April 12, 2019
DEPPE'S SQUIRREL
Last September during my camping trip into northern Guatemala's Petén Department, the first day I checked into the campground at El Rosario National Park on the west side of the town of Sayaxché, I was tickled to see squirrels scurrying about. Might these be a species new for me? In the Mexican state of Chiapas, across the Usumacinta River from the Petén, I'd already identified Red-bellied Squirrels, which you can see at https://www.backyardnature.net/q/squirrel.htm
Yucatan Squirrels also appear in the area, shown at https://www.backyardnature.net/yucatan/squ_gray.htm
Unfortunately the squirrels in El Rosario's campground were nervous creatures and last year I never did get close enough to one for a good picture. During my return visit to El Rosario a couple of weeks ago, I was determined to get a good squirrel shot.
The campground still had its squirrels, and still I couldn't get a good shot of one. They'd descend a tree on the trunk's side opposite to me, then shoot like a bullet across the open area to the next trunk, and ascend that tree again on the opposite side of the trunk. I gave up.
On my last day in the campground, on April 3rd, I passed by the park's office building, inhabited full time by several officials and works, and there on the ground about 20 feet from where the fellows liked to hang out, was a squirrel nibbling on something that one of the fellows must have tossed it. That squirrel is shown at https://www.backyardnature.net/n/19/190412sq.jpg
The squirrel's most conspicuous field mark doesn't register in the photo, because in the image you can't judge the animal's size. It was the smallest adult-looking squirrel I'd ever seen.
On the Internet, when all the eligible species for the Petén area were looked at, this squirrel's pattern of rusty and gray fur matched most closely the Deppe's Squirrel, SCIURUS DEPPEI, distributed from southern and eastern Mexico south through Central America to northern Costa Rica.
A description of Deppe's Squirrel by Troy Best, in the October, 1995 issue of Mammalian Species, published by The American Society of Mammalogists, describes the species as 343-387mm long. The Yucatan Squirrel is 450-500mm long, and the Red-bellied Squirrel is 418-573mm long.
The size and color pattern, then, indicate the Deppe's Squirrel, and there's no reason why that species should not be in El Rosario National Park. In fact, the Wikipedia page for the Deppe's Squirrel reports that in nearby Tikal National Park, populations of this species are commonly seen around the Mayan Ruins. A study of the Deppe's Squirrel population in Tikal National Park, by Lori Hiding, freely available on the Internet, documented more concentrated populations of Deppe's Squirrels around the ruins than under more natural conditions.
In general, Deppe's Squirrels eat similar foods and behave like other tree squirrels. One peculiarity of them is that females in most species of the genus Sciurus bear four pairs of mammary glands, but Deppe's Squirrels have only three pairs.
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MORE HOWLER MONKEY INFORMATION
Last week I posted pictures of Howler Monkeys seen during my recent camping trip into northern Guatemala's Petén region. Now I've had a chance to learn a bit more about them. Last week's pictures can be reviewed at https://www.backyardnature.net/chiapas/howler.htm
All howler monkey species belong to the genus Alouatta. Currently 15 howler species are recognized, all tropical American, occurring from southern Mexico south through Central America and most of northern and central South America.
The species in our pictures from lowland northern Guatemala is ALOUATTA PIGRA, in English usually known as the Guatemalan Black Howler, occurring in Mexico's southern Yucatan Peninsula, the southern Mexican states of Chiapas and Tabasco, and Belize and Guatemala's lowland Petén district. Mexico's SEMARNAT classifies the species as endangered because of habitat destruction, hunting and the capturing of individuals for the pet trade.
A 2010 study by Laura Elisa Argüello and others, conducted in the Mexican state of Tabasco -- the paper freely downloadable in Spanish -- found that during an observation period of 67 hours a small group of Guatemalan Black Howlers spent 13% of their time feeding, 13% moving about, 73% resting, and the rest of the time playing and calling.
The large percentage of resting time reflects the fact that mainly these monkeys eat leaves, much more than fruits and other items such as flowers, buds, nuts, and sometimes bird eggs; they're classified as "folivores." When they rest, microbes in their guts are busily fermenting the otherwise hard-to-digest material.
The howlers' roars or howls can be heard clearly for three miles (4.8km), apparently helping groups space themselves, as well as to claim territory, and maybe to keep others away from their mates. Mostly they howl at dawn and dusk but also occasionally throughout the day.
