The Little Mouse That Matters: Pacific Pocket Mouse

00:00:04
Speaker 1: Hi, I'm Rick Schwartz and I'm Marco went.

00:00:07
Speaker 2: Welcome to Amazing Wildlife, where we explore unique stories of wildlife from around the world and uncover fascinating animal facts. This podcast is a production of iHeartRadio and San Diego Zoo Wildlife Alliance, in international nonprofit conservation organization which oversees the San Diego Zoo and Safari Park. Last episode, we mentioned that we were going to spend some more time this season exploring the conservation hubs of the San Diego Zoo Wildlife Alliance and as a reminder, a conservation hub represents a region of focus for our conservation efforts. These efforts include working with other zoos and conservation organizations, sharing knowledge with international communities, and building collaborative partnerships that have a lasting impact on the survival and well being of all life on Earth.

00:00:51
Speaker 3: And with our hubs being all over the world, from the African forest to the savannahs, or the Pacific Islands to Amazonia, I love that we also have one right here in our own backyard, the south West Hub.

00:01:05
Speaker 1: Ah.

00:01:06
Speaker 2: Yes to go to the Southwest Hub. Let's see that hub includes species like the burrowing owl, the desert tortoise and the mountain yellow legged frog, just to name a few.

00:01:14
Speaker 3: Yeah, you know, it's funny now that you listen like that, it reminds me of all the different types of ecosystems in one hub. In the Southwest Hub, we have the pocket mice that live next to the ocean, the burrowing owls in the grasslands and desert tortoises in the desert, and the high altitude mountain yellow leaked frogs.

00:01:35
Speaker 1: Oh.

00:01:35
Speaker 3: My favorite conservation story the California condor.

00:01:39
Speaker 2: You can't forget the condo.

00:01:40
Speaker 3: You can't, especially online. Being the bird guy, gotta highlight that one. And it's great because they cover all different ecosystems there.

00:01:47
Speaker 2: Yeah, you bring up a good point. Conservational hubs, like any region or ecosystem, can have a lot of similar or different things in them.

00:01:54
Speaker 1: Exactly.

00:01:54
Speaker 3: I mean, for now, I want to stick with the Southwest Hub just for a little minute, or honestly for the whole episode.

00:02:01
Speaker 1: Okay, thank you.

00:02:02
Speaker 3: In the last episode, we learned that the environment changes how some lions live, like being solitary or living alone instead of being a pride. And we also learned that the same environment made for the male lines without Manes.

00:02:16
Speaker 2: Yeah, it's true, we did find that out, But what does that have to do exactly with the Southwest sub Well.

00:02:21
Speaker 3: The species I'm thinking of hasn't necessarily changed due to the environment it lives in, but the environment it lives in would change quite a bit without the species.

00:02:32
Speaker 2: Hmmm. All right, so now you have me interested. Which species are you thinking of?

00:02:36
Speaker 3: Well, you know it would be a little too easy to tell you, buddy, So I want to see if you and the listeners can figure out what species we're going to be talking about if I give you just a little bit of clues.

00:02:46
Speaker 2: Oh, well, this to be easy. I know a lot about animals, so I'm always up for a game. Give me those clues, buddy.

00:02:50
Speaker 1: All right, all right, here we go. Okay, here are the clues.

00:02:54
Speaker 3: Three pennies graniv ore, toper and soil drology.

00:03:00
Speaker 2: Wait wait, wait, wait wait wait, three pennies torper or toper in soil hydrology. I know what torpor is, but I'm not sure about granted or honestly, and how exactly does three pennies fit into anything in conservation?

00:03:17
Speaker 3: I know, I know it sounds a little wild, but maybe one more clue will help Guinness Book of World Records.

00:03:25
Speaker 2: Seriously, Marco, that's supposed to help.

00:03:27
Speaker 1: Okay, okaygo.

00:03:29
Speaker 3: I think it will all make sense soon enough when I tell you I had a really interesting discussion with one of our behavior researchers.

