Wednesday, February 21, 2018

My 2017 Amphibian Review

This past week, temperatures in Ohio soared into the mid-60's, and rain soaked the ground. Although it was still a bit early, some of the salamanders and frogs across the southern half of the state decided they would attempt the journey from their overwintering territories to their vernal pools in hopes of breeding. Their attempts were premature—the weather soon dipped below freezing, and a snowstorm moved across the state—but it got me excited for springtime. To get me through the remaining days of winter, I've decided to put together two posts reflecting on some of the species of amphibians and reptiles I saw last year. I'll start with the amphibians, as they are the first of the "herps" to become active during the year.

Spotted Salamander Ohio
Every year, people from around the eastern US look forward to the annual salamander migration. Throughout the forests of the east in the early spring, several species of salamanders belonging to the family Ambystomatidae venture forth from their subterranean homes and migrate upwards of a mile overland to reach vernal pools and ponds to breed in. This event is triggered by the weather, and it typically occurs the first night in spring in which the soil is not frozen, the air temperature remains above 50 °F, and it is either raining or it had rained all day and the ground is still wet. In southeast Ohio, "the night" happens most often between mid-March and the beginning of April. But 2017 was an abnormal year; we experienced extremely wet and warm nights toward the end of January and throughout February. This triggered some, but not all, of the salamanders to migrate early, such as this Spotted Salamander (Ambystoma maculatum) which migrated to a vernal pool on the night of February 7th, 2017—over a whole month earlier than what it normally would.

Jefferson Salamander Ohio
The Spotted Salamanders weren't the only migratory species to be out the night of Feb. 7, 2017. This Jefferson Salamander (Ambystoma jeffersonianum) was also making his way to a vernal pool. Migrating early, especially if a cold snap occurs right after, can be quite harmful for such migratory salamander species. Right after that night, people posted photos of vernal pools full of dead Jefferson Salamanders late last winter—they had frozen to death. Such instances will most likely increase in the future, as Ohio will face an increase in abnormal weather patterns due to climate change. Ohio is predicted to experience higher winter and spring rainfalls and warmer winter and spring temperatures over the next 100 years, and this will undoubtedly affect migratory salamanders.

Just how it will impact the salamanders is uncertain, but the end effect will more than likely be detrimental. Warmer temperatures and rainfall events earlier in the year will most likely trigger Ambystomatid salamanders to migrate earlier and breed earlier. In addition to the possibility of freezing to death due to the ever present threat of cold snaps in late winter, we could also possibly end up seeing an "out-of-sync cycles" effect, in which the salamander larvae are in the vernal pools, but their food might not be there. We are already seeing this occur with various species of birds. Migration in birds is relatively fixed and triggered by the amount of daylight. Their migration is supposed to be synchronized prior to the peak of mass insect activity so the nestlings will have abundant food available, but insect activity is happening earlier and earlier due to climate change. This is resulting in birds migrating to an area without that much food, and nesting success is decreasing because of it. Could we see such a problem arising with migratory salamanders? Although it’s too early to tell, it’s something herpetologists will be keeping tabs on over the years.

Northern Slimy Salamander Ohio
Not all salamanders migrate; in fact, the vast majority of species don't. For example, of the 24 species of salamanders which can be found in Ohio, only 7 migrate. The others are either fully/mostly terrestrial or fully aquatic, and they breed where they live. One of the more common terrestrial and non-migratory salamanders in the state is the Northern Slimy Salamander (Plethodon glutinosus glutinosus). This species can be found throughout the southern and eastern halves of Ohio. Their name stems from their defensive behavior; if a predator (or a curious human) messes with a Slimy Salamander, the salamander will excrete this incredibly sticky and glue-like secretion from its skin. It will then try to rub this secretion all over the potential threat, which will hopefully deter whatever that threat is.

Red Salamander Ohio
One of my absolute favorite salamanders to see is the Red Salamander (Pseudotriton ruber). This species is a large one, with adult individuals coming in at 5-7 inches in length! The Red Salamander can be found throughout the eastern half of Ohio, where it spends its time either hiding under rocks and logs alongside forested brooks and springs, or within the water itself.

