I have heard Scott Bourne call bird photography the most difficult kind there is. I do not know if I can necessarily agree with that, as anyone who has tried to photograph a wedding on a super hectic schedule might have a legit disagreement, or done underwater photography, but no doubt when you consider the serious kit you need to even get within range of most birds, it is not a type of photography to enter into casually. For example, this anhinga actually was just standing on the edge of a short pier. Even with a 70-200mm lens and 2x teleconverter on my D300's 1.5 crop sensor, for an effective focal length of 600mm, this is only as close as I could get doing no cropping. The anhinga was maybe 25 feet away. Nikon's true 600mm lens is a $10,000 piece of kit! The lens and teleconverter I borrowed from a friend itself is not that cheap, about a $2,200 solution.
You might be wondering why was I shooting at f/8? Why not shoot closer to the lens' maximum aperture of f2.8? Well, first, the 2x teleconverter automatically makes a f/2.8 lens a f/5.6 lens. Then, I could not get a sharp shot at all with an aperture larger than f/8. It was my first time ever to use that lens as well as the teleconverter, and I was handholding that huge setup, so on at least a monopod I might have been able to stop up a bit.
The anhinga is a very showy bird always willing to dry out its wings for you or, as seen above, flex up. If you do like to do bird photography, Florida is a great place to live, and even Scott Bourne winters here for over a month ever year.