Pacific Pocket Mouse: Little Creatures, Big Impact

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Speaker 1: Hi, I'm Rick Swartz and I'm Ebony Mone. 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 I Heart Radio and San Diego Zoo Wildlife Alliance, in international nonprofit conservation organization that oversees the San Diego Zoo and Safari Park, and we have a great show for you. Today. We're talking about one of the smallest mammals in North America, the Pacific pocket mouse. You'll learn interesting facts and coming up we'll talk about the San Diego Zoo Wildlife Alliances efforts to save it. Pacific pocket mice are the smallest mouse species in North America. But Rick I was surprised to learn they get their name from something else. Yes, it's true. Some people even think they're so small you can fit in your pocket. That's how they got their name. But in all honesty, the Pacific pocket mouse got its name from external fur line to cheek power coaches, in which it carries seeds their primary food source. These pouches are different than what you see in squirrels or hamsters, since the pouches for those animals are inside the mouth. So where do these tiny mice live well, have any The Pacific pocket mice are very specific on where they can thrive. There are species that lives in our own backyard right here in southern California. The population we specifically work with lives in Laguna Coast Wilderness Park and at the Marine Corps Base Camp Pendleton. They live in a very specific coastal ecosystem that is no further than two and a half miles from the beach, usually in sandy areas known as coastal strands, coastal dunes, and coastal sage scrub, made up of low growing plants that do well in coastal lowlands so close to the Pacific Ocean. Yes, so these tiny mammals are small, but I understand they're important. Rick, what's the importance of the Pacific pocket mouse for the environment? That's a question we actually hear about a lot of small rodents because I think we as humans center liquor rodents is sometimes being a pest, But in all honesty, small rodents like the Pacific pocket mouse play a very important role in the ecosystem. They are a great food source for many other species, but also specifically to the pocket mouse because their main diet is seeds. They will spend all night collecting nose seats. They'll eat some of them, but they'll stash the rest in underground chambers for future use. Now, of course, they don't eat all of them for future use. Some of those seeds will eventually sprout, and so they are actually sort of a maybe a little agricultural specialist for their environment. So very important for the plants also than which of course, all animals rely on in that ecosystem. So what threats do Pacific pocket mice face in the wild. Unfortunately, one of the biggest challenges the Pacific pocket mouse faces right now is the loss of habitat. We mentioned they love that beachfront property. That swath of of land that runs along the coast is prime real estate for humans as well. We like to develop it and live there. So we have a challenge for these little mice finding areas where they can live safely. So Rick, just how small are Pacific pocket mice? I believe it or not, they are one of the smallest living mammals in North America. They weigh in at a whopping Are you ready for this? Six Grahams or if you are more of an ounces person, that's point zero four ounces. So they're pretty tiny. And speaking of tiny, two when doing some research on this, I've found that scientists also know for a fact their little footprints are only three millimeters wide. That's smaller than half a centimeter. I can just imagine a scientist trying to measure a Pacific pocket mouse is foot. How exactly do we know for a fact that the Pacific pocket mouse is foot is just that small. Yeah, they don't actually pick them up and try to fit them for shoes or anything like that. They're part of the research in which they do to find out more information about the species. They set up some tubes out in the wild with a little bit of food for them, and in that tube then it's well, therefore it was a passive method of measuring. In that tube, there is a little bit of ink and a little bit of paper, and so as they go through to retrieve the little treat that's in that tube for them, they walk right across that walk back out and they leave a little footprint they could be measured. Wow, so we know they have a unique way of storing their food and they're tiny. Is there anything else that makes the Pacific pocket mouse unique? Well, I think I think this is a fun fact, especially for an animal that's known for living in the coastal areas of Southing California, which we all can agree, or usually where people go for winter break. You know, it's kind of nice and mild. But if in the winter, environmental factors are unfavorable, which for the Pacific pocket mouse, that usually means it's been a very dry season, so perhaps not as much food is available. The pocket mouse will hibernate underground until spring brings better conditions for them more or basically more food from the rains. But if adequate food supplies are available all year round, the mouse will remain active during the winter. Amazing break. The Pacific pocket mouse has a sort of a comeback story. At one point they were considered extinct. Yes, Ebony, they do have an amazing comeback story. They were believed to be extinct for twenty years and rediscovered in so coming up, we will talk about the ongoing efforts of the San Diego Zoo Wildlife Alliance and our partners to protect and save them all. Right now, it's time for the San Diego Zoo Safari Park minute an opportunity for you to learn what's new at the zoo. After more than four decades