Why Evolution is True is a blog written by Jerry Coyne, centered on evolution and biology but also dealing with diverse topics like politics, culture, and cats.
Sunday, May 2: What are Amphibians?
Monday, May 3: The Secret Lives of Amphibians
Tuesday, May 4: Amazing Amphibian Facts
Wednesday, May 5: Threats to Amphibians
Thursday, May 6: Amphibian Tweets from the Field
Friday, May 7: Partnering for Amphibian Conservation
Saturday, May 8: Actions for Amphibians
I began my Amphibian Week by hearing for the first time this year the trilling call of American Toads (Bufo americanus) yesterday afternoon, and I heard them again this morning. They were on my campus at the University of Wisconsin-Parkside, but not at the pond I was visiting, but I didn’t try to find out exactly where they were (I was tracking a family of Canada Geese both days). Here’s a calling toad from Pennsylvania, so you know what they sound like.
These were the first toads I’ve heard this season; Chorus Frogs (Pseudacris triseriata) have been calling since March 21 (a late start for them). I’ve featured our local American Toads a few times here at WEIT; here are a couple of featured WEIT toads from 2015.
American toads, Greenquist Woods, UW-Parkside, Kenosha, WI.
I’ve mentioned in previous posts how I periodically engage in turtle or frog and toad “rescues”, taking animals that had fallen into human made traps, such as window wells and stairwells, and releasing them, sometimes after feeding them for a while in captivity to fatten them up prior to release. A couple of days ago I decided to stop and check a stairwell on my campus, the University of Wisconsin-Parkside, where I’ve previously found toads and a turtle, and sure enough I found a young American toad (Bufo americanus), about 30 mm in snout-vent length, hunkered down in some leaf litter at the bottom of the stairs. I took the little fellow’s picture with a lady bug, the type of beetle made famous by Jerry’s academic grandfather Theodosius Dobzhansky.
American Toad with ladybug in stairwell, University of Wisconsin-Parkside, Somers, Wisconsin, 16 August 2016.
The beetle of course was not trapped, and could just fly away when it wanted to. I checked the same stairwell again the next day. It had rained in the general area the previous night, which might encourage toads to be moving about– and thus fall down the stairs– but I wasn’t sure if it had rained on campus. There were two more American toads. These were smaller, about 18 mm snout-vent length. (A penny is about 19 mm in diameter.) These two were hopping about— they had just fallen in, and were in good shape. The toad from the previous day, although it looked good, may have been stuck in the stairwell for some days during a generally dry period, and was not active, but rather hiding in the leaf litter.
American Toads from stairwell, University of Wisconsin-Parkside, Somers, Wisconsin, 17 August 2016.
Here’s the stairwell, on the northern side of the Communication Arts building, in which the toads (and last year a painted turtle) got trapped. This year’s larger toad was under the leaves on the far right. Once they go down a step, they cannot climb back up, and they get ratcheted to the bottom.
Stairwell at UW-Parkside, NE corner of Comm Arts extension, 16 August, 2016.
I released these toads immediately after photographing them in Greenquist Woods, shown in the photo below, approximately under the large basswood leaves visible at the right. You can see how the ground slopes down to the left– just behind that screen of bushes is Greenquist Pond, which is where the toads breed, and the painted turtles live.
Greenquist Woods, University of Wisconsin-Parkside, Somers, Wisconsin, 16 August 2016.
Here’s Greenquist Pond looking north, with Greenquist Woods to the north and east, a lawn area (not well seen) behind bushes to the west, with a sidewalk and lawn edging to the south (from where the photo was taken).
Greenquist Pond, University of Wisconsin-Parkside, Somers, Wisconsin, 16 August 2016.
