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Birds and Their Houses: Cavity Nesters in Florida

Birds come in all shapes, sizes, and colors. They play a critical role in our ecosystems, keeping insect populations in-check, serving as a valuable prey item for our larger mammals, and helping to disperse seeds! Just like people, birds need food, water and shelter to survive. In this episode, we will explore a special type of bird called cavity nesters, who, as the name implies, need cavities to nest, reproduce and thrive.

Episode Transcript:

SHANNON:
In today's episode, we'll be talking about different species of cavity nesting birds in Florida. We will also talk about habitat and what they might look for in an artificial nest box.

LARA:
Welcome to “Naturally Florida,” a podcast about Florida's natural areas and the wild things that live here. I'm Lara Milligan.

SHANNON:
And I'm Shannon Carnevale.

LARA:
This podcast is brought to you by UF/IFAS Extension in Polk and Pinellas Counties.

SHANNON:
So what we're going to be talking about today are different groups of birds. There are thought to be as many as 10,000 species of birds worldwide. And that's a really difficult number to grasp for most people. So it helps to group them, right?

LARA:
Yeah. And especially group them in like nonscientific language. (LAUGHS) In general, you might hear people refer to birds as like, oh, those are shorebirds or those are songbirds or birds of prey or waterfowl. And so those are ways that we can kind of broadly classify birds. And within that— you know, we don't want to get too far into that—but like obviously shorebirds, guess where you're going to find shorebirds? (LAUGHS)

SHANNON:
(LAUGHS) Let me guess.

LARA:
Yeah.

SHANNON:
Maybe on the beach.

LARA:
Ding, ding, ding! And like I said, today we're going to be focusing in on different ways that birds nest. And within that, Shannon and I were looking at this really cool graphic online that shows the different ways and areas that birds can nest.

And so, right, some birds might nest on the ground. Maybe people didn't know that. That might seem like counterintuitive—like, well, that seems like a horrible idea. There's reasons and ways that that works for them. Platform nesters—most people might think of like ospreys for that because we do provide a lot of artificial platforms for them. Ledge and cliff nesting—which we don't really have a ton of cliffs here in Florida. (LAUGHS)

SHANNON:
We don't. But we do have a lot of skyscrapers and that's where pigeons like to nest.

LARA:
Yeah. Birds have definitely learned to adapt to the urbanizing world, which is actually part of the reason we're doing this episode. Which brings us to this next group we're going to be talking about today, which is cavity nesters.

SHANNON:
Yes. And cavity nesters are broken down into two groups also. So we have primary cavity nesters, which are species that are capable of excavating out their own hole or cavity. And then we also have secondary cavity nesters, which are species that use a hole that's already existing. So it could be a rotten out tree trunk, or it could be a cavity that a primary cavity nester isn't using anymore.

LARA:
Yeah. And I actually got to witness that firsthand at the preserve where I work at. We got to watch some pileated woodpeckers excavate their own nest, which then after they left, it got occupied by an eastern screech owl. It was like the coolest thing ever.

SHANNON:
Okay. I think this is a great time to share with everyone the sounds of a pileated woodpecker excavating its own cavity.

(WOODPECKER POUNDING)

Okay. Thanks. Now, what were you saying?

LARA:
That kind of highlights what I wanted to touch on, which is woodpeckers are considered primary cavity nesters. They are totally built, tip of the beak down to the tail, to peck out some wood and create their own cavities. Even nuthatches and chickadees are considered primary cavity nesters.

And then pretty much all the other species on my list would be considered secondary.
So thats, I already mentioned the eastern screech owl. We have the barn owl, the barred owl—so of our owl species those will occupy cavities. Even vultures, turkey and black vultures, fall into that category.

SHANNON:
What?!

LARA:
I know, right? It's crazy. These, like, massive birds as cavity nesters. And then all the way down to, like, our Carolina wrens. Super cute! The chimney swifts, which I'm sure we'll talk about a little bit more later.

We have a ton of the eastern bluebirds in my neck of the woods. Flycatchers. And then there's a variety of duck species as well—the wood ducks, the hooded mergansers. So, yeah, just a variety of other secondary cavity nester species, of which we have 25 species total in Florida.

