Have you ever noticed that oak trees sometimes have bumper crops of acorns, and sometimes hardly produce a thing? What causes this? And why?
Join host Griff Griffith and producer Michael Hawk on an exploration of acorn masting (bumper crops), with a special deep dive into one species that profoundly benefits – the charismatic Acorn Woodpecker.
Guided by our special guests, Dr. Walter Koenig (both a masting and Acorn Woodpecker researcher), and Dr. Doug Tallamy (author of The Nature of Oaks), we tell the tale of acorn masting, and the importance of oaks in general.
This episode is part of a playful exercise in community podcasting, with 6 different shows each producing their own stories about or inspired by the mystery of masting, and releasing them at (approximately) the same time.
For other masting stories, check out:
- Future Ecologies
- Golden State Naturalist
- Learning from Nature: The Biomimicry Podcast
- Nature’s Archive
- Outside/In
We’ll populate this Spotify playlist with all our stories as they come out!
Beyond a podcast, Jumpstart Nature is a movement fueled by volunteers, igniting a fresh approach to reconnecting people with the natural world. In the face of our pressing climate and biodiversity challenges, we’re on a mission to help you discover newfound purpose and motivation.
Join us in this vital journey towards nature’s revival. Explore more and show your support at jumpstartnature.com, and follow us on Facebook, Instagram, LinkedIn, BlueSky and YouTube.
For even deeper nature insights, delve into our companion podcast, Nature’s Archive.
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Links to Topics Discussed and Supporting Resources
Calscape – find hyper-local native plants in California
Homegrown National Park and their Map
Related Podcast Episodes
Credits
This podcast episode was written and produced by Michael Hawk. Our host and co-writer is Griff Griffith. Kat Hill provided editing support for the interview with Dr. Walter Koenig.
Some of the music used in this production is through creative commons licensing:
Transcript (Click to View)
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[00:00:00] Griff Griffith: Growing up my grandma was my best friend. We even made up our own religion called the Church of whatever and Oak Trees. We were the only two members. The Valley Oak was our symbol. We even had a sacred book that only existed in our heads, but it was called the Gospel of the Oak as an 8-year-old. My most sacred place was on a wooden palette that was lodged in the branches of an ancient valley oak.
My grandma couldn’t climb this tree, and anyone else who tried was pummeled with acorn grenades and or oak gall bombs.
We chose the oak as our religion symbol, not just because they’re beautiful trees, but also because my grandma told me that our ancestors only survived Ireland’s potato famine because they ate acorn mush up until the moment they stepped on the boat that brought them to America.
Grandma assured me that the more time I spent among the oaks, the more mysteries I would discover. And she was right first time I found an acorn Woodpecker’s Grainery, I thought that someone had [00:01:00] shot that dead tree with a machine gun that used acorns as bullets. But it wasn’t long before I noticed Acorn Woodpeckers standing guard over them even fitting the seeds into place.
I called the old snag woodpecker’s kitchen and gave the birds plenty of space.
Years later, as a Nature Conservancy restoration intern. Part of my job was to collect acorns for our restoration site . . My boss said we were lucky ’cause the oaks along the Sacramento River were masting that year. I nodded. Like I understood, but I really didn’t. It was the first time I remember hearing that word, but once I was crawling around in the grass and Finding tons of acorns to drop into the bucket . I figured out what Masting meant. It wasn’t just one oak tree producing a monster amount of acorns that year. It was all the trees in the area.
If each acorn were a quarter ,, I would’ve been a millionaire.
It took little time to fill 10 buckets and I never felt like I was stealing wildlife’s food. There were more than enough acorns for all of us.
These [00:02:00] synchronized boom years or masting events are a fluke of nature, a manifestation of weather.
Or a carefully derived strategy among oaks. Wherever the evidence takes you, you will immediately see that the benefits to the oaks is obvious, overwhelm the scene, with numbers, and some acorns are bound to sprout.
In the gospel of the oak chapter 10, verse 15, it says, an oak or a grandson that tries to mast every year wears itself out. Learn when to store your energy and when to share it.
That’s how you last long enough to shade others.
Today’s episode is part of a playful experiment in community podcasting.
Six different shows are each producing their own stories about, or inspired by the mystery of masting and releasing these episodes at approximately the same time. It’s a critical mast of podcast, if you will.
so be sure to check out Future Ecologies, Golden State Naturalist, Outside/ In and Learning from Nature, [00:03:00] the Biomimicry Podcast for their releases. And you can hear the full interviews with our guest today on the Nature’s Archive Podcast. And by the end of this episode you will be a master about masting. Get it? Okay. Sorry. Let’s jump in.
I’m Griff Griffith, and welcome to Jumpstart Nature.
Quick heads up. Our founder and producer Michael Hawk is the one who facilitated these original interviews. So to give you the most cohesive story today, Michael’s going to personally guide us through the clips. Take it away, Michael.
[00:03:47] Michael Hawk: Do you remember childhood encounters with acorns? They’re Robust and polished, like a classic artist carving with cute caps that can hardly be ignored and from the acorn grows a tree sometimes immense, sometimes [00:04:00] living hundreds of years. Other oaks might only grow a few feet tall when considering the 90 species of oaks native to the United States and the 500 worldwide.
I could rattle off superlatives all day long. But some of the most important facts about oaks are harder to see. Life on earth nearly always begins with sunlight, and somehow the sunlight’s energy has to be converted to calories for plants and animals. Of course, that begins with photosynthesis.
When ecologists look at ecosystems, they estimate that about 10% of the energy produced by plants gets passed along to herbivores the plant eating animals.
[00:04:38] Doug Tallamy: The 10% is a general estimate that has been challenged for about 50 years, . Um, it could be somewhere around there
[00:04:46] Michael Hawk: You might recognize that voice. It’s Dr. Doug Tallamy, author of The Nature of Oaks.
