal mangrove tree crab (Aratus pisonii) and its
primary mangrove habitat to evaluate differences in predator avoidance
behavior between populations in range-center mangroves and adjacent
range-edge salt marshes. We expected that differences in vegetation
stature and diameter mediate changes in Aratus behavior. We combined crab
and vegetation surveys with tethering experiments and in situ behavioral
trials to determine habitat-specific predation risk and predator avoidance
via evasion and autotomy. Tethering trials revealed that predation risk
was always greater from aquatic sources than terrestrial sources and that
aquatic risk was enhanced in marsh habitat. Vegetation structural form
constrained Aratus predator avoidance during in situ behavioral assays: in
mangroves, Aratus escaped upward into the canopy, but short statured marsh
grass restricted evasion to downward movement towards the higher risk
aquatic environment. Given this restricted evasion route, Aratus in salt
marsh were less likely to evade and showed more evidence of secondary
escape via leg-dropping. Shifting predator avoidance behavior away from a
fleeing escape strategy may ameliorate the fitness costs of reduced escape
opportunities for Aratus in novel marsh habitat along the range-edge.
Similar changes in behavior to match local habitat conditions could be
integral to the persistence of many range-edge populations that encounter
novel habitats.