SHANNON:
Wow, Lara! That's a lot of species. Knowing that they're all cavity nesters, do they all use their nests year round? Or is this more of a seasonal thing?

LARA:
Yeah, that's a great question. So for most of the cavity nesters, we would say that it's only when they're nesting, it's when they're going to be using the cavities that we provide for them or natural cavities. And generally speaking, that's like March through June. Again, species to species there's some variation there. And on occasion, and generally from what I've found in the research, is owls are more likely to use them as roosting sites year round—but it's not always.

So if you’re, like, hoping to build one of these boxes to have like a bird nearby all the time, I guess I'm here to tell you that that's probably not going to happen. (LAUGHS) You might get some other species in there, but you won't have the ones that you're trying to attract year round.

SHANNON:
Yeah. Yeah, we get that a lot here at the Extension office. We’ll get calls all the time about, “Hey, there's a squirrel in my bird house. Why is this?”

LARA:
Yeah. I get questions like that all the time. It's usually squirrels and usually related to bird feeders, but they will also take advantage of bird houses as well. And I was actually just reading up on research through NestWatch, which is from the Cornell Lab of Ornithology. They do like all things birds. I go to Cornell and they actually did show that there is correlation with putting on these different barriers.

Like if your nest box is on a pole, you might see like these little cone-shaped things, or sometimes it looks like a little stovepipe. And there's even something called the entrance extender. It's just like a block that sits in front of the hole, that just has been shown to decrease the chances that predators and other species will get in there.

But yeah, you're pretty much going to have somebody else in there one way or another, but they are proven to help a little bit.

SHANNON:
Yeah, it sounds like real estate here. The housing market is hot.

LARA:
(LAUGHS) Yeah. And I mean that’s, again, the reason we're doing this episode is we've taken away a lot of natural habitat. And so anything we can do to provide habitat for these species is, you know, it's beneficial for the birds and then anybody else who might occupy. And actually one study that I was looking at specifically with the eastern screech owl, they found following species using their nest once they were done doing their business.

So other species of birds. So the great crested flycatcher. Super cute bird—if you're not familiar, check it out. Flying squirrels. Hello— Does it get any cuter than that? Gray squirrels. I don't know. Some people have love-hate relationships with them. Tufted titmice—one of my favorite birds because they have big eyes and they're really cute. And yellow rat snakes, which I'm sure most people aren't super excited about, but I think that's super cool. So…

SHANNON:
Same.

LARA:
(LAUGHS) Just a fair warning. You will be benefiting multiple species with these boxes.

SHANNON:
Yeah. It's just like whenever we recommend that people plant native plant species to support our wildlife, you're not always going to attract the exact species you're trying to bring to your yard. Any time you provide those something in that pillar of habitat—the food cover or water and shelter—you're going to attract a variety of wildlife. And it's the same thing with cavities. So I think that's pretty cool.

LARA:
Yeah. And I think the other important thing to mention is, you know, we talked about the primary and secondary cavity nesters. And we like to stress, like, just because you build doesn't mean that they're going to come. And so for a species like our primary cavity nesters the woodpeckers, they have the ability to excavate their own nest sites.

They're just not as likely to take up one that we're going to provide for them. They'd much rather be like, “I made this. I'm going to, you know, take advantage of my hard work.” And other species like chimney swifts, they're just so, like, specialized that we can't really just provide like a standard birdhouse, even if we get the right dimensions and everything for them.

There's actually some very specialized, I guess, habitat that you can create for them. And I know Shannon was showing some of the really cool designs with me so that you can attract them. It just might take a little bit more effort if you want to go that far.

SHANNON:
They do take a lot of special housing. If you want to try and attract chimney swifts, essentially you need to build them their own chimney, and it needs to be freestanding. And tall. (LAUGHTER) So it's a big deal.

LARA:
Yeah. And I would say if you're like, “I don't want to build a house and I don't even want to go buy a house,” you could still benefit these cavity nesters if you have a dead or dying tree in your yard. We call those “snags.” It's basically just a standing dead tree. Something, even if you had to cut down a tree and you can leave it like 15 feet high, that's going to be super beneficial not only for a variety of insects and things that are going to come in to decompose that wood, but potential cavity nesters might take advantage of that as well.

