For decades, commercial incubation has been optimised around well-established physical variables: temperature, relative humidity, ventilation, CO2 concentration, and egg handling, among others. Yet, despite birds being among the most vocal animals, their vocalisations have rarely been used as indicators of day-old chick quality. During the incubation period, chicks respond to external sound stimuli, coordinating their development, modulating their behaviour, and influencing their subsequent viability. Understanding what happens “from egg to first cheep” means learning to listen to the birds from within the hatchers.
The invisible symphony inside the hatcher
Although the hatcher appears from the outside to be a closed system, a great deal of biological activity is taking place inside. Through the eggshell, embryos perceive vibrations and sounds from relatively early stages of development. In the final phase of incubation, once the respiratory and nervous systems are sufficiently mature, acoustic communication intensifies.
Under natural conditions, the brooding hen stimulates embryos through her vocalisations, accelerating or synchronising physiological processes that encourage chicks to hatch within a narrow time window. This mechanism has clear adaptive value: a synchronised hatch reduces the risk of predation and facilitates the simultaneous departure from the nest.
In commercial hatchers, the maternal figure is absent, but embryonic communication is not. The embryos become both emitters and receivers of sound signals, creating a network of interactions that directly influences hatch dynamics.
Detection of Internal Pipping
Several scientific studies demonstrate the early detection of internal pipping. This event marks the moment at which the embryo pierces the inner membrane of the egg and begins pulmonary respiration.
Using piezoelectric microphones and high-sensitivity acoustic sensors, it is possible to identify this biological milestone with an accuracy of approximately ±3 hours.
Knowing the actual, biological — not theoretical — moment of internal pipping makes it possible to dynamically adjust temperature, ventilation, and CO2 profiles. If pipping occurs earlier than expected, a timely reduction in temperature can prevent embryonic overheating, a frequent and costly problem that is often only detected once chicks are already showing signs of panting and stress.
The first cheep
Once the chick breaks through the inner membrane of the egg, it begins to pip, cut, and emerge from the shell. During this process, the birds start to vocalise.
Numerous studies in experimental laboratories have demonstrated that these acoustic stimuli serve a synchronisation function. Embryos that “hear” others initiating the hatching process adjust their own developmental rhythm, bringing forward the moment of hatch.
From a production perspective, this synchronisation is critical. A wide hatch window generates significant inequalities: the first chicks to hatch spend additional hours in the hatchers, increasing the risk of dehydration, while the last may emerge incompletely.
Currently, the most widely used method in hatcheries to obtain a real and accurate picture of the hatch window is the visual count of a limited number of randomly selected trays within the hatcher.
Although routine, this procedure has several limitations:
1) it depends on staff availability,
2) it introduces an inevitable degree of subjectivity, and
3) it provides only an approximate estimate of the total number of chicks hatched.
Furthermore, this approach does not allow precise identification of the moment the first hatch begins, as checks are carried out at discrete intervals rather than continuously.
Automated acoustic detection of vocalisations within the hatcher offers an innovative and far more precise alternative. Each chick, upon hatching, begins to emit characteristic sounds, and the analysis of these acoustic patterns enables the exact moment of the first hatch to be recorded continuously and without human intervention. This type of monitoring provides a detailed temporal curve of vocal activity that reflects the progress of hatching and the complete dynamics of the hatch window in real time.
Achieving a narrower hatch window with less temporal dispersion translates directly into greater flock uniformity and higher-quality chicks. A synchronised hatch significantly reduces birth-weight variation, decreases dehydration in early-hatching chicks, and prevents the emergence of weak birds, thereby improving subsequent performance on farms.
The importance of monitoring chick despatch
Before chicks can be delivered to the customer, the birds are dried, sexed, vaccinated, and graded to remove unfit individuals, and are finally counted and packed into transport boxes. This industrial process subjects the birds to stress that affects the animals. In the despatch room, the birds stabilise their body temperature and recover after hatching while transport logistics are organised for collection. Monitoring and controlling conditions in the despatch room is key to ensuring the animals are in the best possible condition prior to transport and to avoiding stress.
Under optimal conditions, chicks emit a rhythmic cheeping associated with normal activity. However, excessive density and the resulting rise in temperature lead to panting, accompanied by a marked reduction in vocalisations, while cold spots caused by poor air distribution produce high-pitched distress calls.
Acoustic monitoring of birds in the sexing and despatch rooms makes it possible to detect vocalisation patterns and optimise management, thereby maximising flock welfare.
Bioacoustics allows us to listen non-stop to everything the chicks “tell” us from the moment they hatch until they are loaded onto the truck bound for the farms
From embryonic clicks to the first cheeps, vocalisations provide real-time information on the physiological state of both the embryo and the newly hatched chick. Learning to listen in the hatch room and in the despatch room not only improves hatch synchronisation and chick quality, but also opens the door to more precise, adaptable incubation that is better aligned with the bird’s natural biology.
In a context of high production demands and growing focus on animal welfare, the future of incubation cannot rely solely on better temperature or humidity sensors; it must also measure and know how to interpret the indicators generated by the birds themselves, such as their vocalisations. Paying attention to what embryos and chicks communicate is a fundamental step towards incubation systems that are more efficient, more responsive, and truly animal-centred.
Gerard Ginovart, Tesa Panisello and Silvia Riva
www.CEALVET.com
Benefits of bioacoustics in poultry farming:
-. Article 1: Why the chick’s voice matters: scientific foundations of avian bioacoustics
-. Article 2: From egg to first cheep: what chick sounds tell us in the Hatchery.
-. Article 3: Thermoregulation, hunger and stress: what chick “distress calls” reveal