June 21, 2015

ORIOLES BUILDING NESTS
Suddenly impressive oriole nests are appearing out in the scrub, such as the one shown inside the tall fruiting head of a Caribbean Agave at https://www.backyardnature.net/n/15/150621or.jpg.

Along the coastal road, also you see lots of nests like the one shown at https://www.backyardnature.net/n/15/150621on.jpg.

That one, instead of dangling freely as oriole nests normally do, is fairly stably wedged between the pole and the ground wire curving beneath it. In some spots along the road, every light pole for a good distance has its nest perched just like, plus other nests hang freely from wires between poles, blowing in the wind. Oriole nests have their entry holes at their tops. What appears to be an entry hole in this nest may just be a shadowy area, for it seems too small for an oriole to enter.

Seeing how large these nests were, I figured they were being made by Altamira Orioles, our largest oriole species and the one known to construct the largest nests, normally about two feet long (60cm). And that was the case when I came upon a bird working on a nest, shown at https://www.backyardnature.net/n/15/150621oo.jpg.

I read that the male follows the female while she collects nest materials, and remains nearby during nest building, incubation, and when she broods the chicks, so apparently our picture shows a female; I saw no male hanging around. In this species, the sexes are similar.

It's amazing to think about the detail of the nest-making information that must be stored in these birds' genes. The AllAboutBirds.Org website describes the Baltimore Oriole's nest-building technique, which is similar to the Altamira's. First the female hangs long fibers over the branch or wire, then pokes and darts her bill in and out of them until she tangles them. "While no knots are deliberately tied, soon the random poking has made knots and tangles, and the female brings more fibers to extend, close, and finally line the nest," the page says. Seeing the neat, tight loops anchoring the above nest to the wire, it's hard to believe that mere random poking created them.

When the above bird would finished adding a fiber, she'd immediately fly into the scrub, be gone three to five minutes, and return with another fiber. She'd rest on the wire, fiber in beak, for maybe fifteen seconds, then go to work. The nest oscillated furiously because of a strong wind that day, and the bird had to contort herself into all kinds of shapes to do her weaving. Try to figure out her leg positions in the picture at https://www.backyardnature.net/n/15/150621op.jpg.

And imagine what strain was felt with the wing way back and the tail way forward as she struggled on the gyrating nest at https://www.backyardnature.net/n/15/150621oq.jpg.

Altamira Orioles are known to take up to 26 days to finish their big nests, much longer than the temperate-zone species. Soon after these pictures were taken I returned to the area to find fewer nests than before. A big rain had come with strong wings, so maybe many fell apart or came loose from their anchoring.

*****

BLUE CRABS
Last weekend's dry-season-breaking heavy rains wrought innumerable changes in the landscape and the lives of local organisms. One change is that this week as I biked along area roads, often I met big Blue Crabs, CARDISOMA GUANHUMI. They seemed to gather at the roadside, though vehicles and my approaching bike caused them to jump back. Maybe they were thinking about crossing the road, but were afraid to do it, and with good cause, because lots of squashed crabs had left greasy splotches on the pavement. And more than one Gray Fox and feral cat had been feeding on crab remnants when they, too, were run over.

Some of these Blue Crabs were big ones. Each male bore one claw much larger than the other, and if I approached too close the crab would turn to face me and threateningly raise his big claw with the pincers open as shown at https://www.backyardnature.net/n/15/150621cr.jpg.

That male was big enough to really hurt a hand or foot, and when I got close for a picture he swung his big claw at me and waved it around. For a better perspective on just how large the claw is, you can see the above individual from above at https://www.backyardnature.net/n/15/150621cs.jpg.

At the ASnailsOdyssey.Com I read that "On a comparative basis, a crab claw exerts greater force during crushing than any force exerted in any other animal activity."

As I kept angling for a closer picture, eventually the crab moved into the mangroves for cover.

Not all Blue Crabs are blue. Some are intensely dark blue, others faded blue, and some are the color of the one shown at https://www.backyardnature.net/n/15/150621ct.jpg.

Blue Crabs collect and eat leaves and fruits close to their burrows, as well as insects and other animals, and carrion. Sometimes they eat one another. During the day they try to stay out of the sun, preferring to forage at night.

