2022-09-15 by Khushi Goel

[Transcript] IndiaAsksWhy | Why Do Some Squirrels Bury Nuts?

[00:10] Both- “Hi Everyone”

U- I am Utsuka

J- I am Jigyasa

Both- And you are listening to IndiaAsksWhy.

U- A science podcast supported by IndiaBioScience

J: Where we do the research for you to get smarter.

U: Join us, as India becomes more curious,

Both: one question at a time!

[00:33] J: One afternoon when Utsuka was enjoying a movie about ancient animals, she observed that the squirrel in the movie was obsessed with its hazelnut. This made her wonder, why do some squirrels bury nuts in the forest? In today’s episode, Utsuka and Jigyasa find the reasons for squirrels' curious behaviors! To understand how researchers study such animal behaviors, they spoke to Dr Karthikeyan Vasudevan, a wildlife biologist who studies animals in captivity as well as in the forest.

[01:18] U: So yesterday, I watched this movie called “ice age” and I am pretty sure you have watched it too. The scenes with that squirrel are so funny, right!

[01:30] J: Yeah.. always running to save his favorite nuts.

[01:35] U: Yes, squirrels always seem to be either hiding a nut or getting a buried nut out. I wonder why squirrels do that.

[01:47] J: They are stashing up, Utsuka. Researchers have been following up on squirrels behaviors for quite some time now.

[01:54] U: and.. What have they found?

[01:57] J: Squirrels found in cold countries like America and Canada like to stock up all nuts for the future. They are always prepared to face the harsh winters when there is nearly no food available in the forest.

[02:13] U: I have so many questions, Jigyasa. How do squirrels know where to store and what to store and most of all, who teaches them that they need to store their food. And…

J: Hold on! Hold on! Ask them one by one. Animal behavior researchers followed squirrels for several months trying to find answers for some questions like yours. After analyzing all their data, they have learnt so many things about squirrels.

U: They did?

J: So you were asking, who teaches the squirrels to do all this? Squirrels are born with this ability to hide specific foods. The way we buy different groceries and stock up in our for every week, squirrels do so for a different three nuts. This is called innate behavior. Scientists compared squirrels that were born in the lab to squirrels that were born in the forest. They gave them specific nuts to see what the both sets of squirrels do with them and not so surprisingly, both the sets of squirrels, buried the nuts.

[03:21] U: So nobody teaches them how to bury the nuts then. They just know it. So fascinating, Jigyasa. But how do squirrels remember where they have buried their nuts? And do they sometimes forget where they stored food just like us?

[03:40] J: Good question, Utsuka. Studies show that some squirrel species recover 95% of their nuts they buried. While the others are not so good and only recover about 25% of the nuts they buried. But in general, squirrels have an amazing sense of the space they live in. They remember the location of the place by its color and use their sense of smell to guide them back to it. That’s how they retrieve their nuts. To keep their food even more safe from their competitors, squirrels also tend to move the nuts from one place to the other.

[04:25] U: Woah… squirrels are super smart. So my next question, how do squirrels decide where to store their nuts?

[04:34] J: Oh! you are going to love this answer. Squirrels are curious and vigilant. They look around, explore and keep track of their predators. Some squirrels like to put all their nuts in one place in a forest. Like a big storage cupboard in our houses. But others like to spread their food all around the place they live in. It is as if you pick one of your favorite chips and you store one pack in your study table drawer, another maybe in your bathroom and one under your sofa. This way, your sibling can never get all your packets at once.

[05:15] U: haha.. Yes. So if I kept all my chocolates together all in one place, they would all vanish together too.

[05:23] J: Exactly. So when a squirrel is being watched by another squirrel, that is a competitor, it changes its behavior. Sometimes it even fakes burying a nut to trick its competitor away.

[05:37] U: wohh! Such tiny animals, but such magnificent brains! I have one more question.

[05:45] J: You are just as curious as squirrel, Utsuka.

[05:50] U: So how does the squirrel decide which nut to bury and which nut to eat right away?

