Mary watches several different species of birds to discover how they feed their young in their habitat, without being intrusive. this would be an example of what type of study

Mary watches several different species of birds to discover how they feed their young in their habitat, without being intrusive. This would be an example of field research or observational research.

Observational research (or field research) is a type of research in which the observer the subject in its natural setting to make a recording of all the social behaviours displayed by the subject.

primary succession occurs in essentially lifeless areas regions in which the soil is incapable of sustaining life as a result of such factors as lava flows, newly formed sand dunes, or rocks left from a retreating glacier. secondary succession occurs