SHANNON:
Lara, thanks so much for mentioning snags. There are a couple of things I think we need to share. So the first is we completely understand snags are potentially dangerous to your family and your home or your structure. So we don't want you to leave a 40-foot snag right next to your house or playground, especially in Florida with hurricane season.

But like Lara said, you can cut off the top of it and leave a shorter snag and still provide a lot of those benefits. Also, you could leave a snag in a corner of your yard where it's not nearby children, playgrounds or your back porch. That's something I get a lot of questions about: “How can I leave a snag?”

Because people understand all the benefits they bring, but they want to make sure they're safe. And so one thing that I find really interesting is that a snag or a dead tree, even in Florida's humid environment, will stay standing a lot longer than people think it will.

So if a tree dies for, you know, it didn't get hit by a car. Like if a tree just dies and say you cut off the top of it and you leave 15 feet or so, it could stay standing for, you know, ten or more years, completely stable. But if you ever notice it starting to lean or it's swaying in the wind, I mean, definitely cut it down. But you would have then provided extra habitat for just a couple more years. And that can be really valuable to our local species.
LARA:
For sure. So, yeah, and that actually, as you were talking about snags, I was thinking about these artificial nest boxes. And I often see a lot of them installed right on a pole, right? So like the manmade version of a snag, which is a great option if you're able to install a pole and then affix your nest box to that.

But there is a lot to consider before, just it’s not just like put it up and they'll come, right? And it's not one size fits all. Birds are super particular about all the things when it comes to nest boxes, just like people right? We all have our preferences for our home. And so the same applies. First and foremost is like, where the heck are you going to attach this thing? How are you going to attach it?

And with attaching things you want it to be secure. And then just mentioned hurricane season in Florida. We definitely don't want to be installing something that's going to just get blown over or fall down because you didn't secure it. There are different height requirements, too, based on species.

And so what we're going to do is we have a blog that we're going to link in our show notes that has all the details for the particular species. ‘Cause (A) if we tell them to you here, you're going to forget and (B) It's just a lot to get into.

SHANNON:
Just so many.

LARA:
Yeah. So just keep in mind, the height requirement is something to consider as well as actually the orientation. So, right, it’s really hot in Florida. Pretty much it's like “don't face it west” is kind of like a catchall. Some species aren't super picky, but in general, like, if you can not create a little sauna for these birds, that would be awesome.

Now, I hate cleaning my house, but right, we got to do it. Same applies to nest boxes. And in order to do that, we want to make it as easy as possible. So we always try and stress for the bird house is to have doors with hinges so you can just open it right up, clean it out and you're done. You don't have to like disassemble the whole box.

And one other thing I want to mention is drainage. So in Florida, we have a lot of rain, right? We have a rainy season. And so it's important not only to have holes in the bottom of your nest box to allow any water that does get in there to drain out. But most designs actually have the floor like somewhat elevated above where it attaches to the front and the sides so that if rainwater drips down to the bottom and it goes up, it's not going to reach the floor.

And that's also why you see a lot of roofs overhanging, because that way, again, if the water drips over the edge, it's not going to go directly into the box.

SHANNON:
Yeah. And, Lara, you mentioned how the floor is attached to the sides and the walls. Just for your own sanity, you're going to want to use good fasteners. And what I mean by fasteners are screws and nails. So we have very harsh weather and a humid climate, and that moisture makes it really challenging for metal fasteners. So you want to make sure, at minimum, that you are using galvanized nails for your nest box if you're building it yourself.

Even better, if you want to use deck screws or some other exterior grade screws, the spiraling on the screw will hold on to the wood even as it shrinks and swells with the temperature and humidity. So always use really good fasteners if you're building it yourself.

Something we also get questions about are, is painting. “Can the kids paint the nest box or the bird house?” “Can we make it cute, or do they like a particular color?” In general, we recommend natural, unpainted wood options for your nest box. There seems to be preference among the birds for that more natural option.

