Monday, September 15, 2014

Yet Another Snapper

I was walking around Ohio University several days ago with Olivia Brooks, who runs the Twitter account Wild Earth, a new all-around nature account. We were specifically checking out the small creek that currently runs through Emeriti Park, along the Oxbow Trail road, and out around West Green. This waterway wasn't always a small creek; this is actually the remnant of the Hocking River. The Hocking River used to cause major flooding for Athens and Ohio University. In the 1960's they began to reroute the Hocking River around the university, thereby making sure that it would not cause such major flooding in the future. What was left in the old riverbed was this tiny creek which helps feed two ponds in Emeriti Park, as well as helps divert rainwater to the Hocking River.

Ohio University Turtles
Find the turtle.
Even though the mighty river no longer flows here, the creek is still teeming with life. There's a muskrat who patrols the waters around West Green. I, along with many others, have seen Northern Watersnakes hunting for prey in the water. Many frogs call the creek home, as well as many small fish (I don't know the species present, but would love to find out). Dragonflies and damselflies patrol the skies above the creek hunting down other insects. But those aren't the only things lurking in or near the creek. This past Spring I found a hatchling Common Snapping Turtle in the creek and made a post about it. This time around, as Olivia and I were patrolling the creek, she pointed out a turtle up ahead of us.

Common Snapping Turtle, Chelydra serpentina
As we got closer we saw it was another Common Snapping Turtle, a decently-sized one at that. The Common Snapping Turtle, Chelydra serpentina, is the largest turtle species in Ohio. Their carapaces (the upper part of the shell) can reach lengths up to 20 inches, although 10-18 inches is the average. They usually weigh 10 to 35 pounds, although the largest wild specimen caught weighed about 74 pounds. Although we couldn't measure this individual exactly, it's carapace was about 9-11 inches long. Notice the long tail, one of the initial characteristics that might tell you you're dealing with a "snapper."

Common Snapping Turtle Ohio
I decided to get some close-up shots since he (or she) decided to just stay put as we watched him. I've never been able to inspect an adult Common Snapping Turtle so closely, so I definitely jumped on the chance to do so. This species has a large head with a pointy snout, as you can see above. Notice how rough the skin is around the neck. Also notice the black streaks around the eye. The eyes actually have similar markings, helping add to the camouflage. This camouflage not only helps to protect the individual from would-be predators (although an adult does not have many predators), but also helps it to be a better predator. Adults typically employ a "wait and ambush" technique when hunting. They will sit in the water without moving in an attempt to look like just another part of the creek or pond bed. Whenever some sort of prey gets close, they will lunge out and grab it. This species is opportunistic and will eat just about anything it can get, whether it be fish, insects, birds, or even small mammals. 

Common Snapping Turtle Tail
Another interesting aspect of the turtle that many people don't get to see is the serrated backside of the carapace. The carapace is also keeled, meaning it has raised, pointed parts of the shell. These are very pronounced when the turtle is young, but tend to wear down as they get older. An old individual might appear to have a flat carapace. The individual we found still had the keels present, but they were not overly pronounced. As a result, I would say this individual is probably between 5 and 15 years old. (Also to note, unlike box turtles and tortoise species, you cannot count the rings on their carapace scales to determine the age.) Dr. Sue, one of the professors at OU who specializes in turtles and turtle reproduction, said she had seen this individual a few years back, so it's definitely been hanging out in the creek and ponds. It makes me wonder if the hatchling I found earlier this Spring is the offspring of this individual. I am pretty sure there is at least another larger individual that lives in one of the ponds at the Emeriti Park as well.

As you probably know, Common Snapping Turtles are not a species you want to mess with. They are very aggressive out of water, and typically much more relaxed in water; however, even in water they can and will hurt you if it perceives you as a threat. Honestly, just don't touch these guys. There's really no safe place you can touch them, as their neck is extremely flexible and can reach just about anywhere on their body. If you see one, give it space.

Wednesday, September 3, 2014

A Nature Hike at The Ridges

This past Monday I co-led a trip to The Ridges with the Ohio University Wildlife Club, of which I am the secretary. This trip was a nature hike that was aimed at finding herps, finding insects, doing some birding, and basically looking at whatever else caught our attention as we made our way through The Ridges, which is on the outskirts of Athens. We had a much, much larger group than we expected (we had about 15 members show up but were honestly only expecting 5 or so), most of which were freshmen.

The Ridges
While up on the Radar Hill Trail earlier last week, I noticed a lot of Common Milkweed individuals. I thought it would be fun to fan out and search the plants for any caterpillars (especially Monarchs) that might have been chowing down.

Common Milkweed
Common Milkweed, Asclepias syriaca, is probably the most common milkweed species here in Ohio. The photo above (Taken at Rhododendron Cove SNP in Fairfield County) shows what they look like earlier in the Summer as they are flowering. I've previously covered Common Milkweed, and other milkweed species, in a post that you can read here. At the time of the trip up to The Ridges, the flowers were long gone and the plants each contained a few "seed pods," better known as follicles. These follicles contain many silk-like hairs that are attached to seeds. These silky hairs are known as pappus, which help scatter the seeds when they are caught by the wind. 682 acres of the land at The Ridges is actually set aside as a land lab where Ohio University faculty and students teach and conduct research. As a result, I'm pretty sure all these Common Milkweed plants have been planted there and did not just occur naturally. That is actually a very good thing, as I will get into here in a moment...

