I am planning a purely observational research project, is IACUC review and approval still required? Yes. However, you no longer need to fill out a full IACUC Reseach Protocol. The IACUC now has a special form for observational research projects. This form is available in the IRBNet Forms LIbrary. Just remember, if you are conducting any activities that may impact the animals or their behavior (e.g. habitat alteration, offering food or nesting material choices, calling, or baiting) then your research is more than observational and you should fill out the Research Protocol.
Does observational research require State or Federal Agency permits? Maybe. It depends on the species of animal being studied. Permits are typically requried for any activities, including observational research, involving marine mammals and endangered species. The other thing that you need to consider is that a land-use permit may be required to access your study location.
Is individually identifying an animal with a temporary (hair dye or chalk marking) or permanent (ear tag or leg band) mark so you can distinguish individuals allowable as part of a "purely observational research" project? No. Capture and handling the animal to place the marker makes these projects exceed the limits of observational research. However, if the animals were marked for another IACUC approved purpose (husbandry or another research project) subsequent behavioral studies could be submitted on the Observational Research Protocol form.