The smaller toads were recent transformlets from tadpoles this season. The 30 mm toad was a bit puzzling. Either it’s a transformlet from earlier this year which has grown quite a bit, or it’s a one year old from last year’s brood. It seems too small, based on my experience of toad growth in captivity, to be a year old, yet it seems odd to have in just one breeding season such a wide size range in the season’s transformlets (18 to 30 mm). I’ve not quite worked out the breeding phenology of the toads– perhaps I should figure this out.
After releasing the 30 mm toad in the woods the first day, I stopped at the Pond with the colleague who accompanied me, and there we found many small frogs that jumped in the water. At the size of those we saw, you need to get a good look at them to tell bull frogs (Rana catesbeiana) from Green frogs (Rana clamitans)– both species occur in the Pond. They all were diving quickly in the water, and we had no binoculars to get a close look at those that surfaced in the water, but one large individual sat still and let me approach. It was a large adult male green frog: a green frog, because the dorsolateral ridge extends from the eye over the ear and along the side toward the groin (in bull frogs, the ridge curls round the ear); and a male, because the ear is larger in diameter than the eye.
Large male Green Frog in Greenquist Pond, University of Wisconsin-Parkside, Somers, Wisconsin, 16 August 2016.
Following up on Matthew’s linguistic investigation of larval amphibians, I’d like to address another amphibian linguistic conundrum: the English words for adult members of the order Anura. Just as we have two standard words for a larval anuran in English, we have two standard words for the adults: frog and toad. But this linguistic duality comes nowhere near encompassing the biodiversity of anurans. There are, by many estimates, over 40 families of anurans. I myself consider this taxonomy a bit oversplit, but even a conservative taxonomy would have more than two dozen families. There are thus many more sorts of anurans than there are English words to name them. Why is this so?
The answer, I believe, is simple. In Great Britain, where the language developed, there are four native species: two frogs (Rana temporaria and Rana lessonae), and two toads (Bufo bufo and Bufo calamita). So in England, there are indeed only two sorts of anurans. Here’s one of the frogs, the common frog (North American readers will note the resemblance to our wood frog, Rana sylvatica, which also has a tympanic dark spot and dorsolateral folds):
The Common Frog (Rana temporaria), near Bad Kohlgrub, Bavaria. Photo by Richard Bartz (Wikimedia).
And here’s one of the toads, the common toad (the green flecks are duckweed or some other plant):
Common Toad (Bufo bufo), Broomscroft, Kent. Photo by Peter K. Moore.
We can distinguish frogs from toads, because frogs are more aquatic, with long hind limbs for jumping, webbed toes (easily seen above), and moist, smoother skin. Toads are more terrestrial, squat with short legs for hopping, and have dry, warty skin. And this distinction works for the anurans of Britain– the frogs are members of the family of “true frogs”– Ranidae, while the toads are members of the family of “true toads”– Bufonidae.
As the English encountered more kinds of anurans around the world, each new anuran was shoe-horned into being either a frog or a toad. Thus the long limbed, arboreal, jumping anurans of the family Hylidae (which English nobility would have encountered in their Continental estates) were called, aptly enough, tree frogs. And in the North American colonies, the squat, warty burrowing members of the family Pelobatidae were called spadefoot toads. But with dozens of families of anurans, and a great diversity of ecological habits and body forms, the distinction breaks down, and our English common names wind up forcing an exuberant diversity into just two names.
I wonder to what extent the biodiversity of a language’s native land influences the language’s naming diversity. In the only other language I (sort of) speak, Spanish, I know three words– rana (for frogs), sapo (for toads), and maco. The latter is a word I learned in the Dominican Republic, and it has a very different meaning in standard Castilian, as given by the Real Academia Española: it means ‘knave’ or ‘rogue’ if converted to a noun (in Castilian it is an adjective). It’s possible that the Dominican word is of Taino or West African origin, rather than Spanish.
So, I’d like to ask our non-Anglophone readers, how many words for kinds of adult anurans are there in your language? And how does this compare to the biological diversity?