Red Eft Red Salamander Mullerian Mimicry
You might be wondering why it would benefit a salamander to be so vividly colored. Wouldn't a large red and black salamander scream "EAT ME" to predators? Well, it's actually the opposite! Bright coloration can be a sign of toxicity. Such conspicuous coloration/patterning is called aposematic coloration, which is more commonly known as a warning coloration. The Red Salamander, for example, has a toxin located throughout its skin which makes it poisonous to potential predators. As a result, the species evolved aposematic coloration to warn predators that messing with them is probably a bad idea. But there's something more complex going on than just simple aposematism. Several salamanders in the eastern US have evolved a similar red/orange coloration with black dots, and it seems to be a case of mimicry. Take, for example, Red Salamanders, Mud Salamanders, and the Red Eft stage of the Eastern Newt. All three of these species are toxic, and they have all converged on a similar red/orange coloration with black dots. This is a case of Mullerian mimicry, in which two or more toxic species converged on a similar appearance. The evolutionary idea behind Mullerian mimicry is that predators will only have to learn to associate one type of coloration with danger, despite there being 2+ toxic species in question. Mullerian mimicry benefits both the toxic species—which are more likely to be recognized as dangerous—and the predators—which are more likely to recognize the danger.

Long-Tailed Salamander Ohio
One last salamander! Meet the Long-Tailed Salamander (Eurycea longicauda). For years, this species had evaded me; and then 2017 happened. Not only did I see my lifer early in the summer, but I ended up seeing several more throughout the year, including 3 on one day! As the name implies, the Long-Tailed Salamander has an extremely long tail relative to its body; in fact, the tail typically accounts for around 60% of its total body length. They're a strikingly beautiful species, but it can take some searching to see one. The Long-Tailed Salamander can be found throughout southern and eastern Ohio, where they typically inhabit limestone or shale-based streams, caves, and springs. While the adults are terrestrial, the larvae are fully aquatic, and so the adults typically live close to appropriate aquatic habitats. In such appropriate locales—typically alongside streams or nearby seeps and springs—they spend their day foraging underneath rocks and logs. The individual pictured above was found in Adams County, where it was living under a limestone rock by a stream with a limestone bed.

Eastern Spadefoot Ohio
It wouldn't be a post on amphibians without mentioning frogs, so I'll end on with the most exciting amphibian species that I saw in 2017. This is the Eastern Spadefoot (Scaphiopus holbrookii). The Eastern Spadefoot is a notoriously hard species to see in Ohio for two reasons: their rarity and their life history. Regarding its rarity, the Eastern Spadefoot is listed as Endangered in the state of Ohio. Although it's hard to find exact information on their current range in Ohio—different organizations don't seem to agree on which counties have and don’t have populations, and just how many of those populations are extinct and extant—it can be safely said that this species has only ever been found in a handful of counties. Of those recorded populations, many have died out over the past century due to a variety of reasons, both known and unknown. ODNR reports that only 5 distinct populations of the Eastern Spadefoot remain in Ohio, and no one really knows how how many individuals are in each of these populations.

Scaphiopus holbrookii Ohio
Regarding its life history, the Eastern Spadefoot has a lifestyle that makes it rather difficult to go look for, even if you know exactly where a population is. The Eastern Spadefoot is an explosive breeder that's more akin to frogs inhabiting the desert southwest. For nearly the entirety of the year, this frog stays underground, where it lives in burrows in sandy areas adjacent to a few rivers in southeastern Ohio. When they're underground, they're essentially impossible to detect. They only emerge to breed, and breeding is triggered by very specific weather conditions. If there is a torrential rain event of 2+ inches of rain within a 24-hour period between the months of March and September, dozens and dozens of individuals might venture forth from their subterranean homes come nightfall to breed in the ephemeral pools the heavy rainfall created. The individuals pictured in this post were found on a visit to a known location in Athens County (all locations are kept secret to prevent unnecessary strain on the population) after nearly 2.3 inches of rain fell over the course of one and a half days.

Eastern Spadefoot Burrowing
Eastern Spadefoots are strange. They look strange, they sound strange, and they have a strange life history for a frog species that lives in the eastern US. The unusual name of "spadefoot" comes from a darkly-colored, hardened spur on their back legs that they use like a spade to help them dig into loose, sandy soil. With use of this specialized "tool," a Spadefoot can easily—and quickly—burrow into the soil, like the individual above. I couldn't get a photo of the spade (because the Eastern Spadefoot is endangered, it is illegal to touch the animal), but here is a link that will show you what I'm talking about: Spadefoot spade.

In a few days (or a couple weeks) I'll be posting the second installment covering some of my favorite reptiles from 2017, so keep your eye out for that post! Thanks for reading!