You just have to admire any crab's armor, and these Blue Crabs gave me a good look, such as the view shown at https://www.backyardnature.net/n/15/150621cu.jpg.

You wonder at all those mouthparts. At the ASnailsOdyssey.Com site I read that "the large claws ... catch, crush, and tear apart prey. From the claws the food bits are passed to 3 pairs of outer mouth appendages, the maxillipeds. These render and sort the bits, and then pass them to 2 pairs of inner appendages, the maxillae. From the maxillae the food is moved to a single pair of mandibles where, after a final maceration, it is swallowed."

In our picture, the flat, paddle-like objects in the general area where a mouth would be expected are the maxillipeds that "render and sort" bits of food, and pass the bits to the maxillae. You can't see most of the mouthparts because the maxillipeds cover them.

In that shot it's easy to make out the stalked compound eyes. Each compound eye is composed of hundreds of independent light-receiving units, or "ommatidia," each covered with a cuticular lens. Some crabs have long antennae but our Blue Crab's antenna are small, whisker-like affairs hardly visible at the inside-base of each eyestalk.

But, I didn't want to get distracted by all these exotic anatomy features. What was good this week was just seeing so many big crabs along the roads, and wondering what mysterious urge caused them to gather there so nervous about passing cars and bikers.

*****

BIG-BOTTOMED FLYING ANTS
Last weekend our dry season definitely ended with a downpour lasting much of the day, which flooded streets, dribbled through many folks' ceilings, and left standing water in many of the lagoons that for the last few weeks have been hard-baked dry. Therefore, I wasn't surprised -- in fact was delighted -- to find the large, amber-colored, waspish insect floating alive in a pool of water shown drying on my hand at https://www.backyardnature.net/n/15/150621at.jpg.

I was delighted because in much of the humid American tropics this is exactly what you look for below artificial lights -- which stood above the pool of water -- soon after the dry season's first big rain. We first met this kind of critter after the first big rain in June, when we were in upland Querétaro in 2007, where we learned that many country folks in the Americas roast and eat these insects. You can read that interesting entry at https://www.backyardnature.net/q/culonas.htm.

Then, once again in June, after the big Memorial Day rain in drought-striken southwestern Texas last year, we saw them en masse, as illustrated and described at the bottom of our Texas Leafcutter Ant Page at https://www.backyardnature.net/n/a/leaf-cut.htm.

So, yes, these are leafcutter ants, the same ants you see so often in the American tropics in long lines, with individual ants carrying cut-out leaf sections or parts of a flower, or something like that, above their heads, to be deposited in the colony's underground chamber. There a fungus will grow on the subterranean compost heap, and the ants will eat the fungus, not the compost.

But, the big, winged ant pictured on my hand isn't a leafcutter ant worker, which is what we see carrying shreds of vegetation to underground chambers. It's a drone or "male alate," very much larger than wingless, sterile worker ants. Our first big rain of the rainy season has been the signal for our local leafcutter-ant colonies to issue virgin queens and hoards of drones to mate with the queens. The queens and drones emerge at night and are attracted/distracted by artificial lights. On our Texas Leafcutter Ant Page linked to above you'll see that we were lucky enough to photograph a queen as well as a drone, and even an attempt at mating.

Seventeen leafcutter ant species of the genus Atta are recognized. The Texas species was Atta texana. The one in Querétaro in north-central Mexico had been Atta mexicana, and now here in the Yucatan we have ATTA CEPHALOTES. A map on the Internet is available showing the distribution of these species at

A close-up of our ant's head, with much-reduced mouthparts is at https://www.backyardnature.net/n/15/150621av.jpg.

For identification purposes, our Yucatan drone's wing venation was photographed, as seen at https://www.backyardnature.net/n/15/150621au.jpg.

Wikipedia offers an exceptionally good page on this species, at https://en.wikipedia.org/wiki/Atta_cephalotes.

There the mating process of the queen and drones is described: "The process starts with the queen flying up off the ground. The male will then join her and inseminate her, at which point he is no longer needed and dies."

