Timing is of essence, don’t disturb a chase, a ritual, nesting behaviors…
Bad timing includes being caught in the middle of a predatory chase and distracting the event, or interrupting a mating act… Let’s dig a little on disturbing a mating. How would you feel if you had 20 pairs of eyes or lenses staring at you when you’re doing it? Unless you’re an exhibitionist, chances are that you would feel some form of discomfort. Well, we don’t know if they are uncomfortable for the same reasons than we, homo sapiens, would be. However one thing is certain: when they’re mating, they are exposed and vulnerable (to predation, competition, etc.), so let’s not add to the threats.
In all cases, limit the time you spend seeing them, don’t overstay your welcome. Think about them, think about your fellow viewers as well (be courteous and let them see too). Again when wildlife sees you and until you’re gone, wildlife remains on alert. So limit the disruption (and strictly follow the regulations if they exist as in the case of gorilla trekking events which limit a visit to an hour).
Another reason for a limited view time is that animals can become too habituated, which means this can pose a danger to themselves by not being more wary of hunters or poachers, or a danger to you and future guests as they come too close [GB15].