When it’s time to eat your own skin

Several years ago, I bought a couple hard polyethylene pond liners and dug two large holes in my clay and rock-filled back yard. I wanted to have a pond area and figured that two big tubs would be easier to manage and clean than maintaining an in-ground pond. So far, that has been the case except for the fact that I couldn’t keep any fish – a great blue heron managed to eat all the fish I had over the course of about 2-3 years.

That doesn’t mean my pond is not populated, however. Indeed, all the water sources in my yard have residents. Some are unwanted – for example, the mosquito larvae that I admittedly kill with mosquito dunk. The Cope’s gray tree frogs (Hyla chrysoscelis) have a preference for my rain barrels. Somehow they manage to crawl inside even when a lid is on and they deposit hundreds of eggs per season.

   

Fortunately, not all of the frog eggs hatch or my yard would be overrun and the sound in the evenings would be overwhelming. Even the half-dozen or so current adults manage to produce quite a loud concert series – I’m surprised neighbors haven’t asked me to do something to tamp down the sound!

I used to have bullfrogs in my container ponds but haven’t seen them this year. Instead, my neighbors have been lovely green frogs (Rana clamitans). One grew to a very large size and he was joined by two others of a bit smaller stature.

They aren’t very noisy, mostly croaking in the late afternoon. It must have been that sound that attracted another neighborhood resident whom I spotted one day sitting on a nest box next to the pond. The red-shouldered hawks (Buteo lineatus) have spent time watching the pond before when in the mood for frog legs; this was a young hawk who had obviously been in the pond as evidenced by his wet plumage.

The pond was quiet for a few days and I thought the hawk must have had a good meal. And then, slowly, the frogs began to emerge again. There are three that sit on the rocks surrounding the larger pond although one is a bit smaller. This makes me think the hawk might have gotten one but that a juvenile frog was now accompanying the larger pair.

   

When my pond “greenies” croak, they don’t seem to get very large inflated vocal sacs. At the NC Botanical Garden, fellow photographer Mary showed me a green frog that she had been photographing and he croaked a couple times. It went too fast to get a good shot so I offered to make him “talk” by croaking at him. My pathetic attempt at imitating him really was quite pitiful, but amazingly did evoke a response. His vocal sac didn’t get really large either though.

One day, I spotted one of the yard frogs sitting on a rock, opening and closing its mouth without making a sound.

 

When I looked more closely, it seemed to have some membrane hanging on its side.

Then I saw that it was partly in the frog’s mouth and the amphibian was tugging away at it. I wondered if he was sick.

It turns out that he was perfectly healthy and staying that way by eating his own skin! These amphibians regularly shed their skin because it would otherwise harden and make it difficult for them to absorb oxygen while underwater, where they spend a considerable amount of time. So periodically, they scrunch themselves together and then stretch to break the skin so that it can be pulled off, leaving supple skin behind to better enable the “breathing” method called cutaneous gas exchange.

But why do the frogs then eat their skin? It actually has many nutrients, including calcium and proteins. I have no idea if the skin has any taste and whether they enjoy ingesting it. It seemed to be a bit of a laborious process when I watched this frog go through the process. Added to that is the fact that they actually use their eyeballs to push food down their throats and you discover that our froggy friends have quite a unique digestive process!

 

Outside my yard, I’ve not seen too many frogs this year. There was a lovely little Northern cricket frog (Acris crepitans) out and about on one of my walks.

More recently, I’ve been seeing Fowler’s toads (Anaxyrus fowleri) in the woods and parks.

 

     

At the NC Botanical Garden, I had the chance to see some rather large tadpoles sharing a pond with smaller ones.

It was interesting to see that the tadpoles first develop their hind legs and then their front legs before eventually losing their tails.

Finally, one more type of interesting creature I’ve been observing lately on walks are land snails. They don’t really belong in a blog that is about amphibians but it’s unlikely I’ll be writing one about mollusks any time soon. So, I’ll leave you here with a few photos of what I thought were some snails with beautifully spiraled shells. Have a good day or evening!

 

 

 

My pond and the cycle of life

Undergoing cardiology exams can bring up thoughts of mortality and a life lived; perhaps they also made me more attentive to the cycle of life in my yard, particularly in the vicinity of my backyard pond.