"No longer needed and dies... " This is exactly what we have seen in several places now -- lots of dying males who have done their duty, or at least tried to, or at least wanted to very badly, and are "no longer needed," and we find them dying, en masse.

Had I not been a vegetarian, I'd have at least tried to put these drones' protein to good use, by roasting and crunching through my share of the bounty.

*****

CRUCILLO FLOWERING
After the rainy season's first rain, but a day before the deluge of last weekend and the legendary hoards of mosquitoes that followed, at the mangroves' edge it was a delight to see all the newly sprouting and flowering shrubs and small trees. It felt exactly like mid-spring days up North, except mind-numbingly hot and humid. A particularly springy-looking , head high tree or bush I hadn't seen before is shown at https://www.backyardnature.net/n/15/150621ra.jpg.

In the context of the transition zone, or "ecotone," where we were, between the mangrove and savanna/ranchland ecosystems, this plant's herbage was exceptionally dark green, lustrous and dense, so that its clusters of white flowers provided a very appealing visual contrast, as seen at https://www.backyardnature.net/n/15/150621rb.jpg.

The flowers themselves surprised me with their long tubes, which easily broke away from their subtending ovaries, which were "inferior," meaning that the flowers' sexual parts arose atop the ovaries, not below them, as you can see in a picture where a flower's animal-attracting part has broken from atop its goblet-shaped, green ovary, at https://www.backyardnature.net/n/15/150621rc.jpg.

Details seen in that photo left me scratching my bald head. Is the large, white item a corolla, or a calyx modified to look like a corolla to an animal pollinator? If it's a corolla, then where are the calyx's sepals, and what's the corolla tube doing turning green at its base? But, what plant in our area could produce inferior ovaries with such long, corolla-like calyx tubes? Breaking open the possible corolla, anthers were found attached at the tube's opening at the level of the green, oblong stigma, as shown at https://www.backyardnature.net/n/15/150621rd.jpg.

The flower's ovary looks like something in the Coffee Family, the Rubiaceae, but that would mean that the white thing is a corolla, so there must be a calyx, and this flower simply has no decent calyx.

After spending many hours trying to figure out the plant's identity I gave up and asked some friends at CICY, Yucatán state's Center for Scientific Investigation, in Mérida.

RANDIA OBCORDATA, the reply came back, meaning that the little tree/bush was indeed a member of the Coffee Family, so that the white thing was a corolla, and the calyx amounts to no more than the modest rim atop the ovaries seen in the photo. I'm used to Randia flowers having five lobes, not four as on our tree, so maybe something is going on with our tree.

Randia obcordata is fairly widely distributed in arid areas from Texas south through Mexico into southern Central America, and maybe farther. It bears no decent English name, though in Spanish it has several, including Papache Borracho, Papachillo, Altanisa and Crucillo. The latter name, Crucillo, means "Little Cross" of the Catholic kind. Down here any plant whose branches stick out at right angles is liable to be called Crucillo. Our much branching little tree's base stems do make crosses here and there, as seen at https://www.backyardnature.net/n/15/150621re.jpg.

The funny name Papache Borracho more or less means "Potato Drunk," probably referring to a feature of the fruits, which look like spherical, green apples conspicuously hanging on the stems, and which have been reported as edible, but, if more than two or three are eaten, may make you stagger like a drunk.

Five days after taking the above pictures in which the white flowers are so abundant and eye-catching, after the big rains I returned to find that not a single flower was to be seen on the tree. The tree had had its yearly moment of glory, and now was hard to spot amid all the rest of the mangroves' jungly greenery.

I'd found it and admired it just at the right moment.

*****

WOLFBERRY FLOWERING
At the edges of salt marshes sometimes a slightly succulent but otherwise woody, profusely branched bush about eight feet high (2.5m) forms very tangled masses that only a mouse could comfortably work through. During the dry season the bushes mostly lose their leaves but now not only are they issuing new leaves but also flowers. You can see the whole thing at https://www.backyardnature.net/n/15/150621lw.jpg.

Up closer you see that the leaves are tiny, and the flowers white with four, sometimes five, corolla lobes, as seen at https://www.backyardnature.net/n/15/150621lx.jpg.