00:03:37
Speaker 2: Oh okay, well, I'll be listening carefully for those hints, especially three pennies in Guinness Book a World Record, because I still don't see how that fits.

00:03:45
Speaker 1: But okay, let's do this. I feel I feel it. Trust me, it will all come together for you.

00:03:50
Speaker 4: I am Alison Gregor, and I am a researcher with the San Diego Zoo Wildlife Alliance. I'm very fortunate that I get to research all sorts of things. My background is in animal behavior and animal learning, which is common across many species. I have the pleasure right now of working with the Pacific pocket mouse team and then also with the Hawaiian bird team as well, so across several of our different hubs that.

00:04:14
Speaker 5: We have here.

00:04:15
Speaker 4: But yeah, it means that primarily I get to help prepare the animals in our care for life in the wild.

00:04:21
Speaker 2: Aha, she said, Pacific pocket mouse and Hawaiian birds and Marco, because you said you want to talk about the south West Hub. I'm pretty sure this is going to be about the Pacific pocket mouse.

00:04:32
Speaker 1: Very clever, very clever. I need to catch that now. I know you know a thing or.

00:04:37
Speaker 3: Two about them, But Allison, can you tell us, for anyone listening today that might not be familiar with them, what is a Pacific pocket mouse?

00:04:45
Speaker 5: That's a great question.

00:04:46
Speaker 4: Most people hear the word mouse and think they know what they are working with, but actually, the Pacific pocket mouse is a unique species that's only found in a small stretch of coast along southern California. They are dry adapted species and part of the Heteromyad family, and that means that they have little fur lined cheek pouches that they use to store and move around seeds. And the reason why they have those is that because they need to conserve water. If they were to carry their seeds in their mouth, they would lose the water from their saliva when they carry the seeds around.

00:05:21
Speaker 5: So they've evolved.

00:05:22
Speaker 4: They're so dry adaptive they have even involved these little pouches to help carry their seeds around.

00:05:27
Speaker 2: Huh. Well, that's a cool adaptation. But that makes me wonder are there any other mice that have an adaptation like that or is it just a Pacific pocket mouse?

00:05:36
Speaker 4: So any rodents in the Heteromyad family, and that involves kangaroo rats and a variety of different pocket mice. But we're lucky here that in our backyard in southern California, we have the Pacific pocket mouse, and they are found within four to six kilometers of the coastline. They specialize in these fine grain sandy soils that are found in coastal sage scrub habitat and along coastal.

00:05:58
Speaker 5: Dunes, and they here.

00:06:00
Speaker 4: They are unique to our area and are found nowhere else.

00:06:05
Speaker 3: Allison, speaking of unique to our area, I know that the Pacific pocket mouse is also unique because they are considered to be one of the smallest mice species here in North America.

00:06:14
Speaker 1: But how big are they?

00:06:16
Speaker 4: To put it in terms that people might understand it, they're the weight of about three pennies.

00:06:20
Speaker 2: Ah, there, it is three pennies. That was one of your hints, Marco.

00:06:25
Speaker 1: Yep, nice cats, Reick.

00:06:26
Speaker 3: And for those of you listening, you can feel just how little these mice.

00:06:30
Speaker 1: Way.

00:06:30
Speaker 3: All you gotta do is go get three pennies, hold them in your hand.

00:06:33
Speaker 2: Doesn't weigh much Okay, hold on a second, MARKO, I'm gonna google this. I like numbers. Let's see how much just three pennies weigh?

00:06:40
Speaker 1: Oh yeah, okay, what'd you find out?

00:06:42
Speaker 2: Hold on here, this is all right. Let's see US Treasury website says a penny weighs two point five grams, So let's see times three. That's about seven point five grams.

00:06:52
Speaker 1: That is so teem, Oh my gosh, so small.

00:06:55
Speaker 3: And oh remind us Allison, where exactly do these little teeny tiny mice live?

