Final answer:
The nurse manager should recognize the defined behavioral norms among the staff and address the issue of criticizing and making fun of colleagues to promote a professional and supportive work environment.
Step-by-step explanation:
When assessing the staff's group dynamics, the appropriate action by the nurse manager would be to recognize that the group already has defined behavioral norms. Workplace norms often include unspoken rules about behavior, including how staff members interact with one another. Addressing issues individually may also help to maintain a positive work environment and allow for growth and change. However, it is also essential for the nurse manager to set clear expectations, which includes enforcing policies against criticizing and making fun of colleagues. Doing so will not only uphold professional standards but also promote a supportive and cohesive team.