In that pictures, notice how short, leaf- and flower-bearing branches along the main stem are somewhat sharply pointed. The bush bears no "real" spines, but when you stick an arm into the tangle these "spinescent branches" are spiny enough.

In the flowers, stamens number the same as the corolla lobes and bear brownish anthers that stick up from the flower's throat, surrounding a stiff style tipped with a cauliflower-like, green stigma, as shown at https://www.backyardnature.net/n/15/150621ly.jpg.

If you peep into a flower's throat, you see that the throat is hairy enough to stop most insects from entering the corolla and maybe nibbling on the precious ovary, as seen at https://www.backyardnature.net/n/15/150621lz.jpg.

We've seen this abundant bush before, last November when it very prettily bore innumerable small, red, tomato-like fruits, which you can see on its page, with more details about the plant, at https://www.backyardnature.net/yucatan/lycium.htm.

This is Wolfberry, LYCIUM CAROLINIANUM. I'd been expecting Wolfberry to produce blue to lavender flowers, because most Wolfberry flowers shown on the Internet are of those hues. However, descriptions admit that white-flowered ones exist, and now we know that we have those here.

*****

DWARF BINDWEED FLOWERING
These days when many plants are flowering after the rainy season's first rains, I'm looking especially hard for rare, narrowly endemic plants. One of the best environments in which to find such species is where the soil is very thin atop limestone bedrock. Such soils dry to a hard crust when it doesn't rain, yet next to the mangroves they may be submerged for long periods during the rainy season. Only some plant species can survive such extreme environmental conditions.

So, this week when a small, delicate-looking herbaceous plant I hadn't seen before turned up under such conditions, I was eager "to do the botany." You can see it in its rocky habitat at https://www.backyardnature.net/n/15/150621bi.jpg.

Up close the leaves looked semi-succulent, and the corollas were shaped like saucers shallowly lobed along their margins. The corollas' surfaces displayed curious "pleats" radiating from their centers, as seen at https://www.backyardnature.net/n/15/150621bk.jpg.

Five, white, pollen-filled anthers rose above each corolla's throat on slender filaments, as shown at https://www.backyardnature.net/n/15/150621bj.jpg.

When taking that picture, something funny seemed to be going on with the stamens, so I got in as close as my camera would go, and got the fuzzy image seen at https://www.backyardnature.net/n/15/150621bl.jpg.

Several slender, white items other than stamen filaments seem to be issuing from the corolla's throat. Trying to figure out what was going on, a corolla and one side of the calyx were removed to show what appears at https://www.backyardnature.net/n/15/150621bm.jpg.

There you see an oval, green ovary at the calyx's bottom, atop which two styles arise, and each style then divides again, producing four stigma-tipped styles emerging from the calyx.

Such splitting, double styles is pretty unusual, and seeing it I thought I really did have something special. However, eventually I noticed how some of the plant's stems appeared to be growing fast across the the ground's surface, and I remembered that such saucer-shaped corollas, pleating, and style shenanigans are known in the Morning Glory Family, the Convolvulaceae, so surely this was a member of that family.

In the end, the forking double styles led me easily to the genus Evolvulus, species often known as dwarf morning glories. Six Evolvulus species are listed for Ría Lagartos Biosphere Reserve.

Of those six, the one looking like ours is EVOLVULUS CONVOLVULOIDES, which goes by several English names, including Dwarf Bindweed, Purple Evolvulus, Bindweed Dwarf Morning-Glory, and variations there-on. It occurs from the southeastern US through Mexico, Central America and the Caribbean area deep into South America.

Despite it's large distribution area, it's not weedy like many morning glories. It specializes in places like where ours occured. It's very selective in where it lives.

*****

AN OBSCURE CROTON
There's a certain kind of slender, often weedy or semi-weedy herb or semi-shrub commonly found in the Yucatan. It's a scrappy looking group of plants with smallish, often stiff-hairy leaves. You can see what one looks like -- this one a bit larger and woodier than most species of the group -- in a weedy ditch along the road through the mangroves, at https://www.backyardnature.net/n/15/150621c5.jpg.