Several years ago, a local garden center went out of business and they had a 175-gallon black plastic pond for sale. It was a good deal, so I invested in it and then had to dig a large hole in the rocky Piedmont clay ground of my backyard (with a bit of help from a neighbor teen). At a certain point, the ground was so hard we couldn’t penetrate it with shovels so the pond now sits a bit above ground level; the rocks I piled up around it have offered a home to Eastern chipmunks (Tamias striatus).

 

I transferred some of my beautiful koi and goldfish from a smaller pond, only to have a great blue heron (Ardea herodias) come by to clean them all out.

On the recommendation of the garden center staff, I had positioned a heron statue by the pond – they said herons don’t like competition, so the intruder would keep flying when s/he saw the one by the pond. It didn’t take long for the bird to figure out the stationary bird was not real, however.

After the heron had eaten all the koi and goldfish, I still had some tiny baby fish. At first, I thought they were from my now deceased koi but apparently the intruder heron had had fish eggs on its feet from a nearby natural pond and left them behind. So for a time, I had unidentified native fish in the pond. They were extremely shy, however, and I only got a brief look at them when they surfaced early in the morning; as soon as I came near, they dove down under the water plants (no good photos).

Then some green frogs (Lithobates clamitus) moved in this past summer and ended up being extremely prolific reproducers. Before I realized it, there were at least 500 tadpoles in the pond!! They were eating the fish food and at the same time I noticed that I wasn’t seeing the fish at all anymore. Going online, I found out that tadpoles will eat fish – their sheer numbers had to have spelled doom for the fish.

 

 

I collected lots of the tadpoles, gave some to a friend for her water feature and released hundreds into the local creek (they are native animals after all). A few of the tadpoles grew into frogs and the pond became a residence for some very loud croakers.

 

  

The next chapter in the story came a couple days ago. I had seen a pair of red-shouldered hawks (Buteo lineatus) visiting my yard recently. I thought they were after the chipmunks, numerous squirrels and songbirds populating the area. The other day, however, one hawk took up a position in the crepe myrtle tree next to the pond and just sat there calmly not bothering with any of those creatures. Numerous Northern cardinals (Cardinalis cardinalis) perched in the tree above her and many other species of birds were at the nearby feeders;  none of them were concerned at all with the hawk’s presence. The squirrels didn’t seem perturbed either.

She sat fairly still and I took some photos through my kitchen window. Then I ventured out into the backyard, sure she would take off as I left the porch steps. But Ms. Hawk just sat there, sometimes stretching a leg or engaging in a little grooming.

     

   

Occasionally, she looked up but often her gaze was fixed on the area around the pond.

She would stare intently down at the ground – I thought she might have spotted one of the pond chipmunks.

Then after a while, I noticed her shifting her stance – suddenly she plopped down into the pond with spread wings. It happened too fast for me to get out from behind dried plants to get a good photo, so I watched as she climbed out of the pond. Then it became apparent what she had been hunting – she had caught one of the green frogs.

  

It looked like she bit its head to kill it as soon as she got on dry land; the frog wasn’t moving.

Then she spent time ruffling and shaking out her feathers which had gotten a good soaking.

She spent a little time looking around and then abruptly took off with her prize, closely followed by another red-shouldered hawk who suddenly swooped in.

He chased her but she got away with her meal and he ended up sitting in a neighbor’s tree, somewhat disgruntled with his failed thievery attempt.

  

Ms. Hawk returned yesterday and spent quite a bit of time in a high tree surveying the yard and gazing down at the ground. Red-shouldered hawks sometimes eat birds, such as sparrows, doves and starlings (which are all numerous around my feeders) but more often they go after snakes, mice, toads, frogs, lizards and small mammals such as voles and chipmunks. They will also eat insects and earthworms. Since I’m leaving the leaf litter, there are undoubtedly more insects hiding there than in neighboring yards. I’m not sure what Ms. Hawk is seeking in my yard, but I hope she doesn’t get all the pond frogs. In any event, I’m sure new ones will find the water in the spring and in the meantime, I have a beautiful bird of prey to watch this winter.