[00:04:52] Doug Tallamy: but yeah, I, I would say definitely the oaks are punching above their, their weight class. You know, it’s about how much of the energy [00:05:00] from the sun you are willing to share with other organisms.
Oaks share a lot.
there are other plants, even other native plants that share very little, like ferns, for example, ancient, ancient plants. But they, they’re really good at protecting themselves.
They, they grab that energy and they don’t share it. So, uh, if you’re trying to support a food web in your local ecosystem, you’re not gonna do it with ferns. You are gonna do it with, with oaks
[00:05:24] Michael Hawk: I know one big area of focus is their larval food plants for, a great variety of insects.
[00:05:31] Doug Tallamy: Right. And that is, that’s really, uh, one of the primary reasons, , I got interested in oaks. It’s not just insects, it turns out it’s caterpillars. Um, caterpillars transfer more energy from plants to other organisms than any other type of plant eater.
So if you don’t have a lot of caterpillars in your ecosystem, you, you essentially have a failed food web.
Why do we need so many caterpillars? Well, let’s just focus on birds. It takes thousands and thousands of caterpillars to make one clutch of breeding bird. You know, we, we got a lot of data for chickadee, but there’s data on a [00:06:00] number of other things.
6,000 to 9,000 caterpillars to get one clutch of a bird that’s a third of an ounce through to independence, actually just to, to fledging. And then the parents continue to feed them caterpillars another 21 days. So you’re talking about tens of thousands of caterpillars required to make a nest of chickadees.
nationwide Oaks support more than 950 species of caterpillars
[00:06:22] Michael Hawk: The impact of caterpillars is undeniable, but one of my favorite things about oaks are growths called galls. Sometimes tiny and cryptic. Other times, boastfully large and colorful.
They can sometimes adorn an oak tree by the thousands. Now, just a few seconds ago, I called them growths. But that simple characterization really shortchanges what they are.
[00:06:43] Doug Tallamy: People have likened galls to cancerous growths on plants, but I don’t like that analogy because cancers grow.
I mean, tumors just keep growing in an uncontrolled way
[00:06:55] Michael Hawk: It all starts with a tiny wasp. In fact, it’s a special group of wasps who rather than [00:07:00] sting have unique ovipositors. Think of it like an egg laying tool. These wasps seem to emerge at just the right time when the oak tree has buds at just the right stage or when a leaf is at the perfect stage.
[00:07:14] Doug Tallamy: the female wasp injects into the buds of the. The ma thematic tissue. The bud of an oak is like, like stem cells. You can make it into anything you want.
And they inject, hormones in different ways that create the shape and the size of this species specific gall. So it’s, it’s highly defined. You can identify what species of wasp it was that made the gall just by the shape of the gall.
[00:07:38] Michael Hawk: Yes, the wasp through some sort of chemical alchemy developed through eons of evolutionary experimentation, instructs the tree to grow a very specific growth inside of which the wasp larva set up shop in their new home. They have protection and free food courtesy of the tree. And the galls, depending on the species, [00:08:00] can look like strawberries, tiny red volcanoes, little convoluted brains or large apples, just to name a few of the shapes and sizes.
While oaks haven’t covered the gall real estate market, there are other trees that do this as well, and other plants for that matter, they are some of the most prolific gall supporters and where there are defenseless larva, there are sure to be predators of all shapes and sizes as well.
I’ve even seen woodpeckers probing inside of Galls looking for a treat. Maybe a bit like nature’s gumball machine, but when we think of woodpeckers and oak trees, one species stands out.
That’s the sound of an acorn woodpecker, a gregarious bird found in the southwest and western United States. And in fact, all the way through Mexico and down into Colombia.
[00:08:53] Dr. Walt Koenig: they are quite vocal They make a lot of fun noises that make them very conspicuous,
acorn [00:09:00] woodpeckers are typically described as being clown faced. They do have a clownish type of visage, if you will
[00:09:09] Michael Hawk: Dr. Walter Koenig is perhaps the world’s leading expert on acorn woodpeckers.
I
[00:09:13] Dr. Walt Koenig: they have these tongues, that go all the way around their heads so that they can stick them out, strikingly long distances. Back when I used to have a bird that I could show people, I would pull out his tongue and, it would go an amazing distance given that,
as birds, they aren’t that big.but they use that. They have a little barbs at the end. Uh, most woodpeckers, which are wood boring and are pecking into wood, looking at wood, trying to find wood boring insects will use that to pull out those insects
Acorn woodpeckers are what we call cooperative breeders. Cooperative breeding is, not terribly unusual, but pretty interesting social behavior [00:10:00] found in maybe 10 percent of bird species, but it’s quite uncommon in North America.
[00:10:06] Michael Hawk: Part of the reason why acorn woodpeckers love oak trees is because old mature oaks often have lots of holes, perhaps where branches fell off or maybe where other woodpeckers excavated.
[00:10:17] Dr. Walt Koenig: Acorn woodpeckers are cavity nesters, and they also roost together in cavities throughout the year.
They are communal roosters. They live in family groups, and In some cases, the entire group will roost together in the same nest cavity, though sometimes they’ll split among more than one roost cavities on their territory.
[00:10:39] Michael Hawk: and surprisingly,
[00:10:40] Dr. Walt Koenig: Acorn woodpeckers are largely fly catchers, so they’re spending a lot of time fly catching up in the air.
They also leaf glean and bark glean in particular. One of the old names for them was ant woodpecker, and in fact they eat a lot of ants, which are often on the trees, living up in [00:11:00] the trees around here.
