Answer:
Naturalistic Observation.
Step-by-step explanation:
Naturalistic Observation -
It is the method of observation in the research field , where the method used is observing the object of study in their particular natural environment , is referred to as naturalistic observation.
This helps to get a pure and proper source of knowledge for the research work , and helps to understand the subject is the best possible way.
Hence, from the given scenario of the question,
The observations done on the Koala is referred to as the Naturalistic Observation .