The Mad Biologist loves this experiment. In the April 2007 issue of Ecology, there’s a nice article by Ellis et al. demonstrating how sea gull predation regulates community dynamics in the rocky intertidal. One of the methods used was the construction of exclusion cages. Essentially, these keep various critters of interest out of a patch of seashore (or in, if the researcher prefers).
For example, a cage might be constructed to let prey (e.g., snails) in, but keep predators (e.g., crabs) out. But that’s hard to do with seagulls that eat large crabs: both organisms move long distances rapidly. Covering 100 square meters with wire mesh isn’t any more ‘realistic’ than caging off a 1 square meter area both organisms can cross in a matter of seconds.
So how do you create a “gull exclusion zone?” Here’s how:
Within the control plots, gulls were allowed to forage normally. In gull exclusion areas, 1-3 people prohibited gulls from foraging during low tides by scaring them away using streams of seawater from “supersoaker” water guns, thrown pebbles, and/or noise.
They got to shoot squirtguns, throw rocks, and yell at birds.
And it’s science!