[00:11:01] Michael Hawk: oaks in their habitats support lots of insects. So it makes sense. But their name, Acorn Woodpecker came about from a much more obvious reason. Yes, they do eat acorns too.
In fact, acorns are their foundational food, perhaps like rice and wheat are for people.
[00:11:18] Dr. Walt Koenig: Acorn woodpeckers are tied to acorns and oaks, and part of it is that they have developed a striking habit of drilling individual holes in,
[00:11:30] Michael Hawk: And was that a pun by the way, a striking
[00:11:33] Dr. Walt Koenig: I mean, well, yeah, okay, I’ll accept it. A striking habit of drilling these These individual holes in the dead tissue of trees. Uh, and other structures. They, of course, are well known for doing this in buildings and, and people’s houses Telephone
poles. so they’ll drill these individual holes that they’ll then harvest acorns in the fall as they’re [00:12:00] maturing and put them in these little holes. Now, the point of that. as I said, is that it has to be in the dead tissue of a tree. So it’s always in dead limbs or the bark. It has to be in a species of tree that has relatively thick bark where they aren’t piercing into the living tissue of the tree, because they, the whole point is that they’re doing this in the late fall, early winter, when around here in California, uh, that’s when it starts getting wet and cold and rainy. And the whole point is to allow these acorns to dry out and to not rot and mold during the winter
[00:12:42] Michael Hawk: Now when you think of woodpeckers, of course you imagine them drilling holes, but surprisingly,
[00:12:47] Dr. Walt Koenig: They aren’t really good at drilling holes, cavities, but they, they do it. And so they’ll drill a few dozen hundred of these a year, and they’ll just keep doing it. They’ll reuse these [00:13:00] these holes over and over again during the winter and each year when the acorn crop matures. And so if they happen to have a nice. tree, that is going to be around for a while, they can end up with a, granary, as we call them, that has tens of thousands of holes. These big granaries, , which end up being kind of famous because they can be pretty striking,are not all that common because These birds are trying to drill these holes as fast as they can, just to make up for holes that are being lost for one reason or another, because often the limbs are falling during the winter, the tree is falling apart, You know, they have to work pretty hard to maintain a granary that’s going to have a thousand, a couple thousand holes, and allow them to last through the winter and the spring.
[00:13:54] Michael Hawk: kind of like with gall larvae, we’re now talking about a great food source stuck in one place. [00:14:00] No wonder Acorn woodpeckers live in family groups.
They need labor to protect and manage the granary.
[00:14:07] Bernard: Good Morning Ralph
[00:14:08] Vernon: Good Morning Sam
[00:14:10] Dr. Walt Koenig: They certainly check on the acorns. as they dry out, they shrink, and the birds spend a lot of time in in the winter just sort of checking on them, and if they don’t fit very well anymore, they will pull them out and move them to a hole where they fit better, because then they do also spend a lot of time defending them against the titmice and the quail and the ground squirrels. And everything else that might come and want to steal those acorns when they are no longer available on the oaks themselves. Because by the time you get to January, and February, and March, and later, in a typical year, those are the only acorns that are going to be around. And so there are a lot of animals out there that would like to get those acorns. And of course, having them, Carefully packed in those [00:15:00] granaries makes them difficult for anybody else to get them, and the birds then defend them against all these other species. As well as other acorn woodpeckers that might want to come and try to steal them.
One of the really interesting things about the geographic distribution of acorn woodpeckers, is that they are not, strictly speaking, restricted to places where there are oaks. They tend to only be found in places where there are at least two species of oaks,
[00:15:30] Michael Hawk: And this brings us back to masting.
[00:15:32] Dr. Walt Koenig: The reason for that oaks, are masting species. They produce a lot of acorns, a lot of seeds some years and very few seeds other years. And if you’re living in a place where there’s only one oak species, you’re going to have what amounts to an acorn crop failure fairly regularly, once every three or four years, which is basically once a generation, if you’re an acorn woodpecker. And acorn woodpeckers just apparently are not able to make it [00:16:00] in most such places. Whereas if there are two or more species, the species do not necessarily produce acorn crops synchronously.
[00:16:07] Michael Hawk: Dr. Koenig has spent many years studying masting.
[00:16:11] Dr. Walt Koenig: So masting is the variable and synchronized production of seeds of plants, and so, I’ll talk mostly about trees because that’s where it’s been most studied and what I’ve been most interested in.
So the interesting thing about masting is it’s not strictly speaking something that an individual tree does. So a tree may produce a lot of acorns one year and not very many or no acorns another year. But masting is a population level phenomenon. It’s something that all the trees in the population are doing more or less at the same time. So in a good mast year, all the individuals Of whatever species we’re talking about, are going to produce a relatively good acorn, crop whereas in a bad mast year. [00:17:00] none none of them, or very few of them, are going to produce any acorns at all.
how does a population of trees decide when it’s going to produce to put all its energy into acorn production?
[00:17:11] Michael Hawk: I’m sure that’s the question we were all thinking.
[00:17:14] Dr. Walt Koenig: those factors can be similar among some species so that you can get some synchrony in acorn production among different species. But one of the things that really sparked my interest early on was this definition, which was synchronous production of seeds by a population of trees, but what no one seemed to really care too much about or have spent a lot of time studying was how big a population we were talking about. So was it just the trees right here at Hastings? These trees that we have here, including Valley Oaks and Blue Oaks, found all around the state, around the Central Valley of California. So they cover millions of [00:18:00] acres. And so if it’s a good acorn year for Blue Oaks here in Hastings, is it a good year up in the Bay Area around Oakland and the Berkeley Hills?
Is it a good year in the foothills of the Sierras?
so it took us a long time before we kind of realized that, in fact, the population we were dealing with was much larger than people had suspected. And, in fact, for some of the species, at least, it pretty much encompasses their entire geographic range
[00:18:32] Michael Hawk: So what is driving this large scale event?