of successfully re introducing California condors and other vultures back into their native habitats, San Diego Zoo Wildlife Alliance is ushering in a new era of vulture conservation. Wildlife care specialists at the San Diego Zoo Safari Park have begun raising the Western Egyptian vulture in endangered species native to Southern Europe, Asia, and Northern Africa. Did you know the program first successful hatching came in specialist named the hatchling Jamila. It's the first of its kind hatching in North America. Wildlife Care specialists to use life like hand puppets resembling an adult vulture to pass food to Jamila, to help her inexperienced parents and to make sure she didn't develop an attachment to humans or spotlighting. The smallest mammal in North America, the Pacific pocket mouse, San Diego Zoo Wildlife Alliance scientists have worked to increase populations once found from Los Angeles to the Mexican border. Let's chat now with Dr Deborah Shire, who leads the San Diego Wildlife Alliances Pocket Mouse Conservation Program dr SHIRE high. For twenty years, scientists thought Pacific pocket mouse were extinct. How did that happen and what's their current status? So the species was documented through survey efforts from nine different locations along postal southern California from way back in eighteen ninety four to nineteen seventy two. That survey efforts did not find them for twenty years from nineteen seventy three to nine three, and because of that it was presumed extinct. It was rediscovered during a survey effort in nine at the Dana Point Headlands, and then two additional populations were rediscovered on Marine Corps based Camp Pendleton in the mid nine nineties. So as far as population size, we really don't have a good estimate for this species. It's really in large part because the species populations go through boom and bust cycles, likely in response to precipitation and the resulting vegetation growth. So, for example, in the Dana Point population, there were only two individuals documented in two thousand and five, but by two thousand and twelve there were over seventy five individuals. To make an educated guess, I would say across the species range, there are likely just a few hundred individuals remaining right now in three extant populations. And because we've been experiencing drought years for years here in southern California, reproduction has been extremely limited. So what other threats do they face? Well, they're a primary prey species for a variety of predators in the area. Um and while they are adapted to dealing with native predators, there are a variety of other threats, including non native predators like the house cat. Most threats that are associated with the Pacific pocket mouse are really driven by the presence of humans, non native grasses that were brought in from Europe for agriculture and grazing, night lighting that we put out of our homes roads, and like I said, the presence of pets associated with our homes like house cats and dogs can be a problem. Now, it doesn't mean that they can't coexist with humans, just that humans really need to change our behavior to be able to coexist with wildlife like the Pacific pocket mouse. So, for example, if we you know, manage non native grasses and try to keep the habitat more native, keeping our lights off at night, and our cats inside could also help. Why is the Pacific pocket mouse important? Pacific pocket mice play a really important role in ecosystem function. So they are granivores which means their seed eaters and their semi fossorial meaning that they dig burrows and they live part of their life underground because they collect and cash native seeds and they store them away for later date when food might not be so plentiful. They are thought to be primary seed dispersers of the native plants, which continues plant growth and expands those plants in the native coastal sage scrub ecosystems in which they live. In addition to dispersing native seeds, they're digging activities, increased soil hydrology and nutrient cycling which helps those plants thrive. And as I mentioned, they are prey for a variety of species. Almost everything eats them out there, including native owls, terrestrial mammals like bobcats and coyotes, probably skunks, snakes, and even trantula eat them. So without them, these species wouldn't have as much food to eat, so they're really important for ecosystem function. Can you talk a bit about the reintroduction process and what all goes into that. Absolutely, there were hundreds of surveys done to try to find Pacific pocket mice throughout the historic range of the species, and as I mentioned earlier, there are only three extamp populations that remain, and to ensure that a large scale catastrophic event doesn't wipe out the species, the goal in the recovery plan for the species was to establish ten viable populations to sort of spread the risk of extinction. But those hundreds of surveys found only three extamp populations, so we needed to do population creation in order to reduce the probability of extinction, and we've we've started out trying to determine whether there were enough animals in the extamp populations to do a wild to wild translocation, but there weren't. There were just not enough animals and the source populations to be able to collect from them and not imperil those populations. So back in two thousand and twelve, we established a conservation breeding facility for the species at the San Diego Zoo Safari Park. We collected thirty individuals and we grew those numbers in the conservation program from thirty to over a hundred within a few years. It was a little tricky because the animal is a solitary species, so sort of like a little panda, where