The first ice of the season on the Wetlands.

The ice will soon be history, all gone. I, or we, know that the ice will be gone within a day or two since the TV, internet, and radio tells us these things ahead of time. But for some of the creatures that live in and depend on the Wetlands for food, ice is not a good thing and it can’t be predicted when it will go away. The kingfisher who needs to dive into water to catch fish, the heron, egret, mergansers, and others don’t know when the ice will melt. Should they move on, or wait it out?

The birds can afford to hang out for a few days to see what will happen, after all, they have wings and can move to bigger water if things don’t improve. They can be at Falls Lake in minutes and there are many other local ponds that are a bit deeper than our Wetlands and which may not freeze as quickly.

A frozen shiner.

The photos that you see here were taken on January 4th and show some of the birds who decided to stick it out long enough to see if the water would open up for them.

But first, some of the shiners which have been huddled up in a shallow corner of the Wetlands for nearly a month now did not fare well. However, most of them, the ones not yet eaten by the birds that you see in the photos, are still splashing around in the water and have actually kept a small bit of water open because of their thrashing about.

The Great Egret (below) is probably the same bird seen in the Wetlands on the 22nd of December (it was also seen on the 24th).

The new addition to the Wetlands, a Great Egret, rests while the ice melts.

This egret is more people tolerant than its larger relative, the Great Blue Heron, and allows for a closer approach.

A closer look at our new friend.

Kingfisher and GBH decide to stay and see what happens.

The hawk looks over its shoulder at some, unheard by me, noise coming from behind.

One of the local Red-shouldered Hawks has resumed its hunting strategy of sitting quietly in the willows watching for the slightest movement to pounce on any unsuspecting frog, tadpole, shrew, or rat.

Despite the cold, it was a good day to be outside.

By the way, it may reach sixty degrees by the end of the week! Are you going to be sitting inside reading blogs about nature, or outside experiencing some of the things those blogs speak about?

In August I wrote about a pile of crayfish hatchlings that I found on the path in Explore the Wild. I also wrote about how those crayfish are not native to our area and how they may be completely changing the Wetlands.

The crayfish that I see and capture in our Wetlands are Red Swamp Crayfish (Procambarus clarkii). I first noticed these large crayfish with the red claws a little over two years ago. Then, it was unusual to see, let alone capture, a crayfish in our little Wetland. A typical haul in a hoop net would include dragonfly and damselfly nymphs, diving or water scavenger beetles, a variety of beetle and fly larvae, scuds, freshwater clams or mussels and various other aquatic invertebrates, and perhaps a tadpole of one of the 13 species of frogs and toads that I’ve recorded here. A crayfish was unusual.

Red Swamp Crayfish.

On a recent Saturday (10/15), Ranger Kristin and I were down in the Wetlands scooping through the water with a long handled net. We were after crayfish. Nearly each dip into the water with the net brought in a crayfish. I think we missed only once or twice. Several times we brought in 3, 4, or 5 crayfish. The crayfish varied in size from half inch juveniles to about two inches in length. Although we also caught many backswimmers (Notonectidae) we only caught three dragonfly nymphs and no, that’s zero, damselfly nymphs (not a good sign). And although we did catch a Water Scorpion, we caught very little of anything else.

Besides the quantity of the catch, the quality of the water itself is not as it was in the past. The turbidity of the water (water clarity) and the submergent and floating vegetation has changed considerably. A picture of the edge of the Wetlands taken in May of 2010 shows both clear water and much vegetation.

The water near the edge is about a foot or more in depth. The submergent vegetation stretches across the entire pond. The white area in the center is a mass of Bullfrog eggs.

In the above photo, the water is a foot or more deep at the edge of the vegetation. The bottom is clearly visible. Currently, the bottom cannot be seen in six inches of water. The water will no doubt clear up a bit with cooler temperatures later in the season, but this summer was the worse that I’ve seen. Why is the water more turbid now than before?

Wait, before we get into the water quality, a little background info. Historically, the Red Swamp Crayfish is native to Texas, Oklahoma, Arkansas, Missouri, Illinois, Kentucky, Tennessee, Louisiana (crawdads), Mississippi, Alabama, and Florida. They are now in at least 16 other states including Hawaii. And, they can be found on nearly every continent from Asia to Europe and from Africa to South America.

These large red-clawed crustaceans were purposely introduced for human consumption as food to most locations outside of their natural range. Once there, they either walked, swam, were dumped by fisherman (they’re used as bait), or were discarded by amateur aquaculturist who no longer desired to keep them in their aquariums as pets.

Crayfish in general eat just about everything they can get there claws on. Primarily detrivores (eaters of decaying organic matter), they will consume whatever is available, which includes plants and animals. They don’t simply browse on the plants that they eat but cut the plants off at the roots discarding what they don’t eat (important). They consume snails, aquatic insects and their larvae, fish and tadpoles and the eggs that they came from…but you get the picture, they eat everything.

Now, back to the water quality. In a study done in Japan, “Contribution of bioturbation by the red swamp crayfish Procambarus clarkii to the recruitment of bloom-forming cyanobacteria from sediment,” Yoshimasa Yamamoto writes:

“…results of this study suggest the potential influence of crayfish-associated bioturbation on the dynamics of cyanobacteria in the Hirosawa-no- ike Pond where the recruitment of cyanobacteria from the sediment is assumed to be especially important in the formation of cyanobacterial blooms.”

In other words, the crayfish, through their daily routines of burrowing and just moving about and feeding, stir up the bottom sediment releasing bacteria which causes blooms of that bacteria, also known as blue-green algae, which would not happen if the crayfish were not present.

How does the turbidity affect the Wetlands? Besides the result of making it more difficult for herons, kingfishers, and fish eating mergansers to see their prey, the algal bloom can potentially deplete the water of its dissolved oxygen making it difficult for the prey itself to survive in the water. And, there are many organisms that share the pond that also need oxygen, like some of the macro inveterbrates and aquatic vertebrates mentioned earlier. Blue-green algae is not a good thing.

A Bullfrog happily sits among the submergent vegetation of the Wetlands. The light colored "dots" on the surface are frogbit, another non-native species, this time a plant.

Submergent vegetation is typically rooted in the bottom of a pond or stream and grows completely below the water’s surface, it is submerged. There currently is no submergent vegetation to be seen in the Wetlands. Submergent vegetation is important to the survival of many aquatic invertebrates that use the vegetation as both food and shelter. It’s also used as food for larger animals like ducks and geese and as shelter for tadpoles and fish. The submergent vegetation is gone.

Where did the plants go?

In a study done in Kenya “Feeding of the exotic Louisiana red swamp crayfish, Procambrus clarkii (Crustacea, Decopoda), in an African tropical lake: Lake Naivasha, Kenya” the authors said:

“It is concluded that P. clarkii could well have accounted for the observed elimination of native plant species in Lake Naivasha;” 

As mentioned earlier, crayfish are omnivorous, they eat it all, including plants. But instead of browsing on the plant, allowing those parts that were browsed upon to grow back, the crustaceans cut the plant off at the roots, eat what they want and discard the plant. The discarded plant may very well end up being their next meal, this time as detritus (decaying organic matter) but the damage is done, the entire plant and its use as a shelter and food for other creatures is history. It’s like cutting down the tree to get at the walnuts.

There are many other studies which attest to this crayfish’s ability to completely alter a pond or wetland. I’ve quoted but a few. Our Wetland here at the Museum of Life + Science is unquestionably different than it was just a year ago. We are catching fewer species of all aquatic life (except crayfish) in our sample nets, the submergent vegetation that used to reside in the Wetlands is gone, and the turbidity is up.

Check this link to see the clarity of the water in the fall of 2009 as a grebe swims around catching fish, tadpoles, and crayfish. Scroll down the photos. In one image, the grebe’s shadow can be seen on the bottom in about two feet of water. You’d be lucky to see it’s feet today.

The water next to the plants is about 8 - 10 inches deep, the bottom can not be seen. That's smartweed on the left, another new addition to the wetland's.

I found very few Green Treefrog young in the vegetation alongside the Wetlands this summer where typically I could locate half a dozen on any given day in July or August. True, the dry summer could have had an effect on the numbers of treefrogs, but earlier in the summer there were plenty of adults out breeding.

I didn’t see any bullfrog egg masses in the water this past summer. It’s possible that I simply missed both the treefrogs and bullfrog eggs, but I usually keep an eye out for such things. Perhaps the open water situation left the eggs open to predation. Had there been any bullfrog eggs deposited this summer they would have been exposed from below.

The various species of frogs have different egg laying strategies. Some, like the bullfrog above, lay their eggs in sheets on the surface. Some frogs deposit eggs in masses attached to a twig or submergent plant stem. Others drop the eggs in the leaf litter on the bottom of the pond. The water’s surface is open from below without the submergent plant cover, which also means that there are no plants in the Wetlands to lay eggs upon for those species that use that method of egg deposition, and the leaf litter has all but been eaten by the crayfish, at least in the open water areas of the Wetlands. It’s not all doom and gloom though, there are still many areas among willows and some of the emergent plants, like the rushes, where frogs can lay their eggs they way that they need to.

Once these crayfish enter a wetland they’re very difficult to get rid of, if that’s what’s desired. I read one report where the pond in which the crayfish had colonized was bleached. You can search for more info about the bleaching event on the internet just by typing bleached Wisconsin crayfish. I don’t think we want to bleach our wetland.

This past summer we had a Yellow-crowned Night-heron stay with us. Yellow-crowns eat crayfish. Maybe a breeding pair or two will take up residence here at the Museum next year and work on lowering the crayfish numbers. The resident raccoons, who also eat crayfish, don’t seem to be able to keep up with the prolific decapods.

While the crayfish are here it may be a good idea to test them for retention of heavy metals and other pollutants in their muscles.

After, and if, they are cleared of any pollutants, we should set out traps, catch a mess of the little mudbugs and have a big Crawfish Boil on the Wetlands Overlook. And in Texas.

A Solitary Sandpiper feeds just off the boardwalk in Explore the Wild.

Solitary Sandpipers are one of three “most likely to be seen” shorebirds on the list of species here at the Museum, along with Spotted Sandpiper and Killdeer. Our Wetlands is simply not conducive to shorebird feeding, not enough open mudflats. Even in dry years like this one there’s no guarantee that one of the trio mentioned above will show up in our rather small habitat.

Needless to say, I was excited to see our little friend. After watching the sandpiper for several minutes I noticed that other eyes were studying the bird as well.

It was a Bullfrog and it was stalking the sandpiper.

The frog in this photo is clearly stalking the bird. It was crawling commando style towards the shorebird.

A little too close, if you ask me.

Several times the frog got quite close to the bird. But each time the bird would simply walk away in the opposite direction, creating what it considered a safe distance between itself and the frog.

The stalk-and-walk continued for perhaps ten minutes while I shot photo after photo waiting for the inevitable leap at the bird.

The bird seemed to take it all in stride, but I was getting anxious. Leap, frog! Leap!

Finally…

The frog crawled close to the bird one last time and...

SPLASH!

The frog missed. You can see the bird’s reflection and shadow in the upper right corner of the photo above.

The bird momentarily hovered above the frog, all the while protesting loudly at its inconvenience. The indignant frog hopped off to deeper water to lick its wounds.

The bird watches as the frog (far right) tries to forget.

The frog originated its stalk near the grass at bottom left. You can clearly see its tracks in the mud as it slowly crawled along.

The frog had stalked, crawled on its belly, a dozen or more feet only to fail. The frog must have been in a desperate state to try such a maneuver.  From where I stood, it was certainly interesting to watch. Although I’ve heard stories and seen depictions of bullfrogs capturing birds, mostly warblers, I’ve never witnessed it myself.

Bullfrogs are stimulated by the movement of potential prey. It’s the movement that draws their attention and triggers the lunge at the prey. If the prey doesn’t move the frog will most likely ignore, or may not even see, the prey.

Potential prey is anything that is of reasonable size, the same size or smaller than the frog itself. I’m told, however, by Ranger Kristin, that a relative of her’s once witnessed a bullfrog take a stab at a pigeon that was drinking by the edge of a small pond.

I would think a pigeon too large to swallow. But from what I’ve seen bullfrogs eat here in our Wetlands, everything from insects, to other frogs, to the whopping crayfish we have here, I don’t doubt that a large bullfrog would consider a pigeon fair game. Besides, who would make up such a story!

The gruesome part of the story is that the frog was only able to secure the head of the pigeon. How it did that I don’t know since frogs don’t chew or tear food. They grab, swallow, and digest. But, and this is an important but, they don’t easily let go of something that they latch onto. The pigeon must have struggled tremendously. It’s a good thing that frogs don’t grow as large as, say, a Labrador Retriever.

And voila, another Solitary Sandpiper showed up!

A pair of Solitary Sandpipers feeding together.

The two sandpipers fed peacefully alongside on another for several minutes.

Wait a minute, who are you?

And then, as if suddenly realizing that they were both “Solitary” Sandpipers, they began chasing one another, drawing lines in the sand, or rather, mud. One bird seemed to be the chasor and the other the chasee. Curiously, the chasee would fly out over the water after being charged at by the chasor, and would land back where it had started only to be chased off again. This behavior went on for about fives minutes until one of them flew off to land on a boulder on the other side of the Wetlands.

Towards the end of the day they were both seen happily, or at least passively, feeding together.

The two shorebirds cautiously watch as a turtle swims by (right). Probably a good idea considering the earlier encounter with the frog.

I’m not sure which of the two birds had the run in with the frog, but I’ll bet it’s the one with the outstretched neck (above).

What fun, to watch these two birds! The following day, both were gone.

Yellow-crowned Night Heron (5/28/11).

I thought I’d go down to the Wetlands early (relatively early) to see if the night heron that showed up yesterday was still around. At first I thought that the bird had moved on, until I checked the secondary Wetlands Overlook (near the Lemurs). It had rained 3-5 inches the day before and there weren’t many exposed areas in the swamp for a night heron to hunt from, but the bird had found one on the back side of the Wetlands.

When night herons hunt they typically move very, very slowly so as not to scare the prey, which is usually crabs, crayfish, and other small invertebrates. As the bird moves close enough to the prey to strike, it does so with a quick lunge catching the prey in its open bill. I’ve watched these stealthy herons hunt for fiddler crabs on a mud flat for hours, slowly stalking the little crabs and then swallowing them down with little hesitation.

Waiting for a big, crunchy crayfish to walk by.

Our visiting yellow-crowned is not quite in full adult plumage, which can take two years to achieve.

Perhaps this heron will stay a while longer, although I’m doubtful. We have no crabs in our Wetlands. But, we do have a fairly healthy population of crayfish, and certainly many frogs so hopefully I’ll be wrong about how long the heron is with us. We’ll see.

Not a night heron, but a Gray Catbird. This bird came over to see what I was so intently watching in the swamp. Never pass up an opportunity to get a photo when one presents itself.

A pair of Hooded Mergansers rests and preens on a rock in the Wetlands.

The latest that I’ve observed Hooded Mergansers in the Wetlands was April 10 back in 2009 when a lone female was seen taking off from the water of the Wetlands, circled to gain altitude and left for points unknown. Typically, they leave by the last week in March. There have been 10-13 individuals in the Wetlands for the past several weeks, mostly females. There are three adult males and at least one male in immature plumage.

The pair in the photo above is often seen away from the other mergs. What does that mean? I hope it means that they’re going to stay and nest in the nest boxes placed in the Wetlands for just that purpose.

Meredith and the owl, Christopher.

Both the owl and the hawk are birds which were injured in the wild and whose injuries are such that they can not fend for themselves. They can’t be released back into the wild. Both are used for educational purposes here at the Museum.

Anna and the hawk, Misha.

The "far side" box is located on the far shore of the Wetlands, opposite the main Wetlands Overlook.

We’ve been discussing the installation of Wood Duck boxes here in the Wetlands for some time. Two such boxes were installed on Wednesday. While the nest boxes were built for Wood Ducks, the hope is that the Hooded Mergansers that frequent the waters of the Wetlands during the winter months will stay and use one of the boxes next spring. Normally the mergansers leave us in March for points north where they nest along small lakes, ponds, and marshes.

It’s entirely possible that Wood Ducks will use the boxes, which would be welcomed, but I’m hoping that the mergansers will decide to stay and attempt to breed. Since they don’t normally nest in our area, it would certainly be be exciting if they did decide to nest here. I would be just as happy, though, if Wood Ducks or even Screech Owls, used the boxes. I’d love to watch any one of those birds raise their young here in Explore the Wild.

Robin Dale (formerly of the Butterfly House) decided that on her last week here at the Museum she would volunteer to help with the installation of the nest boxes. Robin has a fondness for mucking around in the Wetlands, which is a good thing if you’re planning to install nest boxes for ducks in a wetland.

Jim Phillips and Jose (Exhibits/Planning) hand the nest boxes down to Robin Dale and Taylor (Exhibits/Planning) who wait patiently in the water next to the boat.

Robin and Taylor walk the boat with the nest boxes over to a small island in the Wetlands. Both appear to be enjoying themselves.

Robin and Taylor install the "island" box with no trouble.

The island box.

We still need to trim back some branches around the boxes, and install predator guards, but the boxes are up and I’m excited!

With two nest boxes in the Wetlands, the birds have a choice between two slightly different locations. I’ll keep you posted on any new developments.

Thanks goes out to all who had a hand in getting this project going, from start to finish; Michele Kloda, who did most of the leg work and who actually went out and purchased the nest boxes, the men who helped install the boxes (Jim, Jose, and Taylor), Joe Nucilli (formerly of facilities, and one of the hardest working people I know) who did most of the prep work on the boxes, and especially to Robin, who didn’t have to take part in this adventure but volunteered for one last trudge through the Wetlands because she “likes going into the Wetlands.” We’re going to miss you around here, Robin.

Have a good one!

The boardwalk sees little sun at this time of year. What sun the boardwalk does get is filtered through the trees.

A light cover of snow over the frozen Wetlands.

Ursula rummages around in the snow for a snack. Typically, it's the other four bears that are up and about, but they were all taking a snooze this morning when this picture was taken.

Enjoy the snow while it lasts.

The Wetlands, very quiet.

Virginia contemplating her next move.

Yona (foreground), reacting to Virginia's next move.

Come out and have a look!

Though the pond has had ice on it for the past week and a half, there has been at least a few patches of open water. It's now frozen solid, or is it?

The Hooded Mergansers have taken flight for larger bodies of water. I’ve seen the Belted Kingfisher fly in each day to inspect the pond for open water only to leave frustrated, its loud, raucous rattle filling the frigid air. The Great Blue Heron has stuck it out, staying on the fringes of the pond where it might find a small patch of open water. Is there any open water, any food left to be had by the kingfisher and the heron?

Halfway between the end of the boardwalk and the main Wetlands Overlook there is a very small bit of water which is not frozen. There’s a pipe just below the surface which drains the area above and across the path from this little patch of the Wetlands. There are hundreds of tadpoles in this tiny piece of water, Bullfrog tadpoles!

Some of the tadpoles which seem to be thriving in the Wetlands.

The water at times boils with the tadpoles as they swim about and surface for a swallow of air. Being bullfrog tadpoles, they take at least a year to morph into frogs, and they overwinter as tadpoles. Some are eaten by the local kingfisher, herons, and mergansers, when they can get to them.

A tadpole gulps for air as another (just above it) rolls away from the surface.

Brave the cold and stop by to give a look at the tadpoles. You may see me out there watching them.

Flowering Dogwood.

Tulip Poplar

Redbud.

White Oak.

Through the trees.

The woods.

Red Maple.

Black Willow.

Among the pines.

Some reflections.

The Wetlands.

A Willow.

Willow branches.

A Hooded Merganser drifts past the willows.

Changes occur quickly at this time of year so head out to Explore the Wild and watch it happen!