[00:18:35] Dr. Walt Koenig: the 2 things that are the most important for, say, the valley oaks, or the blue oaks, uh, which are species, which at least a lot of your listeners here in California will be familiar with, conditions during the spring, when they’re flowering, so these are species that are flowering in February and March and April, and then those flowers that are what, then mature into [00:19:00] acorns the next, fall. And so the conditions during the spring are very important. And then the complicating factor and the one that sort of really makes things difficult is that it also depends on, what the acorn crop was the year before
So if they put a lot of energy into and had a very good acorn crop last year, then they tend not to have a very good acorn crop this year. And this is what really tells us at some level that part of the story is that they’re storing energy somewhere in the tree
[00:19:34] Michael Hawk: so the weather’s the main driver,
[00:19:37] Dr. Walt Koenig: In fact the weather is probably the main driver of what’s going on.
[00:19:42] Michael Hawk: So the oak trees need to have the right weather conditions to build up energy and the right conditions to allow for pollination and production. Of course, the cycles might be a bit different where you live, but the principle remains the same.
We only talked about acorn woodpeckers, but so many other animals partake in [00:20:00] acorn treats from blue jays and scrub jays to crows and turkey, squirrels, wood rats, and mice love a good acorn too. But did you know that white-tailed deer are some of the most prolific acorn eaters? And black bears can gorge up to 10 pounds of acorns per day when preparing for hibernation?
But despite all of the connoisseurs, a great many acorns will end up lost, buried by a squirrel or a jay and sprout into the next generation of oaks continuing this ancient cycle.
[00:20:30] Griff Griffith: So what’s the big lesson we can take from today? Well, masting is a reminder that the natural world operates on long, complex cycles that we don’t often even see. It takes years for an oak tree to budget its energy for that giant synchronized boom year, and when it happens, the entire ecosystem from the smallest ground squirrel to the amazing Acorn woodpecker is riding that wave.
We’re all part of this massive, invisible, critical event.
My call to you is [00:21:00] simple. If you want to support this whole, beautiful, ancient, complex system right outside your window, plant an oak. It’s a gift to the future and a keystone home for hundreds of species.
Be sure to check out our show notes for links to resources to help you find the right sized and right species of oak for your area. check out the full interview with Dr. Walter Koenig over on Nature’s Archive Feed right now. There is so much more to the fascinating story of acorn Woodpeckers that you just have to hear to believe.
[00:21:29] Michael Hawk: The Jumpstart Nature Podcast was created and produced by me, Michael Hawk.
Special thanks to Kat Hill who provided editing support on the Walter Koenig interview, and of course, Griff Griffith, our host.
Thanks for listening.
[00:02:41] Mike Armer: They’re perfect little killing machines.
[00:02:43] Griff Griffith: That’s Mike Armer.
[00:02:45] Mike Armer: I’m a small animal veterinarian, so 99 percent of what we see is cats and dogs.
[00:02:50] Griff Griffith: And like everyone in this episode, Mike is also a cat owner and cares deeply for cats. Even our producer, Michael Hawk, cares for three cats in his home.
[00:02:59] It’s estimated that there are around 60 million pet cats in the United States, and about one quarter of households own at least one cat. And there are as many as 60 to 100 million stray and feral cats. That’s 120 to 160 million cats in total in the United States.
[00:03:16] Obviously it’s hard to census stray and feral cats, and many sources imply that these numbers may be underestimated.
[00:03:22] Allison Fluty: I would say the thing that always surprises me, is the number of cats that will be at a place versus the number of cats that someone has reported. For example, the, there was one big colony that I was working with for a while, It initially started with just one person asking for help near her work.
[00:03:42] Which was up against a creek and she was worried about the cats that were around there. She said, there’s probably like 20 cats and there’s a lot of coyotes around there. She wanted to see if someone can help. , There was more like a hundred cats in that, that whole area. and. It’s the same thing no matter where you go, you know, it’s just the proportions.
[00:04:05] It’s usually like five times more cats than are reported. If I go to a house and they say, I think there’s, you know, four or five cats, it’s like, okay, there could be 15 to 20.
[00:04:15] Griff Griffith: Alison Fluty, who you just heard from is perhaps the ultimate cat lover. She educates the community about outdoor cats and volunteers with a TNR organization in multiple capacities.
[00:04:26] What’s TNR? We’ll come back to that in a moment. But it does not take a mathematician to realize the impact 100 million cats have on wild animals and our ecosystems.
[00:04:36] Mike Armer: Cats are not a wild species. These are a domesticated animal, and so these aren’t ever found in nature. definitely seen a lot of different studies estimating,
[00:04:53] how many animals cats kill, it’s really quite disturbing. The numbers I’ve seen most recently are more than two billion, with a B, birds per year, and more than 12 billion small animals. You know, mice, rats, rabbits, things like that.
[00:05:09] Griff Griffith: Stop and think about those numbers. 14 billion birds and small animals per year killed by outdoor cats, which aren’t even native to our environment. And 100 million outdoor cats, that means there is an incredible density of predators on the landscape, an unnatural density, a density of threat that wild birds and other small animals have never had to contend with before.
[00:05:33] But with 25 percent of American households owning cats and many more caring for outdoor cats, we can make a difference. In fact, what we have to share today might be the most impactful way that you can help biodiversity right after planting native plants, of course.
[00:05:49] I’m Griff Griffith, and welcome to Jumpstart Nature.
[00:06:03] It seems like whenever I bring up the topic of outdoor cats, one of two things happen. People either get really defensive or they get really angry, sometimes both. And it doesn’t matter whether they are conservationists, cat owners, or both.
