Recently I was watching a documentary about penguins and how a mother penguin lost its chick. Then it went looking for it, and among a horde of penguins it was able to find its chick and take it back.

What really intrigued me is that the penguins looked exactly the same. Animals don't have as many distinctive features as we humans do, such as significally different hair color, skin color, they don't really look very different. Rather animals of the same species look very similar.

Just consider the following image: enter image description here

How can one even differentiate between all these penguin chicks? Even the parents look very similar to me.

So how can parents spot their offspring among all of these penguins that look almost identical?

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    $\begingroup$ It varies a lot from species to species. The question How do animals know who their child is? is too broad, you probably want to ask How do penguins know who their child is? instead. $\endgroup$
    – Remi.b
    Jul 23, 2017 at 14:58
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    $\begingroup$ Well the I am voting to close as the question is too broad as mechanisms vary a lot from species to species. Some would use facial recognition (e.g. sheep), others would use smell, others would not need to recognize as only their offspring stays in the neibourhood, others don't recognize their youngs, most species use some mixture of those cues, etc... $\endgroup$
    – Remi.b
    Jul 23, 2017 at 15:03
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    $\begingroup$ All the penguins appear (and would smell) similar to you. But not to the penguins. $\endgroup$
    – kmm
    Jul 23, 2017 at 15:43
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    $\begingroup$ nature gives them variance so that they recognize very easily what is important to recognize. to know the difference, many tests have been done, using sound proofing, visual screens, and they can probably recognize them by sight or sound, although sound is probably the main recourse because birds have very good ears and variable voices, and it's a 2 way thing, the parents call and the baby replies, it's not random sounds. $\endgroup$ Jul 23, 2017 at 16:09
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    $\begingroup$ @anongoodnurse You are a molecular biologist, a physician, a fan of Shakespeare, probably a parent given your activity on Parenting.SE (or maybe just a pediatrician?) and you're raising a flock of (anus smelling) goats! You sound like an interesting person to be around! $\endgroup$
    – Remi.b
    Jul 23, 2017 at 21:49

2 Answers 2


Penguins (and many birds) recognize their offspring and mate thanks to vocalizations. It's called individual vocal recognition, it's like when you recognize your friend voice among a group of chatting people.

Scientific article references for penguins:

Jouventin P., Aubin, T., Lengagne, T. 1999. Finding a parent in a king penguin colony: the acoustic system of individual recognition. Animal Behaviour 57(6):1175-1183. http://www.sciencedirect.com/science/article/pii/S0003347299910862

Aubin T., Jouventin P. and Hildebrand C. 2000. Penguins use the two–voice system to recognize each other. Proc. R. Soc. Lond. B. 267:1081–1087. http://rspb.royalsocietypublishing.org/content/267/1448/1081.short


Animals used several ways to tell who their child is, some use sounds, yes, some use spatial cues and THEN sounds to zoom in the individual they want to find, and sometimes they even need to confirm by smell!

Here is a good reference that describes this process and the different sensory cues used in a pinniped species:

Kaja Wierucka, Benjamin J. Pitcher, Robert Harcourt, Isabelle Charrier. (2018). Multimodal mother–offspring recognition: the relative importance of sensory cues in a colonial mammal. Animal Behaviour 146: 135-142 https://www.sciencedirect.com/science/article/pii/S0003347218303208

For more information specifically on what kinds of information animals can glean or transmit use of acoustic cues, this book is really informative! Coding Strategies in Vertebrate Acoustic Communication (Animal Signals and Communication 7) 2020 Editors Thierry Aubin and Nicolas Mathevon https://link.springer.com/content/pdf/10.1007/978-3-030-39200-0.pdf


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