What factors do they weigh on? Shape, position of branch within the tree body/structure, fatigue, nearness to current position, etc.

And how fast does a bird's brain and nervous system decide on this?

Narrowing it down to a bird of prey, say the Harpy Eagle.

  • $\begingroup$ I think that the question is too broad. There are over 10000 species of birds and the majority of them uses branches to perch. The reasons/ motivation can be so many that your question should be targeted to more specific situation to be able to provide an answer. $\endgroup$ – have fun Feb 20 '17 at 8:17
  • $\begingroup$ I agree it is fairly broad question, but, nevertheless, I'm sure the OP would benefit from a brief discussion (or the very least a list of potential sources to read) examining/reflecting on this question for any species. I wonder myself if anyone has tried to model/determine these behaviors. I vote to keep this question open. $\endgroup$ – theforestecologist Feb 21 '17 at 22:03
  • $\begingroup$ @theforestecologist thanks for the upvote. I understand that the question is too broad in a sense. But my question was directed towards the basic premises of a bird's cognitive decision making. Let me narrow it down to a certain species within the wide classification of birds of prey in that case. $\endgroup$ – Aurodeep Ghosh Feb 26 '17 at 6:11
  • $\begingroup$ Btw, I found this for a start. asifg.mycpanel.princeton.edu/publications/pdfs/… $\endgroup$ – Aurodeep Ghosh Feb 26 '17 at 6:14