[00:06:26] Cats trigger polarizing responses in the world of environmental stewardship.
[00:06:31] No matter how you look at it, cats are amazing creatures. They’re independent, yet lovable and loving.
[00:06:37] They are meticulously clean they are stealthy, yet communicate with an incredible diversity of vocalizations and mannerisms.
[00:06:44] They can keep your house or barn free of rodents and help you keep warm at night. And I love getting to know each cat’s personality. Some are playful. Others just love to cuddle. Others are more reclusive. My two cats personalities are so different, it’s almost like they’re two different species of cat. One wakes me up every morning by sitting on my chest and biting my nose. And then as soon as my feet hit the floor, she’s herding me towards the snack jar.
[00:07:09] The other wonders why I live in her house and finds little use for me besides filling her food dish. I love them both.
[00:07:15] Our goal today is to approach this hot button topic with an open and compassionate mind. As you know, I’m both a cat lover and a wildlife lover. If you have an outdoor cat now or care for outdoor cats, there are things you can do to help.
[00:07:31] And after your current outdoor cat goes to the great cat tree in the sky, where there’s everlasting supply of catnip, you can make a pledge that your next feline best friend will be indoors only.
[00:07:42] And speaking of cat compassion, one of the first things I think about is being compassionate for my cat’s health.
[00:07:48] Mike Armer: Indoor cats have been shown time and time again to have longer, healthier lives. The average lifespan for an indoor cat is in the 10 to 15 year range. The average lifespan for an outdoor cat is only two to five years. So there’s a huge difference there. And that’s just lifespan. Quality of life, um, I believe is better for indoor cats.
[00:08:08] They’re far less likely to get sick. They’re far less likely to have significant wounds. It really is a huge difference.
[00:08:16] Outdoor cats, are prone to some infectious diseases, feline leukemia virus. Feline Immunodeficiency Virus, which is cat AIDS. There are others as well. Toxoplasmosis, I know you want to talk about that in a little bit. Wounds, so cats get into fights with other cats. They get attacked by wild animals.
[00:08:38] Raccoons, things like that. Dogs will attack cats when they’re outside. And it’s unfortunately not uncommon for cats to get hit by cars, and that’s almost always a fatal interaction.
[00:08:49] Griff Griffith: Wow. Being an outdoor cat cuts eight to 10 years from their life. And it’s a hard life. That’s for sure.
[00:08:56] Mike Armer: I would say most people have some sense that keeping a cat indoors is better for them and better for the environment. I don’t think very many people have a sense of how extreme the difference is for the cats and for the wildlife.
[00:09:14] Griff Griffith: How do all these cats get outdoors anyway? Well, it’s a combination of things. Sometimes cats are simply allowed to roam free by their owners. Cats might escape , or get lost, or be left behind by owners who are unable to care for them. Just like with other pets, sometimess well meaning owners drop their cats off in natural areas thinking that it’s the best solution. That’s actually how I got my first cat, Meow Meow. She was the daughter of some cats that were dropped off in a city park.
[00:09:41] those abandoned cats aren’t spayed and neutered, then they can, and probably will, start having kittens.
[00:09:48] Each cat litter can have as many as six kittens in it, and those kittens are mature enough to have kittens of their own by the time they’re four to six months old.
[00:09:56] Once there are a few cats in an area, a mature female can have anywhere from two to five litters a year. Well, that’s a lot of numbers, so I’ll do the math for you. A mature female can have as many as 8 to nearly 30 kittens per year.
[00:10:12] You can see how populations can explode this way, and you can see why animals like coyotes might be attracted to these cat colonies.
[00:10:22] You may have heard terms like feral, stray, or community cats, so let’s take a moment to get these terms straight .
[00:10:28] Community cats encompass all free roaming cats, whereas feral represents cats that have little or no human contact. Feral cats tend to fear people and hide and can rarely be socialized That means they usually can’t be adopted.
[00:10:42] Stray cats are typically former pets, so they may be more approachable.
[00:10:46] The reason why these classifications are important is because they remind us that it’s not as simple as just catching an outdoor cat and then adopting it out to a new owner.
[00:10:55] And regardless, there are way too many outdoor cats for shelters and adoption services to handle. Not to mention people willing to adopt them. That’s not to say that adoption isn’t helpful. It certainly can be a piece of the puzzle to solve our cat problems.
[00:11:09] How do stray and feral cats get taken in and adopted out? Very often this process begins through TNR groups.
[00:11:17] Allison Fluty: TNR stands for trap, neuter, and return. Basically trapping a cat, neutering or spaying them, and then returning them to where they came from.
[00:11:26] Griff Griffith: TNR, on the surface, sounds pretty simple , but remember what Allison said earlier?
[00:11:31] Allison Fluty: It’s usually like five times more cats than are reported. You know, if I go to a house and they say, I think there’s, four or five cats, it’s like, okay, there could be 15 to 20.
[00:11:41] Griff Griffith: And Mike Armer adds another wrinkle.
[00:11:43] Mike Armer: From my understanding, TNR works in select situations, specifically where there is a, um, defined community of cats that doesn’t have new cats coming in from the outside. So rural areas that are isolated and don’t have adjoining towns where cats might be coming over from. It can actually work really well there because you can essentially, with time, catch the entire population.
[00:12:13] In more urban areas or larger areas, it’s virtually impossible to get a sufficient number of them to where it makes a difference. From what I understand.
[00:12:25] Griff Griffith: And that makes sense. If you have a large intermingling population, a one and done TNR effort probably won’t be effective in the long run.
[00:12:33] However, people committed to TNR, like Allison embrace much more than a one time trapping effort. Our producer, Michael Hawk calls it full spectrum TNR.
