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Before they even hatch, Yellow Legged Gull chicks seem to be communication to their nest mates. Amy dives into the how and why.
Show Notes:
Science Alert - Michelle Starr
Unhatched bird embryos can not only hear the warning calls of adult birds - they can communicate that information to their unhatched brothers and sisters sharing the same nest, remaining safely tucked away in their shells until it is safe to hatch.
https://www.nature.com/articles/s41559-019-0929-8
Authors Jose C Noguera & Alberto Velando
Ecology and Animal Biology Department, Spain
Episode Transcripts:
Welcome to Brain Junk. I'm Trace Kerr and I'm Amy Barton and this is a Brain Storm.
AB: I'm pretty excited about this one because it's how baby birds communicate before hatching. Isn't that great? Cause we've talked a little bit about how newborns learn when they sleep and I love that.
TK: How a new thing learns a thing.
AB: Yeah. So this is about that scientists from, I have to translate this from the University of Vigo in Spain. That's not how it's written here, but that's what it is in America. It's the Departamento de Ecología y Biología Animal, Universidad de Vigo, Vigo, Spain. I took French. Everybody, I can't tell you. The authors of this study study are Jose, Nick Guerra and Alberto Valando. They studied unhatched yellow legged goals and found that the unhatched baby bird embryos and not only heard warning calls of adults, they also can communicate that information to unhatched brothers and sisters sharing the same nest. So they were curious what, how does that happen? What's the mechanism? The scientists did a study, they're like, how does this work? And
TK: Oh, is this another scientist doing horrible things to creatures to do a study?
AB: Not horrible. No. There's moments where it's like, ahhhh, but nobody dies and no birds die.
TK: Okay.
AB: They took lots of these little unhatched yellow legged goals and they put them in little groups of three in incubators and so it looks like ice cube trays in the illustration. Oh, there's a row of three. There's like seven rows of three. They had a control group and a study group and what they would do is one of the eggs would stay in the incubator all the time. It's two neighbors would be pulled out and in the control group they would just be pulled out and put in a quiet box and they wouldn't hear any auditory stimulus and then they go back in the study group, the two eggs and it was always the same two eggs, the same two eggs would be pulled out and they'd be put into a soundproof space and they would be played. The sound of the adult predator alarm calls would be applied, so mama bird freaking out because a predator is coming would be played and then they would return the eggs to the nest. What they found from that is that the test group eggs tended to vibrate more in the incubator. So there would be motion from those eggs but not from the control group. And when the experimental clutches hatched, even the naive egg, the one that wasn't exposed, they all took longer to hatch than the control group control group would hatch kind of on a normal schedule. The ones in the study group hatch later and they emerged from the shells in a much more cautious way. And they even had physical changes. They had shorter Tarsus. So that's just their leg. And they had a higher stress hormone level.
TK: They were more conservative, little birds coming out came out later on.
AB: They were more watchful and aware.
TK: So they probably got eaten less.
AB: As a result, those birds have a higher stress level, but they also probably have a better survival level. Right. Well and they would also be older when they were coming out of the egg. So the development would be faster.
TK: And so what you're saying is is that that third egg that never went, never heard also hatched later.
AB: Yup. And it also exhibited the same level of caution when it emerged from its shell. Like we might be attacked on this first day of our lives.
TK: Um, so it did exactly the same thing as the other two. So it was as though it had been exposed to that stimulus too, even though it's just in an incubator in a lab. Huh.
AB: It seems likely that those unhatched chicks can communicate danger to their nest mates just by vibration.
TK: Wow. I wonder. Um, okay, so the scientist in me says you're taking groups out and you're playing the bird alarm call. Were there also ones that were taken out and played something else that wasn't the alarm? Do you know what I'm saying?
AB: Oh yeah. You know, cause the control group gets silence.
TK: Okay. And your other ones get the alarm call. What if you get happy chill mama sounds.
AB: Yeah. You know what if there are those, because is it that come out swagger and like, Hey bro, is it the, is it the, is it the loudness of the sound? Is it the quality of the sound as it sounded? I mean, so there's a lot of like questions, but the fact that that noise was affecting them in some ways. Very fascinating, huh?
AB: Yeah. So that's my Brain Storm.
TK: I am filled with wonder.
AB: Oh, good.
TK: Yeah. Well, we are on Facebook and Instagram as BrainJunPodcast, and you can find us on Twitter, (not hidden in an egg) as @MyBrainJunk. Amy and I will catch you next time when we share more of everything you never knew you wanted to know. And I guarantee you will not be bored.
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