One of the most common questions I get is, "What can I do to better learn these species?". My advice is always to find a few good field guides, read them, and then challenge yourself. But not all field guides are made equally. I love "Peterson Field Guide to Reptiles and Amphibians of Eastern and Central North America". It is a fantastic resource; but at the same time it has some flaws. To be completely honest, no guide is or will ever be perfect. That is why our guide on the website is constantly being updated and edited. Science is always discovering new things, I am learning new stuff, and taxonomy is constantly changing. I may put a line of text in to highlight a "key trait" that is backed up in other guides, and then notice that several animals do not display this trait by reviewing the species on iNaturalist, or read a paper that completely destroys that line of thought. That is when I go back and make a note on the website, or change it to something less misleading. Back to the Peterson's Guide, this guide is a book, and not electronic like ours. The last time it was published (to my knowledge) was in 2016. This means the writers are not able to go through every month and add new species and purge outdated information. The other issue is range maps. Some of Peterson's maps are wrong, and its not the authors' faults, but its the papers/studies they are using are projected ranges. Projected ranges can be beneficial in a field guide, as it shows the reader what could be there, as we do not know all of the exact range boundaries of most species. That said, if you look at some iNat range maps, you will find the two rarely match-up... Now iNat range maps have their flaws too, mainly being if an expert isn't combing through these "out of place" observations, they can be misidentified, and therefore an incorrect mapping. Now, I promise I am not here to down all of these guides to build-up my own, that is far from what this is about. Every guide I mention today are excellent guides, and I recommend everyone to use them. Use them to fact-check each other; heck, even use them to fact-check me. I am just here to talk about how to use these guides to successfully get your answer.
Part of knowing how to use a guide involves knowing their limitations. We all can read a field guide word for word, and understand the wording, I don't have to teach you how to read. So, really this article is purely on how to use field marks, guide limitations, and understanding how/why guides are written the way they are. I am no expert or critic on writing field guides, I am just a guy that uses guides a lot, identifies a lot of herps, tries to educate others on herp ID, and I am working on a guide for a website. All of my critiques are straight from my experience, and what I have seen confuse readers, across not only Virginia, but across the US. I am not trying to bash any of these guides, in fact if I mention a guide in this article, it is because I recommend these guides for beginners and experts alike.
Don't use a Single Guide
Luckily for us in Virginia, we have a wealth of herp-focused resources. The Peterson's, Virginia Herpetological Society (VHS), Herping Virginia, and Department of Wildlife Recourses all have really nice guides to help you ID your herps. There are also some more niche guides that I love like "Snakes of Virginia" by Donald Linzey and Mike Clifford, and "Salamanders of the Southeast" by Joe Mitchell and Witt Gibbons. No one is paying me to promote or demote any of these guides (I don't even get paid for my own guide), I am just giving my full opinion of these guides from a herpetology perspective. If you are in a different state, the Peterson's is still good for you, but nose around online and try to find another recourse. Most state Fish and Wildlife branches and herp societies will have, at worst, decent guides.
I say always use multiple guides because the two biggest flaws I see in all guides is wording and lack of description in figures (we will get into figures later). As scientists, we never like to say "always". Even when talking about gravity, we do not say, "The apple will always fall." but rather, "The apple will fall." or "The apple will probably fall." Scientific journals are rather "matter-of-fact", and this carries over into field guides. This is great for people like me that love to baste in the knowledge, but I understand not everyone cares for this style and many have a hard time understanding it. This is part of the reason I try to (for lack of a better term) "dumb-it-down" in my guides. Honestly, scale counts are almost never necessary to identify snakes here in Virginia, so why drone on about scale counts to someone who is only curious. If you are like me though and enjoy that stuff, VHS is your bread and butter.