[00:12:44] Some people will also say that returning cats, which are not native to our ecosystems , is inhumane. They will say that we’re picking winners because those cats will continue to hunt and kill native animals. Others say it is inhumane to not return these unadoptable cats because there are no other viable alternatives. And as we stated before, these outdoor cats live short, hard, and often unhealthy lives.
[00:13:10] As you can see, there are no ideal solutions here. But this is where we are in 2025. Facing a situation, where there are millions of free roaming outdoor cats, supported by millions of cat lovers, pitted against wildlife lovers who want to eradicate the cats from the landscape.
[00:13:28] If I could snap my fingers and solve this, I would. But until I gain those magical powers, we have to work with what we have.
[00:13:35] And part of the problem with TNR is that many past TNR efforts have not been full spectrum.
[00:13:42] But in cases where full spectrum processes are embraced, which Allison describes in a moment, it has been successful.
[00:13:49] We’ve linked to a few studies in our show notes. Some of which were done in conjunction with Audubon chapters and bird observatories. One study tracked a population of cats near a city adjacent to the San Francisco Bay. An initial population of 175 cats declined by 99. 4 percent over the 16 year program period. Of the 258 total cats enrolled , only one remained at the end of the program period.
[00:14:17] Allison Fluty: There are a lot of, you know, misunderstandings or why a lot of people think that it just doesn’t work because when you’re doing TNR, you need to get like a hundred percent of the, you want to fix a hundred percent of the is close to a hundred percent. you know, a lot of studies say think like around 80 percent is when you’re going to see, the population start to decline,
[00:14:37] but we always try to do a hundred percent, as close to a hundred percent as possible. And it also requires ongoing management. and so that means that, you know, whoever’s caretaking the cats, the, the feeder, that they’re, feeding responsibly. That’s where a lot of the education comes in again. you know, we tell them don’t just dump food and leave.
[00:14:57] You know, you’re doing it, on a schedule. You’re picking up any uneaten food and taking it with you or throwing it away, and not leaving it out. and that way all the cats in the colony are coming during the times that you’re there and you can monitor them for, any injuries or illness or any new cats that might show up and they’re able to get those cats, and fix them or return them to their owners if they were lost pets
[00:15:21] it is an ongoing thing that requires a lot of education, but if it is done, um, full spectrum, as you say, I like that term, it is successful.
[00:15:29] Griff Griffith: Successful TNR requires getting a handle on the population.
[00:15:33] Allison Fluty: The whole process goes back into like, you have to kind of assess the situation, find out, how many cats are there, find out who’s feeding them.
[00:15:42] A lot of times there’s a lot of different people feeding them that don’t know each other. Provide education to feeders. Depending on the type of area, if it’s like residential, I’ll be going like to all the neighbors houses on the streets and knocking on the doors to ask them if they have outdoor cats or if they’re feeding cats, and leaving flyers if I’m not able to speak to someone in person.
[00:16:14] Using cameras, that we place, they’re kind of like trap cameras. They, they record when it’s, when they sense motion. but you can access them, you know, from an app on your phone. You don’t have to physically get the card out from the camera. All that really is just a, just. to figure out how many cats there are and how many people are feeding them and to get everybody on the same page.
[00:16:34] One of the important things is to establish a routine feeding schedule. You want the cats to be used to eating at one or two times a day. lot of feeders just leave food out and it lets cats come whenever they want. So really shy cats might not show up until 2am or something. There’s a lot of coordination that, that goes into, into that lot of prep before the actual trapping.
[00:17:01] Griff Griffith: Another reason to not leave food out all the time is that you are likely to attract other animals and pests, perhaps roaches, crickets, ants, raccoons, even coyotes.
[00:17:11] Well, meaning people who feed cats take on an extra responsibility as a caretaker, but they don’t always realize this. They need to monitor their feeding stations, clean the stations and ensure that they are not causing more harm. And with this monitoring, people can identify when new cats enter the neighborhood and alert their local TNR group to come back.
[00:17:30] Okay, so when Allison and her TNR group, Bay Area Cats, are engaged, they start with education, establish a feeding schedule, and monitor the population.
[00:17:39] Then it’s time for trapping. Producer Michael tagged along on a recent trap.
[00:17:44] To set the scene, the location is behind a hotel, along a creek, right next to a busy highway in the heart of San Jose, California. After a period of monitoring, Allison assessed that there were 12 to 14 cats, and has been slowly trapping cats over the previous few weeks.
[00:17:59] Allison Fluty: I have two appointments for tomorrow, so I’m going to try to catch two cats. I have my remote control trap, because some of the cats are already fixed. And so, I’m going to selectively trap ones that haven’t been fixed yet. Then transfer it into the other trap so I can use the robo trap again.
[00:18:19] It has this. This battery is connected to a little switch that triggers this actuator, they use them for car doors.
[00:18:30] Griff Griffith: The setup Alison is using is advanced yet. Its design is elegantly simple. Imagine a cage trap that has remote control door triggered by a key fob like what you use to open your car door.
[00:18:41] Allison Fluty: have a little camera that I put out, and then I just kind of sit in my car. And these cats are, they’re not super shy, so I’ve been able to sit, like, right here while they’re eating right here to trap them.
[00:18:54] And then, so this is a Reolink camera and it uses um, a SIM card that I just buy data for.
[00:19:00] Griff Griffith: She aims the camera at the trap and can watch real time video on her phone. This allows her to sit in the car, using it like a blind , so as not to disturb the cats. The cat’s preferred food is set in the trap. if a new cat or a known cat that has not been caught before wanders in, she triggers the trap.
[00:19:15] Allison Fluty: So this is where a lot of the trapping Just Sitting, They’re coming out now, huh?
