Squirrel Treefrogs: Coming to a City Near You!

12/2/2025

Squirrel Treefrog | © Ty Smith

Building Ranges

Sometimes, things end up where they are not "supposed to be", and members of the newly named genus Dryophytes have a reputation. These frogs are well known hitchhikers, often showing up many miles away from home. These frogs can be found on greenhouse plants, pallets, lumber, bags of mulch and soil, pipes, campers, cars, and apparently even produce based on several recent reports. If there is a moist hiding spot, these frogs will use it. The issue is all of these hiding spots tend to be moved from time to time by humans. This means these frogs tend to end up places where they "shouldn't be", and records on maps look more like a bird's than a typical frog's. Let's compare the two maps from iNaturalist below.

Squirrel Treefrogs emerging from a pipe | © Robert Dobbs

Southern Leopard Frog (Lithobates sphenocephalus) observations from iNaturalist

Dunlin (Calidris alpina) observations from iNaturalist

Most reptile and amphibians follow a pattern similar to that of the Southern Leopard Frog. Notice how one can draw a line and all observations are behind that line. Anything to the one side of the line (right in the case of both maps above) is normal and predicted, anything on the other side is abnormal. This is usually evidence of a natural spread among these species. Now, we can note some clustering of observations; in this case these seem to be following areas of high human density. Of course on the fringes of the range, observations seem to spread out a bit, but that is because most species' density declines on the fringes. There are exceptions, but these are typically species that back up to a barrier like an ocean.

Now compare that to the map of the Dunlin. Notice one can draw a line that captures all of the clusters to the one side but there are several "one-off" observations. Dunlin, in Virginia, spend their winters on salt and brackish beaches and flats. These areas with high densities are also not focused around cities, meaning these are the places where Dunlin hang out in the winter. This can be predicted. So, what is up with the observations to the left of the line?

One of Ty's iNat observations of a vagrant Dunlin.

Well, birds fly. These birds are individuals that are migrating and end up off course or "knocked-down" by storms. All of these records appear to be from times of year that reflect migration and we can verify this with other sources. Sites like eBird have really helped us to understand what is happening and if you want to see more on the density and migration of Dunlin, check out their "Status and Trends" page here. Hold onto this thought for a second, and compare this to the maps I show later in this article.

Getting Squirrelly

Now, so far I have talked about Dryophytes as a whole, and yes various species do hitchhike and move around. That said the crown goes to the Squirrel Treefrog (Dryophytes squirrella) for the king (or queen) of showing up where they are not "supposed to be". Let's look at some maps for this species. Below are a couple range maps of the species from the first good sources I could find in a Google search.

Map from Virginia Herpetological Society

Map from PBS New Hampshire

Now, there are some slight differences with these maps, but for what they are, I think validate one another quite well. This species ranges from the southern coastal plain of Virginia, down to Florida and around the gulf coast to eastern Texas. Now, let's look at the 2015 observation map from iNaturalist. Also, if you want to explore these maps more, the photos are hyperlinked to the iNat observations as of that year for Squirrel Treefrogs.

Observation Map from iNaturalist

We can see that this map mostly agrees with the two maps above. Yes, there are several "one off" records outside of the line to mark the range boundary, but many are very close to the line. These close dots could be new sites still part of the known populations or just a factor of the map drawing process itself. There are several outliers though, all likely being transplants (we will come back to that). Are there issues with the range maps above based on this map? Yes, but they are minor. As someone who does a lot of range mapping, these maps are still very good maps. We expect to see one or two inaccuracies, and even dozens on a micro level as a map is just a model. My "rough line" has some inaccuracies as well from being overly simplistic.

Models are how we understand processes, but are never perfect. We are always striving to make them better.

Now compare this iNat map to the Southern Leopard Frog and Dunlin maps, and you will see what I mean when I say this map looks more like a bird's observation map than a typical frog's map.

Zooming into Virginia we see that there is very little data, but there is two outliers, both on the Eastern Shore. At the time, these went unnoticed. They were brushed off as hitchhikers, and I too would have said the same thing. All and all though, this species has too little data in the state to really make a claim on any range maps' accuracy. So, that was 10 years ago, what does the data look like 5 years ago?

Observation Map from iNaturalist

The two maps above are from 2020. At this point I think you can see what is concerning with these maps. Yes, the overall range map is a little more zoomed out making the squares for an observation larger, but if one looks at the Virginia map you can see a northward push on the lower peninsula and this was about the time we realized these frogs are introduced and established in Northampton Co. Now, the points directly outside of our line is not unusual in a map like this. Like I said earlier, maps are models and it is difficult to fine-tune a perfect map. That said, I think we can all see there are not just a few "one-off" cases any more in the southeastern states but there are hundreds. To the point that I am not sure "one offs" accurately describes many of these observations anymore.

