I want to know the answer to the following question:
What shape is the cage in the Emlen funnel?
All the background I'm provided with is that "Orientation behaviour studies have been traditionally carried out using variants of a setup known as the Emlen funnel, which consists of a circular cage with the top covered by glass or wire-screen so that either the sky is visible or the setup is placed in a planetarium or with other controls on environmental cues.". Is that enough to answer the question?
Answer: yes