[00:19:21] My camera is lagging so now I
[00:19:24] can’t tell if the cat that’s going in there tipped or not?
[00:19:28] Griff Griffith: Tipping refers to whether the cat has a small portion of the tip of one of its ears surgically removed, which is a universal sign that this cat has been spayed or neutered. Allison doesn’t wanna re trap a cat that has already been fixed. She watches closely as the cats approach .
[00:19:41] Allison Fluty: Oh, there we go. tell who. I can’t tell who it is. oh, I do need that, that one. So one of the is going in the kitten’s, like probably months old. I’ll get this one Let’s get this ready.
[00:20:10] Griff Griffith: Allison covered the trap to keep the cat calm.
[00:20:13] Allison Fluty: And so, I’m going to transfer into this empty one. You’re okay. Oh, I’m sorry.
[00:20:21] Griff Griffith: Allison had prearranged two appointments in the next morning with a vet that aids in TNR efforts. .
[00:20:32] Appointments take time and cost money for an already overworked veterinary industry. When a vet sees a cat that has been trapped, there are several things that happen.
[00:20:42] Mike Armer: Cats are brought in in a specific type of cage. They are always scared, and they’re tend to be much more aggressive than pet cats. And so, uh, unfortunately we absolutely have to sedate every single one that comes in. And so we’ll sedate them, do an evaluation looking for, fleas and whatnot.
[00:21:02] do the, the neutering process. Um, depending on the exact details of the program, they’re usually given, vaccines, at least the rabies vaccine.
[00:21:12] The surgery depends on whether it’s a male or female. Male cats, are very easy to sterilize. It only takes five minutes. Female cats, it’s more complicated, more technically involved, and so it’s probably, depending on your experience, anywhere from 20 minutes to an hour. The whole process from presentation, to going home, probably a minimum of a couple of hours, but, most often it’s a bring the cat in, in the morning, pick it up in the evening type situation. After the neutering process, they get, uh, an ear crop, which is just a little notch out of the ear so that you can very easily from a distance, identify which ones have or have not been spayed or neutered.
[00:21:57] Allison Fluty: Through TNR, you’re also identifying cats that are friendly, and can be adopted, and so they are, you know, getting better lives I know some trappers have, found pets that had been lost for, two or three years and able to return them to their owners .
[00:22:12] , and if an area is, deemed to be too dangerous, for a cat to be returned to, for whatever reason, like if it’s Like a heavy construction site, or, if it’s, an ecologically sensitive area, that’s considered also, and, if it wouldn’t make sense to release the cat there, if or the cat’s going to have, too much of a negative impact on the area,
[00:22:36] , then that’s when they’ll also consider, you know, is this cat a candidate for like a barn cat or a garden cat program? There, there’s a lot more that goes into it than I think a lot of people are aware.
[00:22:48] Griff Griffith: But in light of a nationwide vet shortage, and since much of this work is volunteer driven and time consuming, it doesn’t scale well, but it certainly does work in targeted efforts. Of course, more public funds or donations to humane societies and TNR organizations would really help too.
[00:23:05] So far, we’ve been focused on the harm outdoor cats do to wild animals and how it impacts cat’s health as well. But did you know that outdoor cats can harm people and their owners too?
[00:23:19] Mike Armer: Toxoplasmosis is a parasite, and specifically it’s a protozoal parasite, and it’s pretty common. Cats are considered to be what’s called the definitive host, meaning that’s the host that the parasite can reproduce in and spread, but it actually can affect any warm blooded animal, so that includes humans.
[00:23:41] It is actually spread through the feces of the cat, so the outdoor cat, that’s infected defecates outside, it’s gonna go into the ground, other animals are gonna come along, be exposed to it, , and then it can infect those animals if, say, that was a mouse, and a, um, Wild animal comes along and eats that mouse.
[00:24:02] That other animal is going to most likely get infected as well, and it travels pretty much anywhere. It’s, in, it can spread by water and actually even go out into the ocean. Sea otters were very severely affected by it.
[00:24:15] Toxoplasmosis can cause a whole host of different symptoms. It can affect pretty much any part of the body, liver, intestines, lungs, kidneys, heart, skin, eyes. It even affects the central nervous system and can cause behavior changes in cats and humans as well, actually.
[00:24:35] Griff Griffith: In our Nature’s Archive podcast, episode 102 we discussed Toxoplasmosis with biologist Sophie Osborn as well.
[00:24:43] Sophie Osborn: A growing body of research is showing that the disease might be associated with a variety of mental disorders, including depression, bipolar disorders, schizophrenia, things like that.
[00:24:55] There was a study in Europe where women who had toxoplasmosis were twice as likely to commit suicide as women who didn’t have toxoplasmosis. So it’s seeming like it could be much more harmful to people than we initially realized. It also, in rats, makes them not fearful. It makes them bolder and braver.
[00:25:16] And we’re finding that it has that effect on other animals too. So a lot of animals including people that contract toxoplasmosis are more prone to having accidents and trauma.
[00:25:27] Mike Armer: Pregnant women are the highest risk because it affects the fetus. It can cause abortion or fetal death, but it can affect, you know, anything in the human just like it can in the cat. So one of the more common things in children is that it affects their eyes. can cause vision problems.
[00:25:43]
[00:25:44] Griff Griffith: As a conservationist, I’ve been so focused on how cats might harm the environment that I haven’t even considered toxoplasmosis. And this gets us to the main point. The best solution to the outdoor cat problem is prevention. If you have a new cat, please keep it inside.
[00:26:01] People might let their cats outside simply because that is what they grew up with and are used to, and they haven’t even considered the bigger picture.
[00:26:08] Others feel like letting cats outdoors is the only way to let the cat have a full enriching life. But is this true?
