Influence of plumage colour on prey response:

The foraging strategies of wading birds may be influenced by their degree of crypsis to aquatic prey. White
plumage has been hypothesized to be adaptive for herons hunting in open water habitats. We tested this
hypothesis with laboratory and field experiments with multiple prey species.We investigated the response
of crayfish, Procambarus spp., and mosquitofish, Gambusia affinis, to white- and dark-plumaged birds in an
experimental chamber. We compared the time spent by a prey in front of a snowy egret, Egretta thula,
mount, little blue heron, E. caerulea, mount, and a control (dowel) with and without backdrop vegetation.
Mosquitofish tended to spend less time under the little blue heron mount with no backdrop present but
made no observable response to either plumage colour against a vegetative backdrop. We assessed prey response
in the field using three drop traps. Each trap had either a little blue heron mount, a snowy egret
mount or a control (dowel) mounted underneath a trap. We compared the amount of biomass captured
between treatments. More prey biomass (mosquitofish, crayfish and anurans) was captured under the control
and snowy egret treatments than under the little blue heron treatment. Our results suggest that dark
plumage may be a disadvantage to herons foraging in open water. In vegetation, structural complexity of