"Surprising" Phenomenon
Common Eiders lay the eggs in the wooden-box nests rather than the woody-vegetation nests.
Objective
The right answer will be a hypothesis that explains a key difference between the wooden-box nests and the woody-vegetation nests. That difference will result in the wooden-box nests being more attractive to Common Eiders for egg-laying purposes, for some reason other than maximal protection from predators.
A
Some Common Eiders that lay their eggs in nests established by other Common Eiders have been observed, in subsequent years, building nests of their own in the nature preserve.
We don’t care what the Common Eiders did years later. We need to know why they’re choosing nests that aren’t maximally-protected from predation.
B
Established nests concealed in woody vegetation are difficult for Common Eiders to detect.
Common Eiders choose the wooden-box nests because they’re the best-protected option they can find. Woody-vegetation nests are difficult to detect, so Common Eiders choose the next-best option.
C
Defensive behavior by nest builders can sometimes deter intruding Common Eiders.
For this to work, we would need to know that woody-vegetation nest builders are more defensive than wooden-box nest builders. We don’t know that.
D
Virtually all of the island nature preserve consists of habitats that have been, at some point in the past, altered by humans.
The stimulus doesn’t tell us that human alteration makes a difference. Besides, we need something that differentiates the wooden-box nests from the woody-vegetation nests.
E
Foxes and other natural predators of the Common Eider are not uncommon in the island nature preserve.
If predators are common, why aren’t Common Eider choosing the best-protected nests? This simply intensifies part of the paradox in the stimulus.