[05:55] J: So researchers found that squirrels inspect the nut to make this decision. If you ever look at a squirrel carefully, they keep moving around with the nuts in their hand. This way they can check if there are any holes in the nut or there are any dents or spots, which may sort of indicate that there is damage to the nut. So if the squirrel see such damage, they think to themselves. “Hmm… this doesn’t look so good. It won’t stay very long. I should probably eat this now.” and when the nut is free of all these damages, it thinks “oh! What a perfect looking nut. It can probably stay stored for a long time. So I’ll store it for later”

[06:40] U: Super interesting. Squirrels are just like us. They inspect the food and make clever decisions to survive in the wild forest. But I have seen so many squirrels in India but none of them bury the nuts in the way that I have seen in the movies. Why is that?

[07:03] J: Yes, squirrel species that bury nuts are only found in cold countries where…

U: It is difficult for them to find food in winters.

J: Exactly. In India, therefore food sources never get out of hand. Even in the winters.

U: So… what would happen if I moved the squirrel from the cold country to India? Like forever. Would the future generations of that squirrel forget to bury food?

J: Hmm… you’ve got a very interesting point. If we take an animal out of its natural habitat, would it forget its innate behavior?

U: Yes, that’s what I wanted to ask.

J: Let’s ask Dr Kartikeyan.

[07:49] J: And now… it is time to ask a scientist.

[07:54] U: Now we have Dr Kartikeyan Vasudevan who is a wildlife biologist from CCMB, Center for Cellular and Molecular Biology. He studies animals, both in the forest and in a zoo. He learns about endangered animals and helps to save them. So Jigyasa, Why don’t we go ahead and ask our question?

J: So Dr Vasudevan, in the first segment of this episode we learnt that squirrels bury nuts and that sort of brings us to asking, How do animals learn these things? Who teaches the animals to do these things?

V: Yeah, that’s always a very intriguing question for a person who observes them. So if we relate these behaviors to survival, how they can keep their body conditioned, intact, and reproduce and raise their offspring. That's a huge pressure on any wild animal. Yeah, that’s where I would describe these behaviors, explain these behaviors to start with.

U: So the environment they live in, sort of determines what kind of behaviors they might have?

V: Yes, it is the environment and also the conditions that are there. There are biotic and abiotic factors. Abiotic factors are what you call temperature, humidity, precipitation. Then there are biotic factors, that is resource availability. Every animal requires resources, either plants or animals to feed upon. And then another biotic constraint is predators. The third thing is finding mates. So, all these things come into the picture and play a role in deciding what behavior we would perform.

[09:39] U: So, as you already pointed out there is so much variability that can happen in their environment. But yet they have some behaviors which are constant no matter what. Right? How do they get such behaviors? For example, squirrels bury nuts no matter what, right? And why do certain animals have such specific behaviors?

[09:59] V: See there are some, which are called ‘innate or instinct behaviors’. We also have such instinctual behaviors like, for example, an infant or a human child having the ability to clutch anything, right? Now, if the new born child doesn’t grip the mother, doesn’t hold the mother and cling on the mother for warmth and for nutrition, it is most likely to die. See, the innate behaviors are like you know windows that open and close during the development of the organism. So for example, if a chick, the birds hatch, the chick doesn’t beg for food, right? It doesn’t get food. Now it will beg for food at a certain stage in its life. It will not beg for food after a few weeks because it will start to forage. Okay? So that begging behavior will be open as soon as it hatches. The moment it comes out of the egg, it will beg for food. So this happens at a certain time network and then it stops.

[10:59] J: When we imagine scientists studying animal behavior, we imagine a laboratory where an animal is kept in a sort of a cage and you study its behavior. But we can also imagine that this might not be their natural behavior because they are taken out from their natural setting. So we are curious to know, how do you study animal behavior in your setting, in your lab?

[11:22] V: Yeah, so while the animals show behaviors which are surely native to their conditions but when they are moved into captivity, some behaviors change. There are some cardinal rules of making observations that don't become a factor in modifying the behavior. So you have to habituate the animal, you become like a tree in landscape and like a branch of some plant and just be there; and just observe and not speak and not do anything that disturbs the animal. And with time the animal begins to trust you. You know, they develop a perception that this person who comes with the same binoculars and a notepad and just does some scribbling in the notebook is not going to harm me. And they just go about doing their own stuff. So yeah, easily a behavioral study will take about 300 such full days of observation after the habituation period.