[The title of the post refers of course to a story about demons in the Gospels. A Roman legion had 6,000 men (and there are about 6000 species of anurans). If each family of anurans should have a common name, there names would not be quite legion, but there would be a lot more than two!]
In a previous post here at WEIT, I’d reported on some toads and a painted turtle that I’d rescued from stair and window wells, and then released back into the wild last spring. I’d mentioned at the time that I periodically check these places, especially a deep (ca. 20 feet down) window well on the west side of the building my office is in, because it faces a pond and woods, and animals coming out of the woods regularly fall down into it. So at the beginning of the semester in early September, I took my vertebrate zoology class out during our first lab period, and we investigated the window well. There was a pretty good ‘crop’ this fall– eleven American toads (Bufo americanus), and 23 green frogs (Rana clamitans).
American toads just outside Greenquist Woods, Kenosha, Wisconsin, 17.ix.2015. There are clearly six of them, the same ones as in “Spot the toads“.
The toads fell into two size classes: medium (in picture above), about 55 mm snout-vent length, and small, about 40 mm. The green frogs were all about the same size– 35 mm. These latter were probably all a single age class, having metamorphosed from tadpoles earlier in the summer, and then hitting the building and falling in the window well as they began to disperse away from their natal pond. Bullfrogs (Rana catesbeiana) are also common in the pond, but we’ve never found them in the window well– they must have different dispersal behavior.
Chris Noto helps to release American toads in Greenquist Woods, 17.ix.2015.
Frogs and toads are collectively known as anurans— it means “not having a tail”– and adult frogs and toads do, of course, lack tails. The anurans we rescued from the window well had been there varying lengths of time, but most were in at least decent shape, though some were thin and dehydrated. We kept them in the lab for a couple of weeks, feeding them and rehydrating them. We then released them on two warm days just as autumn was about to begin. My colleague Chris Noto was teaching a lab on a floor looking out over the woods, and he saw me encumbered with toads as I attempted to take their pictures and carry them back out to the woods. He came down and helped with the pictures and the release (which were featured in two “Spot the __” posts, on frogs and toads).
Small American toad, about to be released into Greenquist Woods, 17.ix.2015.
The green frogs were released a few days later.
Green frogs anxiously await their transfer to the pond, 20.ix.2015.One last picture.Well, maybe just one more.And then it’s time to re-enter the pond.Green frogs queue up to enter Greenquist Pond, 20.ix.2015.
[JAC: a video of the release. I have to commend Greg for both taking the time to rescue these frogs and also calling them to our attention. Frogs are not only underappreciated animals, but are harbingers of human damage to the environment, climatic and otherwise. And I’ve always said that if frogs hadn’t evolved, we simply wouldn’t be able to imagine them!]
There are at least a dozen or more different sorts of anurans around the world that are worthy of their own vernacular name, but because only two sorts occur in England, we are stuck with calling them all either “frog” or “toad” in English. The American toad and the green frog do, however, correspond to the two sorts found in England (what are sometimes called the “true toads” and the “true frogs”, respectively).
Anurans are amphibians, and like most amphibians, have a complex life cycle. The word “amphibian” alludes to this– it means “both lives”, because a typical amphibian lives both on the land and in the water. Reptiles and their descendants (the amniotes, including birds and mammals), do not have this dual life cycle. One of the former candidates for the title of “first reptile” was the 270 million year old Seymouria, which has reptile-like features; but when it was found that its close relatives had aquatic larvae with gills, it was clear they were not reptiles, but rather led the “both lives” of an amphibian.
“Both lives” does not seem to adequately summarize the life of a typical amphibian, such as the American toad. They begin life as eggs in water, hatch out as tailed, gilled, tadpoles, that then swim about, eventually losing their tails and gills and sprouting legs to transform into toadlets, which then move onto land. After sexually maturing, they return to the pond each spring, to resume an amphibious existence, there to mate and reproduce. The adults then leave the pond for the summer to live wholly on land, while their eggs begin the complex cycling again. To paraphrase The Who, “Amphibians? They’re bleeding Quadrophibians.”
