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.
A bullfrog (Rana catesbeiana) on the shore of Greenquist Pond, Somers, WI, 5 May 2021.
And speaking of late, it’s been a very late season for amphibians here in southeastern Wisconsin. The picture above is from May, 2021, because it’s been a very cold spring, and there’s been hardly any amphibian activity. Normally, chorus frogs (Pseudacris triseriata) begin calling in mid-March; this year I first heard them on April 7, and, since then, calling has been only sporadic. A year ago, American toads (Bufo americanus) began trilling the first week of May; I haven’t heard any yet. I have seen one adult bullfrog, in the last week of April. It was actually quite large– I spotted it with my naked eye across the Pond while scanning for turtles. (Turtles are out, but not in large numbers or consistently.)
Among the participating organizations is the Department of Defense PARC, which is charged with protecting and managing amphibians and reptiles on military lands, and they have been sending interesting items all week. One of the most fun ones for me was an amphibian identification quiz. It was done as a Powerpoint file, but I can’t figure how to set it up here in WordPress, so you’ll have to take my word for it 馃檨 . They sent a nice guide to modern amphibian origins:
And this set of links:
When folks think of migration, usually, people think of birds and whales carrying out this process. However, did you know that some of our amphibians migrate, too? When the night is right, thousands of spotted salamanders will make their way to temporary wetlands known as vernal pools to breed in the spring. Checkout this great video by the Tennessee Aquarium: https://youtu.be/8xGZ8SLqVa8
Looking for some educational inspiration to teach about salamander migration and vernal pools? If so, check out this resource list put together by Of Pools and People: https://www.vernalpools.me/ecology-2/
Check out how the Boreal Toad was brought back to Colorado by biologists working to reintroduce the species and how they鈥檝e been affected by a decimating fungus: https://www.youtube.com/watch?v=x9RQVA_d1DU
Gifford Pinchot National Forest biologists created breeding habitat for the threatened Oregon Spotted Frog through an innovative interagency conservation project in this video: https://vimeo.com/278211745
As I’ve tweeted and also indicated in today’s Hili Dialogue, Bob Dylan turns 80 today.聽 Reader Joe McClain called my attention to a letter that the President of Ireland wrote Dylan in honor of the occasion. It speaks for itself, though I didn’t know that the Irish President was a poet. Here it is (click to enlarge):
For the end of Amphibian Week, we have a photo gallery, starting with my late, lamented, Toady, who was collected by David Wingate, Bermuda’s foremost naturalist, in 1999, and who died in 2019, at the age of 20+ years. The Giant Toad, Bufo marinus, (also known as the Marine Toad or Cane Toad) is native to the continental American tropics and subtropics, and was introduced to Bermuda.
Giant Toad, Bufo marinus, Bermuda (collected in 1999; photo taken in 2012).
Note the enormous parotoid gland behind the eye, which secretes poisons that can protect the toad from predators.
Giant Toad, Bufo marinus, Bermuda (collected in 1999; photo taken in 2012).
My thanks to Chris, who has been distributing amphibian images, documents, and links throughout Amphibian Week. (If you’re wondering why the Department of Defense is involved in conservation, we’ve dealt with that before at WEIT. The short answer is that 1) the military must obey applicable environmental and conservation laws on military lands, and 2) certain animals pose practical issues for the military (e.g., venomous snakes). The Navy, which I know best, employs a number of professional herpetologists. Recall as well that the military has often enabled scientific exploration (the Beagle, for example, was a Royal Navy ship), and military reservations have sometimes had the best preserved habitats (e.g., much of the Patuxent National Wildlife Refuge was annexed from Fort Meade.)
Department of Defense Partners in Amphibian and Reptile Conservation. 2019. Department of Defense Herpetofauna Conservation Status Summary. Department of Defense Legacy Resource Management Program. pdf
The theme of today’s post is threats to amphibians.
In the above graphic, “41%” of amphibians are threatened”, may seem improbably precise, since threatened species are usually identified by the realization that some species is under threat, which then gets the species added to the IUCN’s Red List, an authoritative compilation. But the Zoological Society of London‘s Institute of Zoology has for a decade been implementing a “Sampled Red List Index“, which, instead of seeking out threatened species, assesses a large, random, sample of an entire higher taxon, thus giving a valid estimate of the proportion threatened. (I worked on the reptile SRLI, which assessed 1500 species).
One major threat to amphibians has been the global spread of the chytridfungus, Batrachochytrium dendrobatidis, which infects amphibians and can wipe out whole populations and species. Chris Petersen, of Department of Defense Partners in Amphibian and Reptile Conservation, sent me links to the following reports on surveys and assessments that have been conducted concerning the chytrid threat to amphibians inhabiting military lands.
I especially liked the first survey, a transcontinental transect study from California to Virginia; it found chytrid at all but one location.
Figure 1 from Petersen et al. (2011).
This and the second study were coauthored by, among others, my colleagues Rob Lovich and Mike Lannoo; Rob has previously treated WEIT readers to World Snake Day, and Mike has authored or coauthored several major works on amphibian conservation, including the monumental Amphibian Declines: The Conservation of United States Species. (The titles of these two reports also show the authors’ knowledge of song lyrics!)
We’ll finish off today’s installment with the non threatened Wood Frog (Rana sylvatica), which is widespread in North America. A northern species, a number of relict populations have survived in mountains south of the main range, left behind as the species followed the retreating glaciers north. This fellow’s from the main range in northern Minnesota, near Lake Superior.