Monarch Butterfly Caterpillar
The main goal I had in mind, as I stated before, was finding Monarch Butterfly, Danaus plexippus, caterpillars. We fanned out and began searching the milkweed individuals for the caterpillars. A few minutes in, a voice called out exclaiming they found one. We all closed in to get a closer look at the nicely-sized green-white-and-yellow caterpillar. Monarchs are completely dependent on milkweed species for survival. Eggs are laid on milkweed, the caterpillars hatch and eat the milkweed, they metamorphose, then the adults mate and lay more eggs onto more milkweed and the cycle begins again. In fact, there are 4 generations of Monarchs a year. The overwintering adults migrate from Mexico up to the US each Spring and lay eggs; this is the first generation. Then, those of the first generation lay the second generation, and those lay the third. The interesting ones are the fourth generation. Unlike the first three generations, which die after laying their eggs, the fourth generation actually migrates over a thousand miles to Mexico. This migration happens in October. As for our individual, I'm pretty sure he (or she) is part of the 4th generation, which means after he metamorphoses in his chrysalis, he will begin his very long journey to Mexico to overwinter!

Monarch Butterfly Caterpillar
The milkweed the caterpillars consume isn't just important as a food source, however. Milkweed species contain a type of toxin known as cardenolide glycosides. Cardenolide glycosides in the plant are consumed by the caterpillars and stored, rendering the individual toxic to predators. After metamorphosis, they still retain the toxin, but they move much of it to the wings as some predators will attack the wings first. This toxin makes the wings taste very bad, and will also make the predators, namely birds, sick. Other species simply tear off the wings of butterflies and eat the body right away. As a result, Monarchs store the most potent toxin in their abdomen, which upon ingestion will make a predator quite sick. Although the Monarch individual might be killed, this will most likely ensure that predator will never again eat a Monarch, thus overall improving the chance of Monarch survival. The bright coloration of the adults warns predators of such a fate that might come from eating them. Monarchs aren't the only species to capitalize on this toxin; many other insect species which feed on milkweed are also toxic and brightly colored to warn predators of that toxicity.

Monarch Butterfly
An adult Monarch Butterfly from Pickaway County a few years ago.
Now, many people on the trip were surprised when I told them Monarchs are badly in trouble. As in "their population has declined by 90% over the last 15 years" badly. Yes, 90%. Their population, which had a high of over 1 billion overwintering individuals in 1996, was only 33.5 million in 2013. The average is about 350 million overwintering individuals a year. This decline is so bad that many are pushing to list Monarchs as threatened, a move I am for as well. So why the dramatic decline from 2012 on? Well, there are many factors. One is the 2012 drought which killed many. Another factor was the cold temperatures of the Spring of 2013, which slowed the growth of the first generation and messed up that year's schedule. Monarchs are also facing a severe loss of habitat in their overwintering grounds in Mexico, which is hurting overwintering survival. However, they are hurting for breeding habitat too. Monarchs require milkweed, and milkweed population has declined by about 60% in the last decade. This is due to many factors such as drought, new agricultural methods, and the mowing of roadsides (a favorite place for milkweeds to grow). As an aside, please consider growing milkweed on your property. Any bit helps. Anyway, all these factors have come together to decimate the population. You might have noticed that you haven't seen many, if any, Monarchs this Summer. That's not because you're missing them, that's simply because their population is that low right now. It's horribly sad, and if this trend continues their future looks very, very grim.

We also were able to relocate a deer skeleton that I stumbled across last Spring semester. I found a semi-decayed carcass in probably March or so, and the months following that had gotten rid of everything remaining but the bones. I led the group back along a small creek and had them look for any remains of the White-Tailed Deer, Odocoileus virginianus, among the tall boneset flowers. We scanned the area once and found nothing. We gave up and turned back to the main trail. A few seconds later someone called out they saw bones. I parted the 2-foot tall plants covering the area and saw a rib and some assorted bones. A quick search of the immediate area found much of the skeleton, including the skull and both jawbones. We decided to take those back with us to show others during the next club meeting. The photo above shows the skull with the jawbones in the place they would normally be.

As Alayna, the president of Wildlife Club, pointed out, the skull was quite small. She suggested it was a fawn. I looked at one of the jaw bones and sure enough it was a fawn. How can you tell quickly? Take a look at the photo above. Deer are just like humans; new teeth form and erupt as they grow through childhood. The photo above, which has one of the molars removed, shows another molar buried in the bone. A thin piece of bone partially covers the molar. Eventually, this bone would shrink back and the molar would erupt through the gum. You had the same exact process happen as your molars formed when you were young.

So just how young is this fawn? Well, the teeth give can help us find that out. I put the above photo together quickly to help explain. So, we know it is young, but is it a yearling (1.5 years+) or a fawn? Well, a yearling has 6 fully erupted teeth. This individual only has 5, so that means it is a fawn. So, how old of a fawn? Well, the first two permanent molars, M4 and M5, have erupted completely. This places the fawn in the 6 month to 14 month range at least. We can close this gap even farther by examining how far along the third molar, M6, is. In this individual, it has not begun to erupt yet, so that closes the range down to 6-11 months. The M6 molar is, however, close to beginning to erupt, so that puts it a little bit ahead of 6 months. As a result, I would age this individual at 9-10 months, +/- 1 month.

Overall, the nature hike was really fun and really productive. I will definitely do a few more this school year hopefully. Thanks for reading! I know this was a wordy post, but there's just so many interesting things to talk about. I could have gone on much longer, but I tried to keep it somewhat sane! Thanks again!