I'm really interested in studying courtship displays of a specific bird but I don't know how I can find these behaviors using a systematic methodology.
Which species and which courtship behaviors? There's quite a bit of literature on quantification of multi-modal courtship behaviors. The behaviors themselves will define how you measure them. Give some more details, and we'll help.
I'm Interested to research male-male interactions in avian lek behavior. However I need of a big sample size, but I don’t know how I can find this behavior repeatedly unless by chance