Wood frog, Lutsen, near Lake Superior, Minnesota, 6 June 2014.
h/t C. Petersen, G. Wood
B枚hm, M., B. Collen, … G.C. Mayer… et al. 2013. The conservation status of the world’s reptiles. Biological Conservation 157:372-385. pdf(MS)
Lannoo, M.J., ed. 2005. Amphibian Declines: The Conservation of United States Species. University of California Press, Berkeley. publisher
Petersen, C., R.E. Lovich, M.J. Lannoo, and P. Nanjappa. 2011. Do Frogs Still Get Their Kicks on Route 66? A Transcontinental Transect for Amphibian Chytrid Fungus (Batrachochytrium dendrobatidis) Infection on U.S. Department of Defense Installations. Proj. No. 09-246, Department of Defense Legacy Resource Management Program. pdf
Petersen, C., R.E. Lovich, C. Philips, M. Dreslik, P. Nanjappa, and M.J. Lannoo. 2013. From the Mountains to the Prairies鈥擲easonal Bd Responses Differ by Latitude and Longitude at a Continental Scale. Proj. No. 10-426, Department of Defense Legacy Resource Management Program. pdf
Petersen, C., K.L.D. Richgels, G. Lockhart, and R.E. Lovich. 2019. Salamander Chytrid Fungus Risk Assessment on Department of Defense Installations. Department of Defense Legacy Resource Management Program. pdf
For the midpoint of Amphibian Week, Chris Petersen of Department of Defense Partners in Amphibian and Reptile Conservation sent me these amphibian facts.
Characteristics of Amphibians:
路 Include frogs and toads, salamanders and caecilians (approximately 8,300 species worldwide)
路 All are vertebrates (have a backbone)
路 Are ectothermic (meaning they rely on external sources from the surrounding environment to maintain their body temperature)
路 Most live part of their life in water and part on land (although there are many exceptions)
路 Most have moist glandular skin through which they can respire (breathe) to various extents (some exclusively so, but most also through lungs or gills)
路 Lay unshelled (jelly-like) eggs in moist to wet environments
路 Most go through a process called metamorphosis to develop from a water-living life stage to a land-living stage
I then headed out to Greenquist Pond here at UW-Parkside to see what amphibians were about. You’ll recall that Chorus Frogs and American Toads have been calling on campus, but I hadn’t seen them at this pond. Here’s what I found.
Bullfrog, Rana catesbeiana, Greenquist Pond, Somers, Wisconsin, 5 May 2021.
I walked around three sides of the pond, and heard or briefly saw several Rana jump into the water, many emitting a little “yelp” as they dove in. I think both Green Frogs (Rana clamitans) and Bullfrogs (Rana catesbeiana) make that noise, so I wasn’t sure of the species. All were smallish, except for one that was bigger, but could have been either a large Green or a medium Bullfrog in size. I was heading back, reconciled to failure, when I spotted this medium-sized Bullfrog on the bank, which didn’t spook. I was able to get pretty close to get this shot, and even was using sticks to bend shadowing leaves out of the way, but it stayed put.
The Green Frogs and American Toads I showed in earlier Amphibian Week 2021 posts were also from this pond, but I’ve not seen them at the pond yet this year. (Some of the frogs today may have been Green Frogs.)
There were also turtles, so I’ll cheat a bit (they are reptiles, of course) and throw them in here. There were four five Painted Turtles (Chrysemys picta),
plus this Red-eared Slider (Trachemys scripta elegans), with another two Painted Turtles behind.
Red-eared Slider, Trachemys scripta elegans, and , in back, two Painted Turtles, Chrysemys picta, Greenquist Pond, Somers, WI, 5 May
There were a total of four five Painted Turtles, all with the slider in this corner of the pond. The slider is the most popular turtle in the pet trade, and is not native to Wisconsin. Although we find them not infrequently, they all seem to be released or escaped– they don’t seem to breed up here, even though they can survive the winters. (I had my own “Spot the …” moment– I didn’t see the further back Painted Turtle in the above photo until I’d posted it here!)
I’ve received another batch of amphibian goodies for Amphibian Week. Department of Defense Partners in Amphibian and Reptile Conservation suggests having a look at this video about the Hellbender (Cryptobranchus alleganiensis), a giant permanently aquatic salamander, and the largest (heaviest) amphibian in the Western Hemisphere. When I took herpetology as a summer course at Cornell University in upstate New York, there was a thrill when visiting a drainage in which hellbenders could occur; the mere possibility was enticing. Alas, we didn’t find any.
The Eastern Newt (Notopthalmus viridescens) and the Bullfrog (Rana catesbeiana) are common through much of the eastern US (the latter is also widely introduced in the west), and DoD PARC has produced fact sheets on both of them. This website explains, for kids, some of the differences between frogs and toads, but the problem with trying to distinguish frogs from toads is that there are many more kinds of members of the amphibian order Anura than just frogs and toads. “True toads” (Bufonidae) and “true frogs” (Ranidae) are only two of the dozens of families of anurans. We have two words in English, which correspond to the two genera (Bufo, toads, and Rana, frogs)聽 which occur in England, but these aren’t enough; we tend to shoehorn that diversity them into either ‘frog’ or ‘toad’
We’ll finish off today with a species common in SE Wisconsin, the Green Frog (Rana clamitans). The relatively small eardrum would suggest this is a female, but it’s fairly small, and might just not have developed sexually dimorphic features yet.
Green Frog, Rana clamitans, UW-Parkside, Kenosha, WI, 20.ix.2015.
And here’s a bunch more. These were all rescued from a deep (ca. 20 foot) window well, and then released into nearby Greenquist Pond.
Green Frogs, Rana clamitans, UW-Parkside, Kenosha, WI, 20.ix.2015.
