Many animals begin to develop inside an egg or in the mother’s body, seemingly isolated from the outside world. However, embryos of some species, including humans, can sense and respond to external stimuli. A new study on seagulls revealed that bird embryos spy conversations from their parents. What information do they get? How does this affect chick development?
Talkative couples to coordinate parenting
In many animal species, parents constantly adjust the resources they invest in their offspring. This often requires active coordination of parenting tasks, so that both partners can contribute effectively to the care and education of the children.
In the seagulls of type Larus (which includes most large gulls) both sexes collaborate in caring for the young. During the incubation phase,
However, not all seagull pairs are equally communicative: while some have long conversations, others are much less so. talkative. Interestingly, more communicative couples tend to coordinate better during parenting tasks and, as a result, their children receive better care.
This raises a fascinating possibility: what embryos are capable of peek parents’ conversations from inside the egg and prepare for the kind of care they will receive.
Embryos that capture the secrets of their parents
At first glance, bird embryos appear to remain in a passive state, confined to their eggs. However, recent research indicates that they have a remarkable ability to perceive the external world through sounds, especially during later stages of development.
In the recent study conducted at the University of Vigo, we studied whether bird embryos can obtain information about the care they will receive from their parents by listening to their conversations during incubation.
To do this, we studied 44 families from gaviota patiamarilla (Larus Michaelis) In the Island of Savorain the Maritime-Terrestrial National Park of the Atlantic Islands of Galicia (Spain).
From each family, we collected two sibling eggs and exposed them to different parental communication signals in artificial incubators. One of the eggs was exposed to recordings of seagulls having long conversations, from highly communicative pairs. Instead, his brother listened to short conversations from less communicative couples.
At birth, both siblings were placed back together in a foster home. Our goal was to evaluate whether the level of parental communication, perceived from inside the egg, influenced chick development. Both brothers shared the same genetic parents and the same educational environment. Therefore, the only difference between them was in the levels of parental communication they heard during a short developmental window.
Herring gull nest (Sálvora island). Francisco Ruiz-Raya, Author provided.
Changes in the development and behavior of chicks
After analyzing the data, we found that the level of communication between parents determines the development of their children. Embryos that listened to communicative parents showed longer embryonic development than their siblings.
Furthermore, the degree of communication between parents changed the levels of DNA methylation (a biological process that regulates the expression of certain genes) and the hormonal response to stress in chicks. In vertebrates, these changes can have lifelong effects.
Parental conversations also influenced offspring behavior. Chicks that listened to recordings of their communicative parents before hatching begged for food more intensely. This behavior could allow them to obtain more food in an appropriate family context.
Surprisingly, when raised by coordinated parents, the brother who listened to talkative parents before birth showed better nutritional status and grew up faster than his brother, who felt less communication between his parents.
Seagull chicks with one of their parents (Sálvora island). Francisco Ruiz-Raya, Author provided.
Evolutionary implications
The ability of seagull embryos to listen to their parents challenges previous ideas about family communication and the role of embryos in relationships within the family.
Embryos have traditionally been seen as passive recipients of information transmitted from the mother into the egg (or uterus) through hormones and other substances. However, our findings suggest that embryos prepare for the familiar environment they will encounter by playing an active role in the environment “evolutionary conflict” between parents and children.
From the earliest stages of development, animals interact with their environment and can anticipate the conditions they will face after birth. The question is whether increased noise pollution in nature could mask or weaken the signals animals use to understand their environment.
Our results on herring gulls show that parental sounds are very important for the development of offspring and confirm that early experiences in the family environment can leave a lasting impression.
What are the evolutionary advantages of parent-offspring communication in avian species?
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Chick from a gaviota patiamarilla on the Island of Sálvora. Francisco Ruiz-Raya, Author provided.
Implications for understanding avian development
The findings from our study underscore the importance of parental communication not only in the development of offspring but also in their behavior and how they respond to environmental cues after hatching. This raises intriguing questions about the evolutionary advantages of parent-offspring communication in birds and could pave the way for further research into the mechanisms behind these effects.
Understanding how embryos are influenced by external sounds can help shed light on their developmental processes and may also inform conservation strategies for bird species that are sensitive to environmental changes. By recognizing the role of parental behavior and communication, we can better appreciate the complex interactions that shape the lives of birds even before they hatch.
As we explore these connections further, it invites a broader consideration of how communication among all animal species shapes their development and survival, potentially altering our perceptions of intelligence and adaptation in the animal kingdom.