Nowadays this homely little plant draws attention to itself with modest clusters of male flowers, whose perky, white stamens show up when surrounded by nothing but greenness and shadows. A couple of flower clusters is shown at https://www.backyardnature.net/n/15/150621c6.jpg.

A closer look at the flowers, showing no hint of female parts, is at https://www.backyardnature.net/n/15/150621c7.jpg.

These flowers are very similar to flowers of others of this group. In this genus, you need to pay special attention to the vegetative parts. A leaf, broadest above its middle (obovate, a little unusual), and lobed at the base, with one lobe a little larger than the other, is shown at https://www.backyardnature.net/n/15/150621c8.jpg.

The leaf's undersurface is spectacularly white-hairy, and the short petiole bears especially long, stiff, brownish hairs, shown at https://www.backyardnature.net/n/15/150621c9.jpg.

This genus, Croton of the Euphorbia or Poinsettia Family, is so commonly encountered and distinctive that it's easy to recognize. However, figuring out which species of Croton it is, is hard. Thirty-four species are listed for the Yucatan and there just doesn't seem to be any publications to help distinguish them.

My approach to ID our bush was to use Google's advanced image-search feature, in which I restricted my internet search to pages mentioning Croton, at the "Flora de la Península de Yucatán" website, sponsored by CICY, Yucatan's Center for Scientific Investigation, in Mérida. The Flora provides information and photos on most of the Yucatan's flowering plants, and it's of great help to me. The entry page for the Flora is at http://www.cicy.mx/sitios/flora%20digital/indice_busqueda.php

Google returned hundreds of images of CICY's Croton pictures. Only a few of the species bore leaves that sometimes were wider above their middles, and only a few bore leaves with white-hairy undersurfaces, and petioles with long, brownish hairs. In fact, I could find only one species matching our pictures, and that was CROTON PERAERUGINOSUS, endemic just to the Yucatan Peninsula, but apparently fairly common within our small area.

This is a clumsy way to identify plants, but when dealing with plants from this part of the world you just have to work with what you have. I'll park our pictures here under the Google-searchable keywords "Croton peraeruginosus," and eventually an expert will stumble upon them, be glad to have them, and maybe tell me whether this time we came up with the right name.

*****

BEDS OF TURTLEGRASS
With the rains, the estuary's waters have changed drastically, often in surprising ways. One way is that in some places the water is especially clear, enabling submerged organisms to be seen better than before. A view of an aquatic plant in about a foot of water is shown at https://www.backyardnature.net/n/15/150621tt.jpg.

That's one of the four main "sea grasses" in this region, Turtlegrass, THALASSIA TESTUDINUM. As with the other sea grasses, Turtlegrass isn't really a grass -- not a member of the Grass Family. It's a monocot, like grasses, lilies, orchids and such, though, so it has flowers, which I hope someday to see.

On the Yucatan's Caribbean coast we've seen lots of Turtlegrass. There, countless tons of it washes up on beaches, as shown in our 2008 picture at https://www.backyardnature.net/yucatan/thalassi.jpg.

A close-up of its leaves' vascular structure and distinctive rounded blade-tip is at https://www.backyardnature.net/yucatan/thalassj.jpg.

In our area other sea grass species appear to contribute most to the brown masses that wash up on the Gulf's beaches. In such deposits some Turtlegrass can usually be found, and sometimes there's a lot of it -- it depends on currents, wind and other variables.

Gradually the importance of seagrass in general is being understood by the general public, as more and more property owners who "clean away the seagrass" find their beaches washing away and property threatened. Even seagrass washed up on beaches is important to local wildlife and provides a buffer to incoming waves that erode naked sand.

*****

FEATURED ESSAYS FROM THE PAST:

"Emotional Design" from the September 15, 2008 Newsletter, at https://www.backyardnature.net/n/p/080915.htm

"Ecology of A Rope Across the Road" from the June 9, 2007 Newsletter, at https://www.backyardnature.net/n/p/070609.htm

*****

Best wishes to all Newsletter readers,

Jim

All previous Newsletters are archived at https://www.backyardnature.net/n/.