We only care about this speck because similar species like Pickerel Frogs, Kauffeld's Leopard Frogs, and Green Frogs should lack this speck all together. So, how can we use this trait? Simply put, if the subject has a speck on the tympanum, it's probably a Southern Leopard Frog. This is why I have worded it as such in our guide, "The Southern Leopard is our only True Frog species that can have a silvery speck in the center of the tympanum."
This is all to segwue into something I think all field guides need to do a better job at and that is defining "key traits" vs "average traits". Both of these are "field marks, but key traits should be a feature a species has that distinguishes it from other species nearly 100% of the time. Average traits, should be traits expressed by a majority of a species, but not nearly 100% of the time. For example, and average trait for humans is, "Humans usually have brown or black hair." This is true. A majority of the human population has brown or black hair, but its far from 100%. while a key trait would be, "Humans lack dense fur that covers the whole body." This is also true, as almost all humans do lack this hair that similar species such as Chimpanzees have, except for rare occasions caused by syndromes such as Hypertrichosis. Though there are exceptions, this fact applies to well over 99% of the population, therefore it can be classes as a key trait. Peterson's Guides do a great job pointing out key traits, but many they point out are averages. If we say stuff like, "This species on average..." or "This species has..." more effectively as guide writers, we can get this information across much better to readers. This is why a reader should rely on back-ups to better understand the traits listed.
Examples of these Traits
Bellow are some traits for species that often confuse people. Do you know which traits are average and which ones are key traits. Average traits are only good situationally, but can also be completely useless.
Use a Holistic, "Sum-of-its-Traits" Approach
Genetics are complicated, and even key traits can be wrong on a rare occasion. Hybrids, "throw-backs", and random "genetic hiccups" can make an animal's express genes that do not reflect its species. We all know what a hybrid is, but we probably all learned in school hybrids were sterile and/or weak. Well, in many cases yes. Ligers (male Lion x female Tiger) are sterile and too large, and docile to survive in the wild. Mules (Domestic Horse x Donkey) are sterile except for rare instances where the "stars align"... But for many animals, this is not the case. One example is our Coyotes in Virginia are only about 70% true Coyote and the rest of their genes are of Gray Wolves and Domestic Dogs. Any combination of the three was once though to be a "weak cross", and wouldn't fair as well in nature as their non-hybrid counter parts. Well, now we see that these animals survive and do better than any of their "natural" (for lack of a better word) ancestors and have dominated places where the others couldn't.
Many of our herp species are so closely related, that they form populations of hybrids along their boundaries with sister species. We refer to these as "intergrades". These intergrades can have an evolutionary path from their parent species all of their own, becoming another species as well. We see this with Dusky Salamander species in Pryon's paper that I have another article about, so I won't dive into it all here. But, hybrids are often carrying genes of both parent species, so when they breed back to one of their parent species, we see a lineage of offspring that have these genes that are often "turned-off". Sometimes randomly, these genes get "turned-on" and you see a feature in an animals that should be in its sister species.
When two species split, some genes get locked away in one species, and continue in another. Sometimes, the genes that are locked away get "unlocked" and an individual will express genes that that species does not normally display. I mentioned Hypertrichosis earlier, and that is a great example of this, as modern Humans lack course body hair that covers the body, but our ancestors do. We refer to these as "throw-backs", as these are traits that reemerge after many generations of lying dormant (kind of like when a song from the 70's pops up in a new movie).
I used the term "genetic hiccups" above as well, so let's define that too. By "hiccup" I mean an accident. So, sometimes there is a mistake while genes are being copied, or mutations. This can lead to disorders and syndromes, or be completely benevolent. We think of mutations as bad, but this is not always the case. Mutations are the cogs on which the machine of evolution runs. Every living organism has a mutation. Somewhere in you lies a gene that was copied wrong and it is not necessarily a bad thing. Some of these "mistakes" affect nothing, others are so drastic that the organism dies as a fetus. I say all of this and go so deep to tell you: some of these simply change species colors, patterns, of body structure.
