Be an Ethical Nature Photographer
There is an ethical responsibility in being a nature photographer. Your camera is a tool, not a license. It gives you responsibility, not a right to interfere with others. Everyone has a right to enjoy the natural world as they wish to do so. Whether you use the camera to create and sell images or create memories, saying "please" and "thank you" will go a long way to helping you gain the photographic opportunity you are hoping for. Rude and bossy attitudes as you push through a crowd will guarantee to unite others in your group against you.
If you travel by yourself to national parks or other places where you are likely to encounter other travelers, plan your time so you can photograph when crowds are less likely to be around. Some locations are off limits to visitors to protect fragile habitats, nesting birds, or historical landmarks. Obey the rules. There may be a thousand people a day who would like to make the same image and in doing so destroy the habitat of a rare plant or disturb a nesting bird. (I have seen photographers kneel on top of a rare orchid in order to get a better shot of the orchid they were photographing.) Everyone has an excuse why they should be the exception to the rules.
Because of careless photographers, all photographers have developed a reputation for doing whatever they need to do to get a photo, regardless of the problems they cause.
I was on a tour bus in Denali National Park in Alaska one summer and as we passed a photographer making some images the driver announced that we were passing the biggest threat to wildlife in the park, photographers. He gave his opinion of how photographers would do anything for their shot and should be banned from the park. The driver was wrong about photographers in general, but right about some photographers he had seen. Unfortunately, good photographers go unnoticed. Although I tried to correct the driver and explained that all photographers were not the same, there were about thirty people on that bus who left the park thinking that something should be done to curtail the behavior of photographers.
The most important reason for knowing your subject is to get images of wildlife being wild, not reacting to you. Ensure that your impact on the subject does not cause it harm now or in the future. No matter how much money you have spent and how many miles you have traveled to be at the location, no photo is worth risking the well being of the subject.
Some photographers will "garden" if the setting is not just right. This can have dire consequences for wildlife. "Gardening" is when you cut or remove vegetation in order to help the composition of the photo. This is especially disconcerting when photographers are working around nests and dens of wildlife. There is a reason the animal chose that particular site to build it's home, and often that reason is because of the protection branches or other vegetation around it offer. If you must remove a branch or other obstruction for the photo, tie it back. Do not cut it or pull it out by the roots. This way, after you are through, you can put everything back the way it was when you found it.
It is not true that if you put a chick that has fallen out of a nest back into the nest the parent bird will abandon the chick because of human smell. However, you should be aware that odors we introduce can open a nest to predation. If you leave any food at your photo site, predators (like a fox) might be attracted to the food and find a nice juicy group of chicks in the nest instead.
Before you work at a den or nest, you must be aware of the tolerance level of the subject. Some birds and animals have high tolerance for you photographing them, others may not. If you cause the parent bird to be away from the nest too long, that may cause the chicks to become cold or over-heated. Young animals need to be fed on a regular basis. If you prevent the parent from feeding it's young, you may seriously threaten the young animal.
Photographing animals at their home is the exception to the rule that you should think of your equipment in terms of what it can do and not what its limitations are. Sometimes photographing at a nest or den requires specialized equipment, such as a remote-control cable release or multiple flash units. If you do not have the equipment required or you lack the knowledge needed to prevent too much stress to the subject, you should not attempt nest or den photography. There may be times when you discover an animal that is oblivious to you and gives you all the liberties you could hope for, but that is not the norm in nature. Most animals require some degree of getting used to you or need to be unaware of your presence before you can make images of them.
Your responsibility to the animals does not end once you have taken the photo. Sometimes people are careful not to disturb an animal as they approach; they crouch, crawl, and never make a sound. Problems can arise after they got their shot. Then all hell breaks loose. They may stand up, laugh, or don't care about their impact after the photo was made. This not only scares the subject, it could also put the photographer in danger if the animal feels threatened. If it took you twenty minutes to approach an animal, it should take you twenty minutes to leave it as well. Treat all your photo subjects with respect. By not interfering with your subject, you will have a great "how the animal never knew I was there" story to tell around the campfire.