When incubating chicken eggs, one of the first signs that the hatch is close at hand is the sound of peeping and cheeping. It is an exciting moment for chicken keepers, as that first peep means that all has gone well so far and that the baby chicks should be out and about within roughly 24 hours.

But why do chicks chirp for the first time while still in the egg?

There are three reasons that seem rather likely.

Strength

The last leg of a successful hatch proceeds as follows:

1. The chick breaks the air sac at the end of the egg.
2. Its respiration rate increases.
3. The chick peeps for the first time.
4. The chick rests for an hour or two.
5. It pips the shell and eventually completes the hatch.

The initial steps of breathing and chirping provide exercise to the chick’s respiratory system. This much-needed exercise is followed by a rest period. The combined result is that the baby chick has gathered the needed strength for the somewhat lengthy task of hatching.

Thus, peeping may provide a way for the chick to strengthen its respiratory system in preparation for the hatch.

Bonding

If a chick is being hatched by a broody hen, peeping becomes doubly important. A good broody hen naturally recognizes the peeping sounds coming from her nest as belonging to one of her chicks. By the time all the eggs have hatched, she therefore already knows the individual calls of her entire brood before they ever leave the nest.

Furthermore, in response, the hen clucks to the chicks, enabling them to learn her call before hatching. Once the hatch is complete and the whole family is ready to explore the world, the hen can then easily call the chicks to her for protection or to show them where to find food.

Hatch Coordination

Another possible reason that chicks peep prior to hatching is to signal each other. When a brood of chicks is being hatched under a hen, it is important that the hatch occur within a fairly tight window of time so that some chicks aren’t dry, active, and ready to leave the nest while others are still trying to escape their eggs—after all, the hen cannot easily tend chicks in two places at once! Accordingly, it is thought that the first chick to break the air sac and peep may prompt others to do the same.