they are territorial and sent is used to for females to determine which individuals males they would like to mate with, so it's it's sort of tricky. You have to wait for a female to come into esters and then she has to pick a particular male to breed with, but if she doesn't like him, she might try to kill him. So there's a lot of effort that goes into breeding them. But we grew the execute population up to over a hundred and allowed us to start rein reducing them into the wild. In ten we started those efforts and our first relocation was into Laguna Coast Wilderness Park, so we released fifty that year and it's not been without its challenges. They are a praise species, as I mentioned, so not only do they have a lot of predators that would like to eat them once we've put them out there, but we also have potential competitors. There are several other rodent species in the community that can outcompete them since they're the sort of tiniest gye on the block. But we've been successful. We've learned a lot over the last five six years, and we're in a place now where we've learned that if we get them out early in the season, the females actually can reproduce in the months right after we release them. So we have wild born pups at the reintroduction site in the year that we've released them, which is very, very, very exciting. It's one of the first metrics that we use to evaluate reintroduction success survival. But then population growth is really important, and in the last year we managed to get the population to overwinter successfully and we had reproduction for a second year this last year, so we're feeling pretty optimistic about how well we're doing with establishing a new population, so a fourth population on on the landscape. Dr shire Um, can you back up a little bit and tell us what exactly is meant by wild to wild translocation. Wild to wild translocation is just when you collect founders for creating a new population. They can either come from an extent population in the wild, meaning that they're present in the wild, they're already born in the wild, and then you can relocate them to a new site. There are benefits to doing that because those animals are already for familiar with all of the important environmental cues that there are in the wild, and they're probably pretty savvy behaviorally, right, they have good survival skills because they were born out there. Animals that are sourced for a relocation from an exit population or human managed population can also be successful in relocation efforts, but they require extra care and extra preparations. So when we read them in human care, those animals don't have all of the important environmental cues that the animals that are born in the wild. Hat We do our best to replicate key environmental cues like seasonality through skylights and day length, and also availability of you know, scent of con specifics or hetero specifics, or even exposure to some predators in a controlled context. But we might need to and we have needed to train them to develop those effective survival skills before they go back out into the wild. So there's a few more steps for at least for pocket mice that we need to take in order to make sure that they have effective survival skills before they go into a new site when they're sourced from a human managed population. So what all goes into teaching a Pacific pocket mouse, how to better survive in the wild, how to detect and avoid predators. So for detecting and avoiding owls, they are an aerial predator, and so often animals have a natural overhead fright response. So we just give them a single exposure to an owl on a pulley system that flies over the top of their head and they will jump and avoid and hide in in shelter without any training. But for the snake, it's sort of a different story. What we do in our facility is give them exposure to the snake, and we we pair that exposure with the spray of water. So and they really hate getting sprayed with water. So when when they approach a snake, a king snake, we give them a little sport of water and they go running away. And then we we test them again with the snake over time to see that they don't continue to approach the snake, that they stay farther away, which is our goal. Ebony. I have one more thing that I'd like to share, if you don't mind. Often people ask me why are we saving rodents? And you you sort of alluded to that question a little bit earlier, and I talked about their importance in the ecosystem, and I would just say that while they're not a charismatic mega fauna like a lion or a rhino that we have at the Zoo, they are a part of our history in California and they I like to think of them as parismatic mini fauna and they're really play an important role in the ecosystem and if we lose them, we stand to lose a part of California's natural history and all the beauty and diversity that comes with beautiful answer. Congratulations to you and your team. We've been talking to Dr Shire with the San Diego Zoo Wilife Alliance. Thanks for telling us more. Thank you, and that's our show for today. Thanks for listening, and be sure to subscribe and tune into next week's episode, in which we bring you the story of the gardening King of the Jungle, the gorilla, the largest of all the primates. I'm Empenny Money and I'm Rick Schwartz. Thanks for listening. For more information about the San Diego Zoo and San Diego Zoo Safari Park, go to sdz w a dot org. Amazing Wildlife is a production of I Heart Radio Our producer is Nikias Winton, and our executive producer is Marceda Pina. Our audio engineer and editor is Amita Gnatra. For more shows from my Heart Radio, check out the I Heart Radio app, Apple podcast, or wherever you listen to your favorite shows.