00:07:00
Speaker 4: From the coast up to four to six kilometers depending on where those soils stop. So they need a very special type of soil because they dig burrows, and when they're not out foraging or trying to find mates, they spend their time down in their burrows, especially over wintertime when there is much less food availability for them. They specialize on native seeds from forbes and grasses. But in the winter times, when you know, in California you don't have all of the seeds all year round. We have a seasonal climate here, and so they spend longer periods underground in their burrows in what we call torpor, which is like hibernation. Light They don't go down into a den for months at a time, but they will slow their metabolic rate and be down for several days, maybe come up, down for several days, come back up. So they go through a really interesting physiological change during the wintertime which helps them be adapted to the landscape that we have here.

00:07:57
Speaker 2: Aha swarper a state of inactivity that is like short bouts of many hibernation. That was another one of your clues.

00:08:03
Speaker 1: M Well done, buddy, Alison.

00:08:06
Speaker 3: Earlier when I was giving Rick hints about this episode, he said he was familiar with what toper is, but I know some of our listeners may not be as familiar with it. Can you explain what the mice do during toper?

00:08:18
Speaker 4: So during that torpor period when they slow their metabolic rate, they also lower their internal body temperature as well, and we don't actually know that much about what those patterns look like in the wild. That's some of the research that we're doing here with our conservation breeding population to try and understand what is natural torpor and how is that impacted by some of human activities. For instance, if there's sound that might wake them up from their torpor and then they have to come out of their sleepy state and go back in rather than being able to stay asleep. So within our the population that we care for here, one of our big goals is to try and understand as much about them as we can so that we can better support them both in our conservation efforts and in the wild And so that is one element of what we're studying.

00:09:04
Speaker 2: Wow, that is really interesting because we often think of how our use of land as humans takes away space for wildlife. But the understanding that the sounds and noises we make can also impact neighboring wild spaces, like waking an animal out of torpor is something we rarely think of.

00:09:21
Speaker 3: Yeah, right, it's super interesting, isn't it. And with the Pacific pocket mouse living only in coastal areas and areas that humans like to build their homes. Also, what does their current range to look like versus what it looked like in the past.

00:09:34
Speaker 4: So previously they had had that sweet spot of the right types of soils and native vegetations across their entire native range. So that was from about El Segundo Dunes in Los Angeles County down to the border with Mexico, and they had that whole area that's also where we like to build our homes. We like to be able to have views of the coast, and that's where there's been a lot of development, so there are very few patches of habitat left for them. We work with many partners to try and find the remnants of habitat that are left and restore actively restore them where possible so that we can start to put together.

00:10:14
Speaker 5: The remaining population.

00:10:15
Speaker 4: So actually, for twenty years they were undiscovered in the wild, thought to be completely extinct, and then three tiny remnant populations were found, so the three little postage stamps along their whole previous native range, and so once they were rediscovered, that's when we with the many other partners, started the planning process of bringing them back and trying to figure out where can we put populations of pocket mice once we were able to breed them, and there was a lot to learn in order to be able to breed them in human care and figure out how to set them up for life in the wild. So we're still along that journey. It's a long journey, but we now have a fourth population that we've been reintroducing to in the Laguna Coast Wilderness Park.

00:11:00
Speaker 3: That is most excellent news to go from three small populations, so now having a fourth population out there is most definitely a positive trend.

00:11:09
Speaker 2: Yeah right, that is a trend.

00:11:11
Speaker 1: I hope we continue to see Allison.

00:11:13
Speaker 3: I know Rick likes being outdoors as much as I do, and with both of us living here in southern California, what are the chances of ever seeing a Pacific pocket mouse in the wild.

00:11:22
Speaker 4: The one place that's open to the public where there are a Pacific pocket mice is Dana Point. There's a small nature reserve on Data Point right along the coast there that does actually have pocket mice. You're not likely to see them though, because they're nocturnal, and I believe the reserve is closed at night, but you will be in their mist and you will see a habitat that is impacted by their presence as well. Even if you don't see them there, they are having an effect.