So, I just told you several reasons a key trait could be wrong, but how do you know if something is amiss? Well, let's use a rough analogy: You would probably know your mother (or Grandmother or any other woman in your life), seeing her from behind just based off of her hair. Now, if I wore a wig that looked just like your mother's hair, how would you know I am not your mother? Well, I am a portly, burley-looking, bearded man for starters. We are not as dim-whited as Little Red Riding Hood, and cannot distinguish a wolf from our Granny because of a pair of glasses, because at the end of the day, the wolf still had big eyes, a big nose, a bushy tail, and big teeth.
See where I am getting? We can use a sum of an individuals traits to get a better idea of what an animal is. The same way you would look at me and say, "You ain't my Mama, cuz my Mama is not a MAN!", you can say in the case of my Georgia Southern Leopard Frog example above, "Yes they have Kauffeld's Leopard-type patterns, but they have long snouts and are far out of the known range of Kauffeld's Leopard Frogs."
Using one, singular trait to base an identification should only be done when there is no other option (i.e. a bad photo/angle). There is some rare exceptions though, like the mentioned femoral reticulum of Virginia Leopard Frogs, calls from Gray Treefrogs, and range maps on Mountain Duskies. It is best to read your guides enough to know these super similar species so you know what you need to refence when the time comes.
Read the Text, Then look at the Figures
Remember towards the beginning, when I said, "The two biggest flaws I see in all guides is wording and lack of description in figures (we will get into figures later)." Well, its finally later... A "figure" is a diagram that points out what is being explained. This can be a sketch, a graph, or a photo that points out what is attempted to be conveyed. Here are examples below:
Figures are great. They are an excellent way to convey traits that are frankly hard to explain. Now, I am using Virginia Herpetological Society's figures a lot of examples of this, because they are online and easy to access. I am not promoting them nor am I bashing them. I used them in three examples of good figures, and I hate to do this, but here is an example of a bad figure as it has no context to connect it back to the text.
Now, what makes this more useless is that the Broadhead can also have four supralabials. In fact, VHS says, “labial scales between rostral and first supralabial entering eye (= preorbital supralabials) 5/5 (53.1%, n = 49), 4/5 (34.7%), or 4/4 (12.2%).” Now this one I’m not as sure about… I have IDed over 1,500 Broadhead Skinks on iNaturalist, and I only can think of a small handful that displayed four supralabials, but then again, I’m not exactly counting supralabials. But this says nearly 50% of Broadhead Skinks have four supralabials on one or both sides… I have never seen this number in any paper that I recall, but I do recall numbers like 95%-97% have 5/5. I’m not hear to argue numbers though, my point is this: if only 50% of species “A” have this trait, and 80% of species “B” have this other trait, but the other 50% and 20% have each other’s trait, why even make a figure that is useless to ID the two? You may say, well 70% or 80% is an overwhelming majority. That is true, but 90% of the world's population has brown or black hair. So, you are more likely to find a skink with an off labial count than to run into a blonde. VHS, or whoever created this figure has beautiful head shots, which display postlabials and even the clear difference in head depth, why focus on the thing that does no good to ID them? And then there is no context, which makes people think this is the way to distinguish between the two. This is a big mistake, and VHS isn’t the only one who has/will make it.
All and all though, VHS is great. If this is the biggest flaw I can find with their guide, than it is not bad at all. But this is why it is important to read the information and not just look at the figures; and once again, look at multiple guides. As I mentioned, I don’t like being critical of these guides, but it’s necessary for us to see what we did wrong in order to grow from them. By all means our Herp Guide at Herping Virginia isn’t perfect (or complete for that matter), but these are the issues I am trying to avoid.
