Nature photography has become very competitive and there is always that temptation to push things a bit too far in order to obtain a striking new image. It is not only the professionals who experience competitive pressure. The standard of photography required to do well in salon exhibitions or the big photo competitions is now extremely high and so the serious amateur photographers feel this pressure as well. In the case of bird photography, photography at a nest is an area where pushing things too far can easily cause considerable damage. The obvious cause for concern in nest photography is desertion by the parents due to the photographer's presence.
Species vary greatly in their tolerance of hides and the comings and goings of a photographer.
Some species are notoriously susceptible to desertion and should be left well alone. A good example is the bateleur which in addition to being endangered is very sensitive to disturbance at the nest. I believe that under no circumstance should bateleur be photographed at the nest. On a recent visit to Kalahari Gemsbok National Park I was very disappointed to learn that an experienced photographer who certainly should have known better, drove off road to photograph at a bateleur nest. A less obvious but very real danger is predation of the chicks by other bird species or mammals such as mongooses.