00:11:48
Speaker 5: The burrows that they create.

00:11:50
Speaker 4: Increase the soil hydrology, so help plants there get water flow. They also the seeds that they move around, they cache them. That means they hide them for later, both in their home burrow and scattered throughout their territory.

00:12:04
Speaker 2: Wait, wait, wait wait, I do want to ask more about the seed caching you mentioned, but there was another one of Marco's hints in there, soil hydrology. Alison, you mentioned of their burrows help with soil hydrology. What exactly is.

00:12:15
Speaker 4: That soil hydrology? So that's the movement of water under the soil. If you have burrows for the water to go into, then that brings water further down than it would be if there weren't any holes on the surface.

00:12:26
Speaker 2: Ah okay, well, I appreciate you clarifying that. I don't think soil hydrology is really something we think about too often, but it is interesting how these little mouse's burrows play such an important role in how water can get into the soil more effectively and thus allowing the plants to thrive.

00:12:41
Speaker 1: Yeah, exactly.

00:12:42
Speaker 3: I mean it makes me wonder what other little things that Pacific pock mouse does that are also important for the ecosystem, and what other things might be challenging for them in the wild. Hey, Allison, we know as human populations grow, land development can impact different species in different ways, like you mentioned looking into noise pollution interfering with toper. What other challenges are the Pacific pocket mice facing.

00:13:05
Speaker 4: Yeah, that's a very important point. So in addition to human development, there's been an incredible spread of non native grasses throughout southern California. I mean, it's happened in many places in the US and worldwide. But it changes the habitat to the point where they don't have the bare ground that they need to signal to each other. They use their own scent to plot out their territories and communicate that way, and they don't have the ground.

00:13:29
Speaker 5: That they need for their burrows.

00:13:31
Speaker 4: The non native grasses also hold a lot of fuel for fires. So we know that fires are a natural part of the ecosystem here, but because of human impacts, they are occurring with a lot more frequency and much higher intensity. So all of that fuel that's held by the non native grasses burns hotter, which means that it decimates the ecosystem in a way that would have maybe been a slow, low fire going through every few decades now happens at a much faster timeframe and much more tensely, So that's a major threat to them. Also, close by to their habitats, they are affected by light pollution, and this has been shown in many other small mammals, any nocturnal animal, light pollution is likely to play a disruptive role, and we don't yet know the effect of sound. That's one of the things that we are considering. But we think that they could be vulnerable during their periods of torpor, because that's when they are trying to sleep.

00:14:26
Speaker 2: Now, Allison, you mentioned that the invasive plants were part of the problem. These are plants that aren't native to the ecosystem but start growing there, impacting the Pacific pocket mouse as food sources, and prior to that you had mentioned they stash their seeds for later. Do they only eat seeds or do they eat the other parts of the plants as well.

00:14:45
Speaker 4: The Pacific pocket mouse is a granovore. They feed primarily on seeds and that has determined a lot of their whole biology and their way of being as well.

00:14:55
Speaker 5: So they collect seeds.

00:14:57
Speaker 4: To be able to have them at times when there aren't se eats available. They hide seeds in the landscape and in this way, by being a gran of ore, they help spread the seeds around as well, which can have a benefit to the plants too.

00:15:12
Speaker 1: Hey, Rick, did you catch that one? Yep?

00:15:14
Speaker 2: Granivre? Another one of your hints from earlier, just going to check the list here. Let's see three pennies torpor soil hydrology or understanding how water gets into the soil, and now granivre an animal that eats seeds for its primary food source.

00:15:29
Speaker 4: They eat nothing else and they don't even take standing water.

00:15:33
Speaker 2: So where do they get their water from?

00:15:36
Speaker 5: They get their water from their seeds.

00:15:39
Speaker 1: Gay in descente how interesting.

00:15:41
Speaker 5: So that's how dry adapted they are.

