True, many biologists who tested Dr. Kettlewell's findings, though not Dr. Kettlewell himself, used dead moths to test birds' feeding preferences, but it was not done with intent to deceive, and the textbook writers who omitted the detail are at fault for oversimplifying, Dr. Majerus said.
We confirm these results with experimental designs that either monitor movements, vocal responses, or active eliciting of playbacks, and that test birds in isolation or not, with or without visual stimuli accompanying playbacks.
After 120 min (±15 min) test birds were caught in the pre-test pen and in darkness introduced to the start-box.
Parents were firstly tested in a foraging test, where individual test birds each were allowed to feed in an arena containing three types of potential food sources placed in evenly distributed holes in the floor.
Thus, the depolarizing milky plastic board used in our experiment should completely abolished polarization information for our test birds.
Overall, at test, birds showed a left-hemispace bias selecting the location from the left-hand side more often than from the right-hand side (figure 1).