A further salientian post is coming, but since people seemed to have such fun finding the frogs, I thought I’d add a quick post on spotting the toads.These are American toads, part of the same “rescue” as the green frogs featured yesterday. I think getting the count right on this one is actually a bit trickier.
Bufo americanus next to Greenquist Woods, Kenosha, WI, 17.ix.2015
Regarding those frogs from yesterday and how many there were, I had released 18 of them, and did not know how many were in that particular picture, as I just snapped a few shots as they scurried away. The frog-like thing in the lower right is, as several readers noted, a rolled leaf; it does look froggy at first glance, but zooming in reveals its true nature. (On my screen, clicking, and then clicking again, produced the usual magnified image– I’m not sure why it didn’t work for many readers. At least we all learned about ctrl + scroll (crtl+<+> also works)!) I count four frogs. However, regular reader Jim Knight, who is a very experienced field herpetologist, said he saw five, so I’m not excluding the possibility I’ve missed one myself.
Update: Yesterday afternoon on the way home, at about 5:30 PM, just hours after posting this, I came across a large snapping turtle (Chelydra serpentina) crossing in the middle of the road. It was a windy 2-lane road with a mix of homes, woodland, and fields (Wood Road, between A and KR in Somers, WI). The car ahead of me maneuvered around the turtle, and pulled into a long driveway. I pulled off just behind the turtle (though my car was still half on the road– there’s really no shoulder there), put on my flashers, got out and picked it up. It was big, 11.5 inches carapace length (measured by marking off on a stiff map I had in the car– I didn’t have a meter stick with me), a smooth shell with lots of algae growing on it, and very snappy– much more so than a captive turtle that’s used to people: a magnificent specimen. I tried one-handing it by the back of the shell, but couldn’t do it, so I grabbed one thigh in each hand and held it with its plastron toward my leg (so it couldn’t reach out and bite me, which it wanted to do). The driveway that the car went in led up hill into the woods, and I didn’t see anyone. There were no obvious bodies of water to bring it to, so I rang the bell at the house where I parked, but it looked dark. Looking back down the road, I saw a guardrail (which are often placed by ditches/water), walked down to it, and found a small creek going under the road coming out of a fairly dense woods, so I let it go on the edge. (A big frog jumped out of the way as I let it go!) As I walked back to my car, the neighbor whose bell I had rung came to the side of the road. As I explained, he said there were five ponds back in the woods where I’d let it go, and that he saw big snappers wandering around occasionally, although not one that big recently. He was a good observer, since he knew details about snappers that most people don’t. We both thought it would be just fine back there, which was in fact probably where it had come from. Unfortunately, I did not have camera to take a picture. This morning on the way to campus, I checked the road carefully– no carcass or blood stains. It either stayed in the creek/woods/ponds, or if it persisted in trying to cross, it made it across safely.
I am occasionally contacted by local or state authorities to assist in identifying, capturing, and/or taking care of reptiles that have, for various reasons, come to their attention. Sometimes this involves animals that are suspected of being inadequately cared for; such cases have come to be called “rescues”, a term that I am not entirely happy with, but which I use since everyone else does. There are cases though where the animal needs rescue, even though no direct human action has caused its predicament. Here are two such cases.
Early in May, I went out one evening with a friend and his son to look for frogs and toads, to help his son work on his Reptile and Amphibian Study merit badge. We were heading to Greenquist Pond, a small, artificial farm pond, now surrounded on two sides by woodland, on my campus. I decided to stop at an outside stairwell to the basement of a building near the pond, knowing that small animals can go down the stairs, but not up. In the leaf litter at the bottom of the stairs, my friend found a hatchling midland painted turtle (Chrysemys picta marginata).