00:15:44
Speaker 4: It is likely that they might on occasion take a little bit of vegetation, or they might have an insect here and there, but they are primarily granivores, which means that they are specialized and adapted to eat seeds, both physiologically that's why they have furlined seed pouches so they can fill them with seeds and move them around, but also likely cognitively as well, so they learn where and how to hide their seeds so that they have them to be able to survive the winter. So they are absolutely tied to seeds.

00:16:16
Speaker 3: I love that they hide their seeds for later, like some bird.

00:16:19
Speaker 1: Species that I love.

00:16:20
Speaker 2: It's right, Marco, and I want to ask you, Allison, where do they hide their seeds?

00:16:25
Speaker 4: They create little burrows and they hide their caches of seeds, and by doing so that helps spread seeds native seeds. They don't necessarily find them all, so to speak. And so they are helping the ecosystem continue. And they might seem like a very small player, but they're an important part of that puzzle.

00:16:41
Speaker 2: Okay, I hate to admit it, but I can relate to forgetting about food that I have stashed. I mean, in my case, food that I've stashed in the back of the fridge.

00:16:48
Speaker 1: But yeah, totally.

00:16:50
Speaker 3: But the food stash you forget about turns moldy and stinky. Right at least when the Pacific pocket most or gets its food stash, the forgotten sash of seeds just grows into more plants and helps the ecosystem.

00:17:02
Speaker 2: Yeah, you're not wrong there. My leftovers are not seeds helping the ecosystem.

00:17:06
Speaker 1: Yeah, I bet.

00:17:06
Speaker 3: I mean, I know, my leftover at the metallists are definitely not helping plants to grow.

00:17:10
Speaker 1: But okay, okay, we're getting a little side tracked here.

00:17:12
Speaker 3: Obviously, the Pacific pocket mouse is an important part of the ecosystem. They live in Allison and the whole team working on the Pacific pocket mouse conservation are doing great work to build the population back up. Is this a species that lives for a long time.

00:17:27
Speaker 4: So in the wild, the Pacific pocket mouse do not live very long at all, two to three years maximum and many don't live longer than that. They are the type of species that is a live, fast, die young type species.

00:17:39
Speaker 5: It's true.

00:17:39
Speaker 4: You can have some species that take a long time to mature and they take a long time to reproduce, and that's a long lifestyle. Their life history is much more compact. A pocket mouse that is born in the early part of the season can go on to reproduce that same year, so there can be grand offspring of one of the mice that we release, oh wow.

00:18:01
Speaker 5: Within the same year if we time it right.

00:18:03
Speaker 4: And so because of that, and because they are the smallest enamel in their ecosystem, there are a lot of things that eat them, and so there are a lot of threats out there, natural ones, but means that they do not have long life spans. What we've been able to do in human care is expand that life span due to the wonderful veterinary team we have here and those are also our welfare teams. That are really thinking about how we give them the best life possible.

00:18:30
Speaker 5: And we now have.

00:18:32
Speaker 4: The world's oldest mouse and human care, not just world's oldest pocket mouse, but world's oldest mouse ever in human care. And his name is Patrick Stewart and he is over nine and a half years old and still going. So we were very lucky to have some recognition from the Guinness Book because it's something that our teams have been working on for a long time to be able to sit back and realize what they have accomplished with that, and he really is the flag bear for all of the wonderful care and the species that we have here.

00:19:03
Speaker 2: Hold up, wait, did you just say Guinness Book. That was one of your hints, MARKO. Guin us Book a world.

00:19:09
Speaker 1: Record, Yeah, yeah, totally was just a few months ago.

00:19:12
Speaker 3: Pacific pocket mouse Patrick Stewart was awarded for his longevity at nine years, two hundred and nine days in February, making him officially recognized by the Guinness Book of World Records as the oldest living mouse under human care.

00:19:28
Speaker 1: Snaps for Patrick.

00:19:29
Speaker 2: Stewart and now finally all of your hents, even threepennies and Guinness Book of World records. If it all makes sense.

