Woodland Amphibians: Frogs and Salamanders

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- Hi, Sanford Smith here with Penn State Extension.

Today, I'm joined by Julian Avery.

He's a professor of research in wildlife conservation in the College of Ag Sciences at Penn State.

We're gonna talk about amphibians today.

Julian, what can you tell us about amphibians, especially now during the springtime, but also throughout the year?

What is their life cycle like?

- Yeah, thanks, Sandy.

Happy to be here today.

Early spring is a time when all the rains fill up all these frontal pools, like you see behind us.

And in Pennsylvania, we have quite a number of species that use habitats like this.

When the early rains come and fill these up, then the adults can come down out of the upland, the surrounding area around these ponds, and they lay their eggs in these pools.

The eggs will hatch.

There's lots of zooplankton and another little invertebrates for those larvae to eat in these ponds.

And then sort of by midsummer, towards the end of summer, those that use a habitat like this will metamorphose and go back up into the uplands to complete the cycle for the next year.

So spring is a really critical time because that's when these fill.

Later in the year, these will dry out, and so we have a whole host of amphibians that are uniquely adapted to taking advantage of this sort of temporary resource.

- Now, Julian, I wanna stop you right there because I suspect that some people aren't quite remembering their high school biology when we say amphibians.

What are we meaning when we say amphibians?

- Yeah, good question.

So amphibians are scaleless tetrapods.

So they have four limbs, right?

We have all manner of terrestrial and aquatic forms of amphibians, but they tend to lay unprotected eggs and they also tend to have a skin and tissue layer that is extremely permeable to gases and liquids.

So for most of our amphibians, they actually get a lot of their moisture and a lot of their air through the surface of their skin.

And that is also what makes them very susceptible to contaminants and other pollutants in our systems.

So they're a very sensitive group of animals because of the way in which their skin interacts with their environment.

- So from kind of a layperson perspective, we're talking about frogs and salamanders, or are there other types of amphibians?

- Yeah, so there's frogs, salamanders.

And then within those two groups, you can have things that you might call newts or toads, but they're all still frogs and salamanders.

- Now, you mentioned that after they mate and lay their eggs and such, they go back to the uplands.

And probably each amphibian has a slightly different pattern there, but we're not talking about mountains, we're talking about little hills, right?

- Yeah, so a vernal pool like this is actually a great example in that this resource is really important for the breeding period, right, and for the young to hatch and develop until they are suitable or at a stage where they can survive on land.

All of this surrounding area around this pool is actually really critical habitat for the adults.

Having a nice buffer, a nice protective amount of vegetation or other non-developed land is really important because that's where everything that uses this to breed will go for the rest of the year.

And a lot of our amphibians are actually quite deep underground eating invertebrates, doing really important things in the forest soils.

- Interesting.

- And so it's not necessarily that it's upland, but it's a sort of a general term we used to describe all the land that surrounds around the pool.

- [Sanford] Well, if you only stand about a centimeter high, then virtually any little hill is a mountain, right?

- Yeah, yeah.

And the salamanders that use these, for instance, they can go a couple hundred meters away from a vernal pool.

So actually, we like to have a lot of vegetated protective area around these to protect what uses them.

- Okay.

You know, I've heard that Pennsylvania is sort of a special place with a high level of diversity when it comes to amphibians.

- I would say Pennsylvania does actually have a high diversity of amphibians.

We're connected to the Appalachian region, so we are connected to the high diversity there.

And as you go further north from us, you do tend to drop off in species richness.

So we're kind of at the northern edge of a lot of species ranges extend into Pennsylvania.

So we're quite lucky for what we hold here.

- Yeah.

Well, I think I have two more questions.

Now, the first question is: What are the concerns that we should have about amphibians?

- That's a great question, Sandy.

There's a lot of things that have the potential to interact with amphibian populations in what I would consider negative ways.

Because of their susceptibility to things in the system making its way through the skin barrier, kind of a strange fact is that an amphibian, without its skin, actually loses water at the same rate that it would with its skin on.

So, you need to think of that skin barrier is being really permeable, really permissible.

And so because of that, anything that gets into the water or into the surrounding soils that they come into contact with can really be taken into the body very quickly and easily.

So thinking about how far systems are away from runoff or other things that might get into the system that we put into the soils or into the water is really important.

Climate change, thinking about how temperatures are shifting can put animals at odds with their environment and how they've evolved to interact with their environment.

So that's an important thing to think about.

And habitat loss is a really big one, right?

We like to convert landscapes into different forms of cover that maybe work better for what we need, but oftentimes those are at odds with what amphibians really need to survive on the landscape.

- Yeah, and I imagine just putting in a woods road in the wrong place can destroy a vernal pool and really cause a problem to their habitat. - Yeah.

So that's a great question.

So we're always thinking about placement and siding of development, right?

So this pool is relatively far from a gravel road, but if we had a road come in close proximity, a lot of that dust would begin making its way into this pool changing the water quality, changing the nutrient levels in there, and then you might upset the balance of little invertebrates that these amphibians eat and the plant life that might grow in there and use that resource.

- So Julian, one more question, and this is sort of a personal question.

What is it that really jazzes you about amphibians?

You spend a lot of time going out and looking for them at night and throughout the year.

What is it that is so special about amphibians?

- Yeah. No, that's an easy one to answer.

I think they're fascinating, they have such cool breeding displays, breeding calls, the way in which they use these habitats differently throughout the year.

It means that you can go out at any time of the year and see something new or see something surprising.

And there's really no shortage of unique things to see throughout the year, right?

If we're talking about species that use a pool like this, you get to come and watch them breed, you get to come and look at their egg masses, you get to then come and look at the larvae.

And then later in the season, you get to see those little larvae coming out shorter than your finger, right?

And they look awfully cute at that stage.

So the patterns, the complexity of life history traits and behaviors is just really fascinating.

- Yeah, thank you.

Now, I do wanna mention one other thing, that Julian is very active in social media and you post a lot of your photographs of amphibians, and reptiles, and other wildlife.

And if someone was gonna follow you, what would they have to do?

- Well, they can either find me on Instagram, @evolutionavery, spelled A-V-E-R-Y, or also on Facebook under Julian Avery.

And either those handles will find my other social platforms as well.

- Okay, and those are appearing right here on the screen.

So thank you very much for listening today and thank you, Julian, for joining me to talk about amphibians in the springtime and throughout the year.