Chrysemys picta marginata, UW-Parkside, Kenosha, WI, 6 May 2015.
When first found, the turtle was entirely immobile– I feared it was dead. A few minutes of being held in the hand, though, warmed it up, and it became active. We brought it back to the lab to be measured (26 mm carapace length) and photographed. Left in the stairwell, it would have undoubtedly died, as the steps were much too high for it to climb up, and in the stairwell it would have starved, died of cold, or been eaten (by a visiting bird or raccoon, or perhaps by a shrew, which also get trapped in stairwells and starve, but will eat anything down there with them before they do). We went on to see and/or hear at one or more of Greenquist Pond, Desch Pond, and the Willow Swamp bull frogs (Rana catesbeiana), green frogs (Rana clamitans), American toads (Bufo americanus) and chorus frogs (Pseudacris triseriata).
The hint of red you can see on the marginal scutes in the photo above is well developed on the plastron.
Plastron of hatchling painted turtle.
The turtle was a hatchling, but was from 2014’s egglaying. It had hibernated over the winter (perhaps in the nest), had emerged in spring 2015, but made a wrong turn on the way to the pond, and found itself in the stairwell. Once over the first step, it was ratcheted down to the bottom– it can fall down a step, but cannot go up a step. I was very glad to see it, since I had not found any painted turtle nests near the pond for some years, and feared that changes in land use around the pond might have turned the resident painted turtles into a non-reproducing population. The hatchling proves they are reproducing, and the location of the stairwell relative to the pond indicates they are nesting at least close to where they used to, although I’ve not found the nests.
After a few days in the lab, it was time to release the little fellow in the pond. Here he is on a patch of moss near the edge of the pond.
Hatchling painted turtle about to enter Greenquist Pond, UW-Parkside, Kenosha, WI.
And here he is entering the water.
The previous September, I had found five American toads (Bufo americanus) in that same stairwell, and seven more in a deep (ca. 20 feet) window well outside my building (which is also quite close to Greenquist Pond and adjacent patch of woods). I typically go down the ladder into the window well when out with my vertebrate zoology class, because we often find trapped vertebrates in there (frogs, toads, small rodents). We brought the toads back to the lab for identification and measurement. Some of them were quite emaciated, and I decided to hold on to these for a bit to try to fatten them up before releasing them. Another was one of the largest American toads I’ve ever found around here, and I kept her to get some photos. But after releasing the others, the weather got cold before they fattened up or I got a chance to take photos, so I wound up keeping the big female and one of the emaciated toads over the winter (the other emaciated toad was eaten by the big female!). I released them in Greenquist Woods the same day this spring that I released the turtle.
American toads, Greenquist Woods, UW-Parkside, Kenosha, WI.
Here they are (above), just after release, the formerly emaciated male on the left, the big female on the right. At the time of capture, the female was 75 mm snout-vent length. When released, she’d grown to 84 mm, and weighed 84 g. I’m not sure exactly how big the emaciated male was when captured, because I didn’t segregate the measurements of the emaciated ones I kept, but the set of smaller ones caught had sizes ranging from 20-32 mm. By the time of release he’d grown to 66 mm and weighed 31 g, and gotten kind of chubby even. He had also sexually matured, having keratinous nuptial thumb pads, grabbing onto the female’s back and holding tight (as males do during amplexus), and giving the “release” call when squeezed at the waist (as males and unreceptive females will do). In the wild, of course, he would not have grown over the winter, and thus may have sexually matured a year earlier relative to his cohort.
Here are portraits of them, taken just before or just after release.
Male Bufo americanus, UW-Parkside.Female Bufo americanus, UW-Parkside.
I’d mentioned that these animals’ predicaments were not due to direct human action, but their need for rescue did arise from human action– essentially we’ve dotted the landscape with inescapable pits– just not from actions directed at the animals.
(And of course, toads are amphibians, but ‘reptile rescue’ is more terse and euphonious.)