[00:26:14] Mike Armer: There are so, so many different things that you can do to enrich the indoor environment. There are tons of products you can buy. There are many websites devoted to ways you can do that without buying products, and in the end, when you’re spending time trying to make your cat’s life better, it becomes a better relationship with the cat. Absolutely, you can have cats that are completely satisfied and happy, strictly indoors.
[00:26:41] If you can train a cat to be on a leash, kudos to you. They seem to generally be happy and are much less likely to be getting injured, though not 100 percent risk free. are great for protecting wildlife, but they’re not necessarily going to prevent the cat from infectious diseases.
[00:27:01] But they allow the cat to go outdoors, smell the smells, see the sights, all that sort of thing.
[00:27:06] Allison Fluty: Sometimes simple things like just pushing a cat tree up against the window and putting up a, a bird feeder or, Playing with your cat is a of enrichment that’s also really, really important.
[00:27:17] You know, finding what your cat likes to play with. Um, some people will say, oh, my cat doesn’t like to play. There’s so many different toys, you can be creative, just find what, what’s enriching to your cat. You know, sometimes bringing something from outside indoors and letting the cat smell it, scent enrichment is another type of enrichment that exists.
[00:27:38]
[00:27:38] Griff Griffith: Scent enrichment, what a great idea. We tend to look at animals through a human perspective, but many animals rely much more on scent than we do, so give it a try. If you have windows, consider making a pedestal or placing a stand near the window so your cat can look outside.
[00:27:54] And move your cat tree or stand around from time to time to give the cats a new perspective. And just like with kids, periodically take toys away or reintroduce older toys. And of course, new and different shape boxes and bags and containers are perennial favorites.
[00:28:09] If you currently allow your cat outdoors, yes, it might be hard to retrain it to be indoors only. Try limiting the hours you let it out to the least impactful hours.
[00:28:18] And of course, make sure your cat is fixed. If you can’t afford the procedure, there may be organizations that can help.
[00:28:24] And speaking of trying to keep your cat indoors, did you know the bird migration is as predictable as the weather?
[00:28:29] In fact, there is an amazing resource called Bird Cast that shows anticipated migration volumes. So birds tend to migrate only on the best weather nights by keeping your cat indoor during those nights and the 24 hours that follow, you could give those migratory birds a chance. You can sign up to receive local migration alerts from BirdCast. Go to birdcast. info and search for Migration Tools or check our show notes.
[00:28:53] And there are other simple things you can do!
[00:28:56] If you have an outdoor cat today, make a pledge that your next cat will be an indoor cat.
[00:29:01] If you see a lot of outdoor cats in your neighborhood, seek out organizations like Bay Area Cats that come out and do TNR. .
[00:29:08] And remember, if you find kittens, there is only a narrow window in which they can be socialized for adoption. Eight weeks is typically the cutoff, so don’t delay.
[00:29:18] And perhaps you can educate your neighbors? Try online neighbor forums. And remember, most people don’t respond well to lecturing. Perhaps take an approach of, I just learned this and thought you’d like to know too.
[00:29:29]
[00:29:29] Griff Griffith: Unfortunately, progress has been slow or non existent in the overall outdoor cat problem, because too many people take an idealized point of view depending on whether they identify as a conservationist or as cat lovers.
[00:29:41] Allison Fluty: There’s the bird people that are very against the TNR, , and against outdoor cats , and then there’s the, cat people, , who feel, that the bird people are vilifying the cats and, just seems silly to me, you know, that , they kind of make each other out to, be , the villain, but really I’m like, we all kind of have the same, goal.
[00:30:05] We all want cats to be healthy. We all want a healthy environment. We don’t want to see, one animal suffering and the other one thriving. We want, them all to be, safe and healthy. My dream is to bring the birders and the cat people together to realize they’re on the same team.
[00:30:21] Griff Griffith: Sophie Osborn adds:
[00:30:23] Sophie Osborn: And so if each of us does one thing, if you can’t cope with having your cat indoors, maybe keep it in for five days when you think a nest might be hatching or fledging in your home.
[00:30:33] And if, 10 million people keep their cat inside for a week, that’s something more than nothing,
[00:30:40] Griff Griffith: Thankfully, I’ve seen that our listeners are open minded and open to the nuances that are inherent in nature.
[00:30:45] So let’s be part of the same team and help our cats and help biodiversity. In my case, Meow Meow and I moved several times, and I did my best to limit her hunting, but it wasn’t until she was like around 9 that we moved into a place with a tall fence that the killing stopped. And I knew that I’d get another cat someday.
[00:31:03] And I made a silent promise to the dozens, maybe hundreds of birds, lizards and snakes that Meow Meow killed, that my next cat would live indoors.
[00:31:11] Now I have two indoor cats named Mimi and Sister. With toys, cat trees, and a catio, their lives are as safe and stimulating as I can make them, and boy, are they cute. We sleep together every night and they still hunt. But now it’s laser lights and stuffed mice, and no one has to die.
[00:31:29] What did you think of today’s episode? We’d like to hear from you. You can email us at podcast at jumpstartnature. com or leave a comment on one of our social media pages. You can find us on Blue Sky , Facebook, and Instagram at jumpstartnature.
[00:31:46] And please share this episode with three of your friends or groups that you think would benefit from hearing it. A big thanks to Allison Fluty, Dr. Mike Armer and Sophie Osborn for their insights in today’s episode.
[00:31:58] Jumpstartnature. com slash cats has a transcript and full show notes , including links to topics we mentioned and additional resources to help you learn more about outdoor cats.
[00:32:08] Michael Hawk: Jumpstart Nature was created and is produced by me, Michael Hawk.
[00:32:12] Miles Ewell provided sound design and our host is Griff Griffith. Thanks for listening.