[12:19] U: So, because you have studied animals in the wild as well and you study animals in captivity also. Have you ever observed peculiar differences between their behaviors from the wild compared to when they are in captivity?

[12:31] V: Yeah, very much. See, many things change when they are in captivity. First thing to change is confinement in space. The space is reduced dramatically because there are walls all around. Second thing, there are no predators, it’s very safe. Third thing is that the food changes completely. Right? In the wild, there is so much stimulation, sensory stimulations, noises, sounds, smells; things are unpredictable, it rains, then it is dry, then you have to search for water. So the lack of sensory... Sensory deprivation that they undergo and the restriction of space that is made to happen when they are brought into the zoo, forces them to perform abnormal behaviors. And these are redirected behaviors like in the case of primates, they groom each other. And for them grooming is like us sending a whatsapp message, you know, it’s a connect for the primates. They are checking out, are you okay? Or all those things. So when they are doing the grooming, if that is deprived they start doing things harmful to themselves like pulling out hairs from their own body, or aggressively grooming themselves, and performing behavioral switches which are totally unnatural.

[12:50] J: If we get a wild animal and have it in captivity for many years, like the animal is bred in captivity for many years. Is it possible that at a certain stage they don’t have those behaviors enough that they can go back to the wild?

[14:06] V: It’s a wonderful question. Now if we have to do that, as I told you previously, those abnormal behaviors might be reduced in the captive prone generations. But we should ensure that the sensory stimulus to natural behavior still continues to persist. They still should be interested in foraging, for example. Right? So that is a very important factor we have to take into consideration when we are even thinking of breeding them, increasing their numbers. What is the purpose? What are we trying to achieve? If the goal is to finally reintroduce them, these factors need to be brought in at that stage itself.

[14:52] J: On that note, I would like to ask you if there is a younger generation who also enjoy watching animals, learning their behavior. And may want to at some point pursue such a career like yours. What’s that advice that you’d give to our listeners in that perspective?

[15:07] V: For students, don’t feel guilty of gazing. If you are a gazer, watch through the window when a class is going on, it’s not wrong. It’s very important and you should be able to justify it based on what you have listened to just now that it is important to watch a sparrow or a crow or a butterfly just through the window. And just be curious enough to follow it periodically and there’s nothing that makes it wasteful to make that observation. There is nothing wasteful about it both for oneself and for every other reason that might help you in future. So I think just be unashamed and say, I love to watch and just observe and just be curious and observe.

[15:58] J: So Utsuka, what did we learn today?

U: Squirrels are born with the ability to bury the nut. This kind of behavior is called innate behavior. Just like you and me squirrels are curious and they try to be prepared for the harsh climate. Some squirrel species have excellent memory and complex hiding methods that help them win over their competitors.

J: And Dr. Karthikeyan explained to us how they compare observations of animal behaviors in the wild and captivity! He advises that we shouldn’t shy away from gazing out of the window once in a while!

J: But listeners, what we know about animal’s innate behaviors might change as we get more evidence over time.

U: Who knows, one of our listeners might study wild animals in the future to find out something that we never knew before!

[17:10] U: So that’s it for today.

J: If you want to know more about today’s scientist, we have linked his profile in the Show Notes!

U: If you have any questions that you want us to explore, shoot them away to Indiaakswhy@gmail.com

J: If you'd like to directly talk to us directly, then join the fun, join the fun on our Telegram Group. Link in the show notes.

U: For updates on IndiaAsksWhy, follow @IndiaAsksWhy on Twitter, and @India_AsksWhy on Instagram.

J: Shweata N. Hegde and Ruchi Manglunia are the hosts for the podcast.

U: Indulekha MS edited this episode.

J: and Khushi Goel transcribed it.

U: We are funded by IndiaBioscience’s second outreach grant.