Now, let’s talk about maps. Range maps are often a mix of known areas and projected areas based on these known areas. We are getting better at mapping species to better understand true range boundaries, but others are not so well understood. Each guide has several mapping systems, all having their pros and cons. VHS maps are based on reports to VHS and use a county system. This means if that species has been documented in a county, the whole county lights up (even if it is found only at one site on the edge of the county). The down side to this being, you cannot see where a species may be found, but hopefully we can close these maps up and make them more accurate, and unfortunately I think their maps are not being updated with taxon changes. Something is off with a few of them. For example, their maps show the Northern Slimy in Cumberland, Chesapeake, Amherst, Nelson, and several other counties where we know based on genetics that this species never existed nor exist now. I’m am not sure what is the deal with these, either they are not being fact-checked properly or what I suspect is these reports were made before the White-spotted and Atlantic Coast Slimies were described as all were formerly Plethodon glutinosus, which now only applies to the Northern Slimy. I see similar issues with the Northern and Southern Ringneck Snakes. So, as much as I use VHS maps, remember, most of these maps are likely 100% accurate.
Below are several examples of maps for the Southern Ringneck Snake.
Both maps above are from Virginia Herpetological Society. The map on the right (while not perfect) is a much better representation of the subspecies ranges than the reports map on the left.
Peterson’s uses predictions based on scientific papers, and this is pretty good for the big picture. Unfortunately, when you look at individual states it can be hard to tell where things start and stop, and that state may have out dated information they provide, making the map off in that state. These newer studies are fairly good at using genetics to build maps. To explain it simply, these species that exclude one another tend to intergrade along boundaries. Using genetics you can pretty much see if any interbreeding has happened. This means you can follow geographic boundaries to find range boundaries and not guess based on several, minor factors. I mentioned the Ringneck Snakes above, and at least for Virginia, Peterson’s knocks it out of the park. That said, there is other maps that probably over predict, and some that don’t expand enough.
Now, at Herping Virginia, we use iNaturalist maps. Are they better? In situations… but worse in some other situations… First, let’s explain how this works. People report observations, and naturalist-minded folks ID them. Unfortunately, this could be a botanist IDing your Herps, and they may not exactly know what their looking at. There is also a saying, “The more you know, the more you find that you don’t know.” Well, I like to say the opposite is true too; “The less you know, the less that you find you don’t know.” In other words, armatures get on there IDing away with their fancy “key traits”, parroting lines from their field guide, and what they don’t know is they are using a 1980’s print of a guide and talking on a species that has been split in the 2000’s. Your out dated guide will never help you ID a species that wasn’t described until decades later. Anyways, that’s why a lot of your experts ban together to get these IDs straight, as we are building these maps. It’s great. The experts always win out on IDs, so everything should be IDed properly. Except for the fact that we cannot keep up with the constant flow of misidentified Herps. So, a few times a month I will pick a handful of species and “purge” (I go in and correct as much as possible for hours, usually until I run out of that targeted group). Usually I’m correcting toads from Virginia Beach that are ID as Americans, but they are obviously Southerns, Skinks, Cooters, Sliders, Duskies, you name it, I have purged it multiple times. There was a time that I had IDed every Virginia herp observation on iNaturalist, but then the Herps of Virginia project caught on, and in about a year we went from ~21,000 observations to ~73,000… It took me 3 years to ID the first 21,000… And remember too, not all of our experts of Virginia residents, and they tag me in stuff too, and I see mistakes in the Carolinas, Florida, Maryland, etc. So, I am pulled in every direction trying to clean-up as much as possible, as is every other expert on the platform. All of this to say: iNat maps are not perfect. Be skeptical of outlying observations; but luckily, if you see one of these you can explore it yourself. Is it really what they are reporting it as? Is it a captive animal? Did they give the correct location? You can click on the observations and see for yourself.