I added a map showing Mississippi to Georgia to show how much the observations have shifted. Upon further inspections many of these sites do not look like what we expect to see with a few hitchhikers, but they look more like populations. Notice that many of the points that are "in range" are just as or more spread out than many observations just outside of the range. One could argue that they are just being reported more, but the area around Atlanta Georgia has a huge population and zero observations prior to 2015 and now there are dozens in 2020. The same can be said for Birmingham and Montgomery Alabama. There are also records up to northern New Jersey and the farthest north cluster is around D.C.

Squirrel Treefrogs from Cape Charles (2025) | © Robert Suppa

By this point, I had documented one in Prince Edward Co. Virginia and Evan and I had heard one in Roanoke Co., though that one was calling too irregularly to get audio. Both of these frogs were sites with campgrounds.

Squirrel Treefrog from Gwinnett Co., GA (2024) | © Chris Brown

2025 Data - Virginia

The 2025 map at the same level as the others has so many "out of range" sightings that at the same scale as the other maps tells us very little for each state involved. I am going to just focus on three states for this, as these are the three states where I am most at home. This is also Herping Virginia, so I feel focusing on the region is best. They all tell a similar story though in a different way.

Virginia has seen a steep incline of observations, and now a very large portion of these are outside of that original range map. Earlier in the year, some senior Virginia Herpetological Society members and I had a discussion on an observation on the Northern Neck. At the time there were only 2-3 observations, but since then, there is now six in the same area of the peninsula. On its own, this doesn't establish a firm case for a population establishment, but I believe there is likely a population there based on what we will see when we get to Maryland.

Another place to watch is Chincoteague. There are two records with photos and one audio record of chorusing. All of these were 2024-2025. This is a popular tourist destination, and these frogs are likely hitchhikers on vehicles.

Observation Map from iNaturalist

Squirrel Treefrog excerpt from "Atlas of Amphibians and Reptiles in Virginia" a.k.a. the 'Mitchell Atlas'. The whole PDF is linked in the map.

Quickly, I want to compare all of the Virgina maps to the maps from the 'Mitchell Atlas'. This map was published in 1999, and I would say falls in line with what we presumed in the range maps that I outlined at the beginning and the 2015 iNat maps. Brunswick Co. is a bit surprising to me, but I could see them being in that area of the county naturally or a quick hitchhiker from Emporia. Mitchell noted that more work should be done to find the northern and western extent of the species, and I wonder if part of the reason that he was so unsure was due to their spread (which may not have been evident at the time) or just lack of data. We can never go back and find the answer, as there is very little data from the time to truly base a solid range on. It is only because of citizen science that we have a decent amount of 2015 data, very good 2020, and amazing 2025 data.

2025 Data Maryland

Observation Map from iNaturalist

Squirrel Treefrog from Newtowne Neck State Park, MD (2025) | © Benji Beluga

This map is from the Western Shore of Maryland. The blue pins are 5 sites that Squirrel Treefrogs have been documented at as of 2025. In 2021, there was an observation of a juvenile. In July 2025, Benji Beluga documented several calling males at Newtowne Neck State Park, and noted that there were also individuals in the portajohns. This is pretty strong evidence of a population, though ideally others should verify. This site is across the Potomac from the Northern Neck of Virginia, leading me to think that they are quite possibly established there as well.

From what I can tell, Maryland is aware of individuals popping up, but I see no data on populations on their government or any other websites. I bring this up to say while many herpetologists and states note likely range expansions, it seems very little work is looking into it.

Other observations in the state of Maryland all appear to be "one-offs" for now. The only other cluster is around D.C. These though are much more spread-out and in places like front porches, grocery stores, and the like, suggesting they could have came in on plants and produce. That said, I see no reason they could not establish in D.C. with time. This species is really good at living on houses, and they can breed in puddles. Only time will tell.

2025 Data - North Carolina

North Carolina has a lot of good maps and I encourage you to look at several of these maps and compare them to these observation maps. The map from Herps of NC seems to suggest that Squirrel Treefrogs are established in Greensboro. I do see some iNat observations from the area, but I cannot say either way. That said, look at all of the western North Carolina records. These don't seem to me to be established populations, but neither did a lot of the 2015 "one-offs". I suspect central North Carolina is seeing some natural expansion of this species, perhaps aided or coupled with hitchhiking individuals as well.

Squirrel Treefrog Range Map form HerpsofNC.org

Observation Map from iNaturalist

As far as far northwest North Carolina, I am unsure why the Herps of NC map fizzles out shy of the Virginia border. I see this in some or a weird "pinch" at the border in the same area in older guides, and I presume it is from a lack of data at the time.

