Now I'm not a nature photographer, so I don't have zoom lenses larger than 300mm; wish I did, but it would be a little silly trying to use a 400mm or larger lens in a church or reception hall. So I have to count on luck more than equipment to get me close to my subject. And sense that doesn't happen all too often I have my 70-300mm by my side to get the best shots available. Another thing I don't do is use a tripod like real nature photographers do; with the weight and zoom of those lenses, that's the only way they'll keep a picture in focus.
I once saw, close up, a zoom lens that easily could've been 600mm -800mm, maybe even larger. It was huge, and the guy had it propped up on the car door window as he sat behind the steering wheel. I would love to have seen one of his pictures just to see what that lens could do. In some of the restaurants in town the walls are donned with art by local artist; whether it's a photograph, oil or acrylic painting, all of them were exquisite to behold. Sometimes that's the best part of going to the restaurant, and not so much for the food; I do have a restaurant in mind as I say this.
I've had the good fortune to sell some of my nature photography also to a bed and breakfast in town. I was also hired by them to take interior photos that promote their business online. He just fell in love with my galleries of the nature photos, and ended up purchasing several. Made me happy, it was the first time I sold anything other the my normal business portfolio. So I take nature photography more seriously now and incorporate an artistic quality in them with hopes of selling more.
I hope you enjoy my nature photos as much as I did taking them. Ciao.