Bees swarm for a purpose. Swarms are self-organizing demonstrate intelligence and emergent behavior. Swarms move in similar direction while avoiding collisions.
I have witnessed the swarming behavior of a number of agile teams. There may be no better single indicator of a teams functioning level than observing its ability to swarm.
When a team is faced with a challenge, swarming may be triggered. I have seen team members simultaneously gather to understand a problem and then quickly organize to resolve the challenge.
I have also seen teams not swarm. Consequently teams unable to swarm tend to become blocked. One set of members may believe the problem at hand belongs to someone else. Their stuff is working and the part of the system impacted is strange to them. The person or persons that attempt to solve the problem are not certain were to start. They don't know if the issue is with a piece of the system they don't understand or belongs to code they know.
Since the team does not swarm a problem (whole team takes ownership and uses it collective intelligence to resolve the issue), problems take longer to resolve. Some members are idle while others may be overwhelmed. The team become frustrated. They know something is wrong but believe someone else needs to resolve the problem.
Any team that experiences the later should take this as call to improve. Lack of collective ownership for any blocker is a sign that a team is not really a team but a loose collection of individuals. A team becomes a team once it learns to swarm by instinct. A team that swarms is a whole team, a highly functioning team!