Another question we regularly get with people who are building their own is “Should we put a perch on?” “Will the birds like to sit on a little perch outside of their house?” They are not needed in your nest boxes, and they are actually not recommended for cavity nesters. If you think of a natural hole in a tree or a natural cavity, there's often not going to be a perch there. And so by adding a perch you might actually be making that nest box more inhabitable by a predator or a non-native or invasive bird species as well.

LARA:
Yeah. Yeah. And I mean, when you think of perches and if you see them, it's often associated with a bird feeder, which obviously birds, like, do need that to access the food. So but in the case of this, we do not really want perches on our nest boxes. And one other thing I forgot to mention when talking about the drain hole is for the rain.

We also want holes at the top because, like I mentioned, it's really hot in Florida. Hot air rises, right? We need a place for that air to escape. And so usually most box plans that you'll see have holes towards the roof, like just underneath the roof, those side panels or the front panels where hot air can escape.

And one thing that you might often hear is to have untreated wood to use for building your nest boxes because of potential exposure to toxins that are used and the treatment of pressure-treated wood. As far as I can tell from the research I've done, there's not actually been any research to show that pressure-treated wood is causing harm to birds.

But we implement the precautionary principle here is, like, let's just not do that. So we do recommend untreated wood for your bird houses. So that's a lot that Shannon and I just covered. There's a lot to consider. And we don't bring this up like just for the sake of talking. It's like these are real things that you need to consider.
We want you to if you're going to go down this road of providing shelter and habitat for these birds—which is needed—we just want to make sure that you do it right and hopefully increase your chances of success. And not getting, you know, nest boxes that fall apart.

SHANNON:
Right. Or nest boxes that just never see a bird. (LAUGHTER) I can't tell you…I mean, this is more specific to bats, but they are also very picky. And I get so many sad phone calls about “Oh, I've had my bat house up for three or four years and I've never seen a bat use it.” We get the same calls about bird houses.

They're like, “Oh, I bought this bird house at Home Depot or Lowe's (or their neighborhood garden center), and I've never seen a bird in it.” And just like Lara said, it's because of how picky they are. (LAUGHTER)

So if you're going to go through this, please consider these. Check our blog post, look for resources specific to the species you're trying to attract. And it's really just so that you have a better success rate.

LARA:
Yeah. And it's not like, you know, the birds are finding these by chance. It's not like us where we have Zillow and we can go see what house is for sale or anything like that. So it takes time. And then I mentioned earlier the nesting season in general is like March to June. And so you ideally want to have these totally up and installed, like no later than February in the South is generally what we say. You want these up so that when birds are seeking these cavities, that they're there and they're available.

So if you're installing like in the summer, like late summer, you're probably going to have to wait till the next nesting season before you even have a chance of attracting somebody. So patience is key here.

SHANNON:
Yes. You're playing the long game. You’re providing that housing so in hopes that next season they find it.

LARA:
Yeah. And if nothing else, again, if you're like “I’m out! Too much for me!” you can always provide for cavity nesters and a variety of other local wildlife by planting native plants in your yard. Or you can help simply by reducing the amount of pesticides or herbicides that you use. So there's tons of ways that we can support birds big and small and a number of other species without installing artificial nest boxes.

So just keep that in mind, and thanks for listening. If you made it this far and you're like “No way!” (LAUGHTER) maybe share it with a friend who might consider doing that. But we would love to support you in any way that we can. If you're planning to go down this route again, we'll have a blog post if you want to go back and reference that way.

SHANNON:
Thanks for listening to “Naturally Florida,” a podcast about Florida's natural areas and the wild things that live here. Stay updated on new episodes by subscribing on your favorite podcast platform. If you enjoyed today's episode, consider sharing it with a friend. “Naturally Florida” is produced by your hosts Shannon Carnevale

LARA:
And Lara Milligan.

SHANNON:
If you have questions or suggestions, submit them online at naturallyflorirdapodcast.com. This podcast is brought to you by the University of Florida's Institute of Food and Agricultural Sciences Extension, an Equal Opportunity Institution. Thank you for listening.

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