During routine flock inspection, it is common to observe that the birds move away from the approaching person, creating a temporary corridor or open space. As the inspector passes, the birds promptly flow back into the vacated area, re‑establishing their normal distribution. This “parting and closing” behaviour is a characteristic sign of a well‑functioning, healthy broiler flock.

The phenomenon reflects several positive attributes of flock condition:

• Normal fear response: The birds maintain an appropriate flight distance, indicating that they are alert and behaviourally responsive without being excessively fearful or stressed.
• Good mobility: Birds are able to move freely and uniformly, suggesting adequate leg health, acceptable stocking density, and favourable litter conditions.
• Even distribution: The rapid reoccupation of the space demonstrates that the flock is comfortable, evenly spread, and not exhibiting clustering, crowding, or avoidance behaviour.
• Absence of clinical disease: Birds with significant illness, lameness, respiratory distress, or systemic weakness typically fail to move away or re‑enter the space promptly.

Overall, the smooth, wave‑like displacement and return of birds during inspection is a practical, low‑tech behavioural indicator of flock vitality, welfare, and environmental suitability.

In this video, a healthy 29-day-old flock is shown; the stocking density was 18.5 birds per square metre.