Bird sight

If we think that we have a keen sense of bird presence, we are greatly mistaken.  Bird sense, that's how I term how a bird can quickly sense us, however far we are, especially when we have a lens trained on it, is astounding.  (We bird watch and birds sense.)
     According to Tim Birkhead, a professor at the University of Sheffield UK, who researches into understanding lives of birds, "some birds can see behind them, others see UV or great distances, and a few can even “see” with sound".

This shot was taken at a distance of more than 400mm, yet the Pink-necked Pigeon instantly sensed my lens on it.

However, I guess we can learn to sense quickly birds too.
I was pleasantly surprised to find that my following shots managed to nab the bird quite nicely, despite the thick foliage: