August 28,  2011

SPARROW-SIZED KINGFISHER
North America's Belted Kingfisher is about 12 inches long (31cm). On Wednesday morning at a pond fringed with Sawgrass, near the mangroves, a kingfisher about the size of a House Sparrow -- only five inches long (12.5cm) -- alighted on a nearby twig, as shown at https://www.backyardnature.net/n/11/110828ki.jpg.

Throughout the Yucatán two kingfisher species commonly occur, the Green and the Pygmy. This was the Pygmy, CHLOROCERYLE AENEA STICTOPTERA, distributed from southern Mexico to Ecuador and Brazil. The Yucatán's other kingfisher, the Green, also is much smaller than the North's Belted, being only eight inches long (20cm). The Pygmy's throat is rusty colored, though, while the Green's is white, so in the field they're easy to distinguish, even when their relative sizes are hard to judge.

Up North you've probably watched Belted Kingfishers dive for fish, spectacularly splashing into the water. The Pygmy dives with a dainty little kerplunk.

The bird in the picture didn't seem at all bothered to have me ten feet away snapping pictures. In fact, I had to noisily scrape my feet to get her to turn her head for a profile view showing the beak. In this species the female wears a narrow, green chest-band, while the male doesn't. Our bird only watched for prey in the pond water three feet below, but I read that at times Pygmy Kingfishers catch insects flycatcher-like.

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WOOD-RAIL
While standing hoping to see the Pygmy Kingfisher dive for something, movement on the right had me turning on and raising the camera before I knew what I was focusing on. You can see what materialized before me at https://www.backyardnature.net/n/11/110828rl.jpg.

About the size of a normal chicken and shaped like one, too, except for that long beak, it had to be a rail, and rails are usually thought of as hard to see. It wasn't the North's Virginia Rail -- which does occur as far south as Guatemala but not in the Yucatán -- because it lacked that species' conspicuous black and white, Zebra-like barring across the lower belly. It was a rail species not found in North America: the Gray-necked Wood-Rail, ARAMIDES CAJANEA. And that bird is about as handsome as you can ask a bird to be, especially when it appears unannounced in such a pretty setting, it's red legs and eyes, and orange/yellow beak, simply refulgent against a pond's placid, green water.

Gray-necked Wood-Rails are distributed in swampy woodlands, marshes near woods and mangrove edges from eastern Mexico to northern Argentina. My impression is that the species isn't as shy as Virginia Rails. Back in the 70s several Gray-necked Wood-Rails used to hang out in a shallow pond in the Maya ruins of Tikal in northern Guatemala, right beside the main trail between the entrance and the big pyramid. Year after year the birds didn't seem to mind when Northern birders clustered around the pool watching them and snapping photos.

Marcia says that at certain times of the year wood-rails are commonly seen visiting our compost area.

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OVERWINTERING SHOREBIRDS ARRIVING
Just a month ago in the July 24th Newsletter I was commenting on how empty our beach was of shorebirds. Why weren't sandpipers, plovers and the like feasting on the mind-boggling abundance of springtails living among our endless miles of washed-up seaweed?

The week afterward, a few plovers showed up. This week the numbers and diversity of shorebirds is about double that of last week. Clearly, they're beginning to return. You can see a typical view of a mixed flock of Semipalmated Plovers and Sanderlings at https://www.backyardnature.net/n/11/110828x9.jpg.

As I took that picture, a small flock of Ruddy Turnstones and a single American Golden Plover stood nearby. All these species nest in the far north, on the northernmost shores of Canada and Alaska, so maybe up there it's already wintry.

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NEW KITE, NEW PIGEON
Besides shorebirds, the wood-rail and Pygmy Kingfisher, other birds are magically appearing for the first time this season. For instance, on Friday for the first time at this location I saw what's shown at https://www.backyardnature.net/n/11/110828kt.jpg.

At first I thought he was a Mississippi Kite, which does migrate through Mexico to its wintering grounds in South America. However, the migration route within Mexico passes south of the Yucatán. What's in the picture is the similar looking White-tailed Kite, sometimes called Black-shouldered Kite, ELANUS LEUCURUS MAJUSCULUS. In the field the species' black shoulders most easily distinguish it from the Mississippi Kite, which has grayish shoulders. White-tailed Kites are permanent residents in open country with scattered trees, marshes and irrigated agricultural lands from the US Southwest to central Chile and Argentina.

Just a few days earlier, also perched on a dead snag in the mangroves, a White-crowned Pigeon, COLUMBA LEUCOCEPHALA turned up, but it flew away before having its picture taken. White-crowned Pigeons occur in the Caribbean and adjacent areas of Mexico and Florida, wandering to mainland coasts from Honduras to Panama. In A Guide to The Birds of Mexico and Northern Central America, Howell says that the species is known to breed only on islands, but commutes to/from the mainland to feed, sometimes leaving certain islands for the winter. "Seasonal movements need study," he says.

So, these are fun times for birders in this part of the world. Not many studies have been accomplished here, so just about any observation I make probably will make someone happy, someday.

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PANTING GRACKLE
In mid afternoon when there's little breeze sometimes Great-tailed Grackles quietly rest panting in the shade of palm fronds level with my upstairs porch, as at https://www.backyardnature.net/n/11/110828gk.jpg.

Birds don't sweat, so they keep cool by staying out of the sun when they can, and they pant, letting cooler air carry heat away from their moist lungs. They also flutter their throats, expelling heat from the rich tangle of heat-carrying blood vessels there.

Birds can also raise their feathers and hold their wings out for air circulation, plus they have a few other tricks.

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GULF COAST TOAD BENEATH THE NIGHTLIGHT
At dawn, beneath the light that had burned all night outside the dining room, a toad sat waiting for moths disoriented by the light to crash to the ground beaten and exhausted. It was the classic spot for toads wanting an easy meal. You can see this toad at https://www.backyardnature.net/n/11/110828to.jpg.

That's a Gulf Coast Toad, BUFO VALLICEPS. We've often met them, but they vary in appearance. It's a good idea to add this image to our various shots, online at https://www.backyardnature.net/mexnat/gulftoad.htm.

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RED ON YELLOW, KILL A FELLOW...
At 9AM on a certain morning I was biking the white sand road along the beach when I met what's shown at https://www.backyardnature.net/n/11/110828c2.jpg.

When you see any cross-banded, red, black and yellow snake you're supposed to think "coral snake." And you know that coral snakes are deadly. But you also know that coral snakes generally are nocturnal and, more importantly, the vast majority of cross-banded, red, black and yellow snakes people come into contact with are perfectly harmless mimics of coral snakes. However, there's a little folk rhyme to help us separate the real corals from the mimics. It goes like this:

Red touches yellow,
You're a dead fellow.
Red touches black,
You're OK Jack!

In other words, if the snake's red bands are framed with narrow, yellow bands -- as in our picture -- it's a real coral. The more commonly encountered and harmless Tropical Milksnake looks just like a coral snake, except that its red bands are framed with black ones.

Actually, that rhyme works only in North America. Down here I've seen some coral mimics with red touching yellow. However, all the real corals I've seen do have their red touching yellow, so, so far, the rhyme works that way.

Our road-crossing snake was the Variable Coral Snake, MICRURUS DIASTEMA. It's very similar to the Eastern Coral Snake, Micrurus fulvius, of the US Southeast, and the "Texas Coral Snake," M. tener, which we met in Querétaro, and which is still on exhibition at https://www.backyardnature.net/q/coral.jpg.

In fact, I don't see any difference between these three species. It's just that experts say that they're different, and that what's in Querétaro is the "Texas Coral Snake" (though it's mainly a Mexican snake), and that what we have here is the Variable.

This is the first venomous snake I've seen at this location. And I was surprised to find a mostly nocturnal coral snake crossing a sun-drenched, white-sand road at 9AM. In the picture he's shining as if he's still wet, so maybe he was evacuating the mangrove swamp as it slowly continues to fill with water. He was traveling in the right direction for that.

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A COLORFUL TIDE-POOL RIM
When the tide goes out, tide pools form at the rocky points. Sometimes interesting organisms show up in the pools, so I like to visit them, often just sitting for long periods gazing into the waters.

During one low-water visit when I stepped across a bathtub-size pool I noticed what seemed to be a granular crust formed at the pool's edges. My first impression was that tar from oil pollution had gathered at the pool's edges and now small seashells were sticking to the tar. You can see what I saw at https://www.backyardnature.net/n/11/110828hb.jpg.

Up close I saw that they were indeed shells, mostly nerites -- which are marine snails -- of many sizes, colors and shapes, but there was no tar. The shells appeared to be self-gathered, as shown at https://www.backyardnature.net/n/11/110828hc.jpg.

Many of the shells were moving, but not with smooth, flowing motions typical of snails. They moved jerkily, as if on wobbly legs. I picked up one shell, put it on my hairy knee, and the source of this mystery at https://www.backyardnature.net/n/11/110828hd.jpg.

No snail this, but a hermit crab, a different species from the big ones so commonly seen crossing roads and sandy backyards here. Volunteer identifier Bea in Ontario pegs it as the Mexican Blue Legged Crab, CLIBANARIUS TRICOLOR. It's distributed from Florida and the Bahamas throughout the Caribbean, and as such goes by other English names as well, including Tricolor Hermit Crab, Equal Handed Hermit Crab, Blueleg Hermit Crab, and Dwarf Blue Leg Hermit Crab. The word "dwarf" in the last name reflects that this is a small crab, reaching only about 4/5 of an inch (2cm) in size.

Mexican Blue Legged Crabs are "detritivores," which means that they eat dead plants and animals, or detritus. It also sifts through the sand, "cleaning" it, as it feeds on algae, cyanobacteria and seaweed.

But all this doesn't explain why those thousands of crabs carrying all their varied borrowed shells formed such a crust at the edge of that particular pool. I could find no similar gatherings at other pools.

On the Internet I find a research paper reporting "clustering behavior" among Mexican Blue Legged Crabs in The Bahamas. Those researchers found that individual crabs in a cluster don't always stay in the same cluster, but might move around. However, explanation is given for why the crabs cluster to begin with.

Once again I'll just park this information and the pictures on the Internet, and hope they'll be useful to future students and naturalists.

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URBANUS SKIPPER UNSPECIFIED
Here's a story about how hard it can be to identify certain things. But first, a little background info:

As is typical of harsh environments such as our salt-saturated, low, narrow sand ridge between the Caribbean and the mangroves, species diversity here is low, but the species present often are endemic or otherwise unusual because of their special adaptations to the inhospitable environment. Therefore, butterfly watching here this summer hasn't been so good. So far this summer there have been many Gulf Fritillaries, occasional Zebra Heliconians and White Peacocks, and a handful of other species.

Still, as the rainiest part of the rainy season draws near, new species are appearing, such as the one at https://www.backyardnature.net/yucatan/mariposa/butt090.jpg.

That's a skipper. Skippers are a large group of fast moving, big bodied, broad headed, small winged butterflies, and we've met enough of them to know that when they're brown and long-tailed like this one, they're going to be hard to identify to species level. Volunteer identifier Bea in Ontario was due back from vacation, so I smiled thinking about welcoming her back with such a daunting challenge.

And that's the way it turned out. Bea quickly recognized the genus URBANUS, a group known generally as longtail skippers, but for getting it to species level, she knew she'd need help.

Over the years Bea has submitted many of both her and my butterfly photos to the Butterflies of America (BOA) Website at http://www.butterfliesofamerica.com/ and in the process has become friends with Mike Stangeland of the McGuire Center for Lepidoptera and Biodiversity at the Florida Museum of Natural History, University of Florida. In really hard butterfly-ID cases Bea goes to Mike. Mike wrote to Bea about our Urbanus skipper:

Mike went on to list 27 butterfly genera that are entirely or partly impossible to determine from photos, one of those 27 being our Urbanus.

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SAUCER JELLY
The other day several gelatinous, transparent discs turned up on the beach. You can see one at https://www.backyardnature.net/n/11/110828jf.jpg.