Fall Out

So, it seems to me that the Squirrel Treefrog is expanding its range quite quickly. Maybe some of the differences is more people observing or looking in places where there is little data. However, for major cities to see sudden bursts of observations of species that were not reported before, I suspect this is not the case. There is a cluster of Green Treefrog records from 2015 in Atlanta, GA but no Squirrel Treefrogs until 2020. This is evidence that observer numbers may not be the sole blame.

Green Treefrogs and Barking Treefrogs also seem to be spreading in Virginia, but I am not seeing it so dramatically and across their entire range like I am in Squirrel Treefrogs. Personally, it seems as if Squirrel Treefrogs are evolving to live alongside of humans in ways other frogs are not. I have found Squirrel Treefrogs in bath houses, door frames, porch lights, bee hotels, kiosk, and even mailboxes. I reworked our Herping Virginia range map for this species and that can be seen to the right.

Known and Predicted Range *Someone posted a record from the Grayson Highlands State Park campground literally three days after I reworked this map...*

So, why am I concerned? Squirrel Treefrogs are likely harmless. They overlap in historic range with nearly every frog they are coming into the range of now. I am not afraid of environmental collapse from this species. My concern is that something is allowing a species to spread in this fashion, and we don't know exactly why. Sure, they hitchhike, but this species has done so for decades and before the last decade and we didn't have evidence of expansion that I am aware of. Is climate change, human activity shifts, or something else to blame? Is it strictly just this species affected by this or are/will other species do the same?

Could this foreshadow other species' takeovers such as the Cuban Treefrog (Osteopilus septentrionalis) which also has over 100 "one-off" observations outside of their known invasive range in Florida? How does this impact the spread of diseases in frogs?

One more thing I want to point out is my use of "supposed to be". Sometimes we bring organisms to new places on purpose and then say, "That is not supposed to be here", which is fair. But if an organism evolves to use humans to get what it wants, this is evolution working in the way it is supposed to. Almost all species expand or shifts range over the course of their existence. Many species use larger species to move. So, why do we treat organisms using us to move different? Yes, Brown Rats for example have caused massive ecological damage nearly worldwide due to traveling on human ships, but is this unnatural?

German Cockroaches are gross, but are they an ecological nightmare? We as humans try to seperate ourselves from nature, yet we are still part of it. So, are Brown Rats and German Cockroaches desirable in America? No, but who is to really say they are "not supposed to be here". They wouldn't be here if it wasn't for us, but these species are just living their story like we are. I guess you could make the argument that people of European decent shouldn't be here and therefore these rats and roaches shouldn't be, but populations shift constantly. I am not going into great depths to try to answer if anything is "supposed to be" anywhere as that is philosophical and honestly, the answer is an opinion. It is based on the opinion holder's experience, morals, and ethics. I just don't think Squirrel Treefrogs should be vilified for using us to expand as their nature intends as it is far more natural than we treat it. We should look much more at the environmental impacts.

What Can You Do?

First, always check plants, pipes, lumber, pallets, etc. when you buy it for hitchhikers. This does not just mean frogs, but many invasive species spread on these types of materials such as the Spotted Lanternfly. Don't move any animals if possible. If you find a frog you believe to be a Squirrel Treefrog, submit your observation to iNaturalist and if it is in Virginia but not in a county listed in green on the map above (please do list records for Accomack and the Northern Neck though), add it to the Squirrel Treefrogs Far From Home project that I have started. If you are outside of Virginia, you can add it as well if it is clearly outside whatever resources that state provides. If you are unsure, DM me [@tysmith] on iNaturalist. Details such as how do you think it got there, what purpose does the building serve, are you close to a business that may be a "bus station" for these frogs can really help us out. I am just hoping to raise awareness and help build more information that may help us figure out what this species is actually doing.

Works Cited

INaturalist. iNaturalist. (n.d.). https://www.inaturalist.org/

Mitchell , J. (n.d.). Mitchell Atlas (1999). Virginia Herpetological Society. https://virginiaherpetologicalsociety.com/atlases/mitchell-atlas.pdf

Squirrel treefrog - hyla squirella - natureworks. New Hampshire PBS. (n.d.). https://nhpbs.org/natureworks/squirreltreefrog.htm

Squirrel Treefrog. Amphibians and Reptiles of North Carolina. (n.d.). https://herpsofnc.org/squirrel-treefrog/

Virginia Herpetological Society. (n.d.). https://www.virginiaherpetologicalsociety.com/amphibians/frogsandtoads/squirrel-treefrog/index.php