00:19:38
Speaker 3: I'm really stoked you forget it all out, friend, and right as we were wrapping up this episode, but before that, I want to ask Allison if there's anything we didn't cover that she'd like to add.

00:19:49
Speaker 5: That's a good question.

00:19:50
Speaker 4: I think it's very easy to look at.

00:19:54
Speaker 5: A mouse and think why do I care?

00:19:56
Speaker 4: But really, the more you learn about pocket mice, there are so many unique features to them that make them really incredible. And that's the case with many of these less charismatic species that may not be the poster child for a lot of our efforts, but.

00:20:11
Speaker 5: They really are incredible in their own way.

00:20:13
Speaker 4: I'd say a lot of our ongoing work really tries to both better understand them as a species but reveal more of these things that make them truly what they are.

00:20:22
Speaker 3: What is it that you like most about the Pacific pocket mouse.

00:20:26
Speaker 4: I think they are just an incredible example of a very well adapted species, and every species is adapted to its specific environment.

00:20:36
Speaker 5: But the more we learn about how tied they are.

00:20:38
Speaker 4: To this ecosystem, it's just been incredible and a journey for me really to see those connections and really see them as part of the ecosystem and how they weave into that big picture.

00:20:48
Speaker 5: Yeah, that's been great, Machisie.

00:20:51
Speaker 3: Let's get asked us, Alison. You've given us great insight to these mighty little.

00:20:55
Speaker 2: Nice Yes, Alison, thank you so much, amazing insight. Indeed, we are so fortunate to have been able to learn so much in Marco. Although your hints didn't help me going into this episode, I appreciate discovering it along the way what they were for.

00:21:09
Speaker 3: Thank you friend, Thank you friend, Thank you for playing back the way.

00:21:11
Speaker 1: I'm glad that you enjoyed it.

00:21:13
Speaker 3: And honestly, I learned a few things myself, like I had no idea that they don't drink water and just get the hydration they need from the seeds that they eat.

00:21:21
Speaker 2: Yeah, you know. And speaking of that hydration, the whole part about how their tunnels and burrows help with soil hydration so the plants can thrive really highlighted how important these little mice are to their ecosystem exactly.

00:21:34
Speaker 3: We sometimes only see how wildlife lives off of the plants and their habits at but the more we learn, the more we see how each species is an important part.

00:21:42
Speaker 1: Of the whole ecosystem. In this case of the Pacific.

00:21:45
Speaker 6: Pocket mouse, not only do their burrows help water reach deeper into the soil, but their seed sashes that go uneaten help disperse the seeds and create new growth for native plants.

00:21:56
Speaker 2: Truly a little mouse that matters.

00:21:59
Speaker 1: Love it, they really really are.

00:22:01
Speaker 3: I know I learned a few things, and I hope everyone listening today did too.

00:22:05
Speaker 2: I know I will forever remember the only weigh as much as three pennies.

00:22:09
Speaker 1: I know mixed me.

00:22:09
Speaker 3: Want to go find three pennies. Maybe I'm gonna check my couch and find out the feel of it, right, how little that actually weighs?

00:22:16
Speaker 2: Exactly? Me too, I was thinking of the same, like, where can I find three pennies? Who has coins anymore? I'm gonna find them. I'm gonna find three pennies. I' gonna carry him around some little pocket mouths. It's so cool, all right? Everyone, be sure to subscribe and tune into our next episode, in which we uncover some curious facts about one of South America's well known reptiles.

00:22:37
Speaker 1: Marco Lent and I'm Rick Schwartz.

00:22:39
Speaker 2: Thanks for listening for more information about the San Diego Zoo and San Diego Zoo Safari Park. Go to SDZWA dot org. Amazing Wildlife is a production of iHeartRadio. Our supervising producer is Nikia Swinton and our sound designer and editor is Sierra Spreen. For more shows from iHeartRadio, check out the iHeartRadio app, Apple Podcasts, or wherever you listen to your favorite shows.