The first thought is that it's a jellyfish. However, all jellyfish I've seen are shaped like upside-down bowls, with tentacles hanging below. This was flat, and nothing hung below it.

Still, volunteer identifier Bea in Ontario and I figure that it's the remains of a jellyfish, probably the Moon Jellyfish, AURELIA AURITA. That species is common throughout most of the world's oceans, and Marcia says it's common here. Another name found for the species is Saucer Jelly (also Moon Jelly), so that sounds as if others have found such discs as ours.

I think that what we're finding here is dead Moon Jellyfish with their appendages and insides torn away by animals and/or wave action. Maybe what turns up on the beach is just the transparent cap of what once was a much handsomer, upside-down-bowl-shaped creature.

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THUNDERSTORM OUTFLOW CLOUDS
Last weekend Tropical Storm Harvey came ashore in Belize just south of us. Though the storm missed us, it got close enough to bestow us with two days and nights of blessedly cool winds and a few brief showers delivered beneath very dark, threatening-looking clouds approaching from the sea.

One interesting cloud formation associated with the hurricane developed low over the water beside and beneath bands of storms spiraling outward from Harvey's center. You can see such a low wall of dark clouds with pale, raggedy tops advancing before an approaching storm's much higher, darker clouds at https://www.backyardnature.net/n/11/110828cl.jpg.

I'm interpreting the lower clouds as being formed at the "outflow boundary" of the dark-bottomed storm looming behind them. The outflow boundary is formed like this:

Mature storms consist of both updrafts of warm air and downdrafts of much cooler air. When cool downdrafts reach ground level they spread outward. In the picture we're seeing the front of a wave of cooled "outflow" air rushing away from the center of the dark-looking storm looming behind it.

The outflow boundary also is known as a "gust front." And it's true that when the clouds reached shore they were accompanied by stiff gusts and sharply cooler air and rain.

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RAT & CAT, SEA & ME
So, there's this parasitic disease organism something like a one-celled ameba, called Toxoplasma, which infects rat brains. The problem for Toxoplasma is that in order to reproduce sexually it needs to be inside a cat's digestive system. New research has shown that Toxoplasma gets into its cat by altering its host rat's behavior toward cats; when a cat is near, instead of fleeing, either the rat gets confused, or else is actually sexually attracted to the cat. This leads to the rat being eaten by the cat, which gets the rat's Toxoplasma hitchhiker where it wants to go, which is inside the cat's gut.

Once Toxoplasma reproduces sexually in the cat's gut the microorganism now must get back into a rat's brain. It exits the cat in feces, which eventually gets eaten by a new rat, and once that new rat's brain is infected, the life cycle continues, and another cat is needed.

Research on this topic is described online at http://www.sciencedaily.com/releases/2011/08/110819141519.htm.

Isn't it something that the Universal Creative Impulse evolves such complex, devious life cycles? And that She designs brains to be vulnerable to this kind of outside manipulation? The only way I can account for it is that Nature is so tickled with diversity, with exploring every conceivable way of doing everything, that She'll kill innocent rats just so some microbes can reproduce in a very kinky fashion.

Sitting on the beach letting the implications sink in, I remember that electrodes implanted in human brains can elicit fear or pleasure, depending on where the electrodes are inserted. I remember how brain tumors, hormonal imbalances, blood pressure variations, booze and drugs can profoundly alter people's perceptions, behavior and basic personalities.

As waves wash around my feet, it occurs to me that "I" and the world around me constantly are being reinterpreted, redefined, and repositioned relative to everything else by my own body's ever-changing electrochemical status. I am an inconstant rat infected with whatever it is causing me to think this way perpetually slipping away with every interior change of ion concentration and transmembrane voltage, and I am a rat who doesn't even know what or where or why the cat is.

Still, it's clear that whatever is behind all this manifests itself not only in terms of waves and wind but also fish, flowers, clouds and birds, mountain meadows, Bach fugues, earthquakes and human thought of every kind -- or at least it's working at the illusion that these things exist -- so what's going on, whatever it is, is OK with me.

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Best wishes to all Newsletter readers,

Jim