Now guides are great resources, but it is pretty nice to check your guide against actual papers that come out. This way you know your guides’ limitations. For example a new paper came out in 2021 redescrbiing the Eastern, Gray, and Western Ratsnakes to now the Yellow, Central, and Western Ratsnakes. If you are in the southeast and break out your Peterson’s on a Yellow Ratsnake it is no longer P. alleghaniensis but now P. quadrivitratus. Now, iNaturalist hasn’t caught up to these changes yet either, but this is something that will be important to know for life listing, range building, and education. Once again, I’m am not attacking the Peterson’s Guide, as the latest edition was 2016. It seems all guides are outdated almost as soon as they come out. What I wrote here today may be outdated by the time you read this. With the time it takes to publish and update, they cannot make a new edition every year, and in that time publishing and printing, something else would change that would throw it right back out-of-date. I suggest if you have a supposed ID, check and see if there are any recent papers on that species to see if that species still is recognized and hasn’t been split.
I also like checking the “average traits” in these papers too. VHS does a good job at providing this on their species pages, at least for scale counts. I feel like I haven't been positive enough on VHS in this, they do great work and I have used them for bad examples a lot in this because they are so easy to access. Reading a VHS species page is pretty close to reading a scientific paper. Take their Eastern Kingsnake page for example. VHS says under "Scutellation", "dorsal scales smooth, scale rows usually 21 (89.9%, n = 79) at midbody, or maybe 20,22, or 23 (10.1%)." VHS literally shows the percentages of specimens the studies that they reference that expressed these scale counts. This is extremely valuable information an it is well done by VHS. Are scale row counts going to be useful for you to identify an Eastern Kingsnake? Probably not, I just chose a random species for this example, but maybe some crazy scenario will come up and it will be useful. This kind of information is spectacular on other species though like Skinks.
Check Yourself Against Experts
Finally, how do you know you are right? Some adjectives for key traits are rather subjective, and though they make perfect sense to an expert that has seen the species several times, do you understand the meaning. These can be descriptions such as "a clean line", "a prominent spot", or "a lighter colored ____". For example, "a prominent spot in the tympanum" for a Southern Leopard doesn't mean Kauffeld's ever have a spot, its just never the the bright silver/white as with several Southern Leopards. Just because you notice a spot, doesn't mean its a prominent spot, and it is all relative to the other species at which you are comparing the animal to. So, how do you check your own understanding? Ask questions.
Personally, I feel there is no excuse to be herping and not reporting your findings somewhere. I strongly suggest you report herps to iNaturalist, Herp Mapper, Virginia Herpetological Society, or anyone else taking in citizen science data. What I love about iNaturalist though, is I can have someone else check my observations and correct me if I am wrong. I strongly recommend you do this as well. Use your observations as a learning experience. Say, "I think this is a _____ because of ____." That way someone can guide you to the right direction.
I strongly discourage you from posting to a Facebook group for an ID. You will get the right answer, among a dozen wrong ones and then it is up to you to pick it out. Sometimes, someone on iNat will misID something, but it is never the three-ring-circus Facebook is... Other routes include VHS answers emails and we at Herping Virginia have a form you can submit photos to for us to ID. Its pretty painless. I'll throw a button with the link below.
Getting This Over With
Oh, boy... I hate running an article so long... I know it is not as fun to read, nor is it fun to write, but I feel this is all valuable information. I hope you see that all of the guides I mentioned today are great guides, but none are perfect (not even the one I run). If you want to become more knowledgeable, read all of these guides. Just remember, the best way to catch mistakes is to compare species pages to pages in other guides. I have linked VHS bellow, and I will even put a button for each hard-copy field guide I mentioned, so you can find them for purchase. If you have any questions, as always you can contact us using any method you see in the website footer.
Kleopfer, J. D., & Hobson, C. S. (2021). A guide to the frogs and toads of Virginia (Vol. 2). Virginia Dept. of Game and Inland Fisheries.
Powell, R., Conant, R., & Collins, J. T. (2016). Peterson Field Guide to Reptiles and Amphibians of Eastern and Central North America. Houghton Mifflin.
Virginia Herpetological Society. (2022). Virginia Herpetological Society. Retrieved December 10, 2022, from https://www.virginiaherpetologicalsociety.com/
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