There was a time when I was a firm believer of the adage, "it's not the size of your equipment that matters, it's how you use it". However an incident in Los Angeles a couple of years ago made me reconsider my perspective on that subject matter.
My wife, Cynthia, was at work, and I, being retired, decided to go to the Los Angeles Arboretum for some birding. I was busy taking pictures of a Red-whiskered Bulbul using my 100-400 zoom lens when I noticed a pretty lady ogling me from a distance. She had a camera of her own albeit with a "normal" lens and she would occasionally take some shots of the various flora around her. Then her gazes toward me became more frequent and more intense until to my surprise she decided to approach me. She looked at me with desirous eyes and said, "You have a big one! May I hold it?" To say that I blushed with the intensity of freshly cut beef sirloin was an understatement. Flushed and frozen I just stared back at her.
"I just want to know if a tiny woman like me can handle such size", she tried to explain.
"W-wwell, my wife certainly can, and she's just about your size", I stammered. "As a matter of fact it is hers." Whereupon with trembling hands, I handed my camera with the zoom lens to her.
"Oh, it feels good!", she said with satisfaction.
Regaining my composure and trying to conceal my embarassment, I proceeded to extol the virtues of having this type of lens especially when taking pictures of birds (which she said she would be interested in trying.)
The choice of lens has long been the subject that interests most, if not all, of those who would like to go into bird photography. Allow me then to pitch in some of my points of view regarding this matter.
Bird photographers are almost always birders also and to some degree some birders also like taking pictures of the birds that they see. Birds, in general are tiny, active and skittish creatures and to be able to capture good images of them, a long lens is a must. If out on the field and your primary purpose is to see and hopefully photograph as many birds as there are possible to see, then a 400mm lens (but not the one with a maximum aperture of 2.8 - those are monsters!) would be your best bet. They are light enough to be carried along long walks and powerful enough to capture the images of the birds you encounter along the way.
On the other hand, if you intend to pretty much stay put in an area where birds come (or if you are strong enough to lug them around), then a 500mm lens is the equipment for you. These bulky things, by and large, should be mounted on a tripod for stability purposes, which, of course, adds to the setup's total weight. The results, however, fully compensate for the encumbrances of these photographic gear.
I was explaning all these things in even more detail to the lady when she flashed me a quick smile, uttered a quick "thanks!" and left. Jolted by her sudden departure, I looked at the direction she was headed and smilingly shook my head as I realized the reason why. There stood a man brandishing a humongous 500mm lens with an extender looking as virile as any bird photographer with this kind of equipment can get.
Size matters. Really.