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PANAMA HAT PLANT
On March 31 during last month's camping trip into northern Guatemala's Petén district, in El Rosario National Park on the west side of the town of Sayaxché, I'd lost my trail through the forest and with my compass was navigating toward the highway. The compass was useful because clouds and a dense forest canopy hid the Sun. The going was rough through dense vegetation covering a very irregular, rocky limestone bedrock, so I had to watch every step or I'd blunder into a spiny palm or tumble into a sinkhole. With eyes on the forest floor, suddenly I saw the remarkable structures shown at https://www.backyardnature.net/n/19/190412cf.jpg
I'd stumbled into a whole bunch of them and in some places numerous "cones" seemed to stretch toward sunlight, as shown at https://www.backyardnature.net/n/19/190412cc.jpg
The foot-long "cones" looked like those of gymnosperms, of which pines and spruces may be the best-known members to northerners, so immediately I thought of cycads, which are palm-like gymnosperms of the tropics and subtropics. And the leaves did look like those of a palm of that group with fan-shaped leaves, as could be seen with the blades looming 10ft (3m) above the cones, at https://www.backyardnature.net/n/19/190412cd.jpg
All the blades on plants around me were deeply split and tattered looking like that one, but upon reaching the campground I found some planted ones that had received plenty of sunlight and were watered from a roof's runoff, and those leaves displayed a more systematic parting: Usually they were divided nearly to the base in four or so main divisions, with the outer margin of each main division less deeply cut. You can see the part of the blade near the petiole on one of the campground plants at https://www.backyardnature.net/n/19/190412cb.jpg
Once I began studying the situation, a problem developed with my cycad theory. On cycads, the leaves are pinnately compound, or feather-like, not palmately compound, like these. Also, no gymnosperm seems to have "cones" quite like these. And when I began looking closer at those "cones," they didn't look like gymnosperm cones at all, as evidenced by the close-up of a "cone's" surface shown at https://www.backyardnature.net/n/19/190412ce.jpg
In a gymnosperm cone, a seed is borne naked on the surface of a single scale or modified leaf, as with the papery seed of a pine cone on the single woody scale or bract below it. Our picture shows something that could be a weird seed, but either each "seed" has four scales or bracts, or none. Looking around for more mature fruiting structures, one was found that had been nibbled on by an animal, resulting in what's shown at https://www.backyardnature.net/n/19/190412cg.jpg
Cutting across a fruiting structure revealed the pretty and informative sight displayed at https://www.backyardnature.net/n/19/190412ch.jpg
At first it looks like the cross section of an ear of corn, with yellowish corn kernels. However, the yellow things aren't seeds, like corn kernels. Notice that each yellow item has inside it numerous other tiny, white items. Those white items are the seeds. The yellow, kernel-like structures are tightly crammed-together fruits resulting from the matured ovaries of many separate flowers arranged along a spiky axis. All the yellow fruits are fused together into a "multiple fruit," the nature of which is made clear by my drawing online at https://www.backyardnature.net/frt_mult.htm
All these nice details still didn't ring a bell, for these plants so commonly occurring in El Rosario National Park belong to a plant family I'd simply forgotten about. I had to "do the botany" like a Botany 101 student to realize that here was a member of the Cyclanthus Family, the Cyclanthaceae -- native only to the American tropics -- and species in that family aren't gymnosperms, but rather are monocots, like with grasses, orchids and palms.
At the university I'd learned that in an evolutionary sense the Cyclanthus Family was transitional between the palms and the Arum Family, the Araceae (Jack-in-the-pulpit), which it certainly looks like. However, now genetic sequencing has revealed that similarities to those families are only superficial. The Cyclanthus Family is closely related to the Screw-Pine Family, the Pandanceae, native to the Old World tropics, mostly Malaya and the Pacific islands. The only other member of that family we've encountered has been the Screwpine, or Pandanus, often grown in tropical gardens, shown at https://www.backyardnature.net/yucatan/pandanus.htm
In our area, several members of the Cyclanthus Family occur, but having seen the fruiting structure's anatomy so clearly it was easy to determine that what we had here was CARLODOVICA PALMATA, commonly known in English as the Panama Hat Plant. Back in the days when Panama hats were in vogue, they were made with fiber taken from this species' leaf stems, or petioles. The petioles are so slender, stiff and durable that I used them as walking sticks in rough territory. Panama Hat Plants are distributed from southern Mexico south through Central America to Peru.
Since forest animals eat the ripe fruits, I decided to take a bite myself. It was too bitter for me. I read that the fruits contain calcium oxalate crystals, which can give a sensation in the mouth of lots of small needles sticking into the flesh, but I didn't have that sensation, just the bitterness. I also read that young flowers, leaves and leafstalks as well as the rhizomes, can be eaten raw or cooked.
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SAWGRASS AROUND THE LAKE
On March 28 during last month's camping trip into northern Guatemala's Petén district, when I checked into the hillside campground in El Rosario National Park on the west side of the town of Sayaxché, I enjoyed a striking view of a more or less circular lake below the campground, and the country beyond.
The lake was very shallow and the water almost transparent. Fish easily could be seen swimming along the bottom. One of the lake's most striking features was that all around, except right below the campground, it was framed with a broad, impenetrably dense fringe of tall grasses or grasslike plants. You can see one side of the lake at https://www.backyardnature.net/n/19/190412cl.jpg
I've seen tall, dense stands of such a grasslike plant fringing bodies of water in tropical and subtropical situations -- such as in the Florida Everglades, where it's the most abundant flowering plant. It's Sawgrass, CLADIUM JAMAICENSE. Until now I've never had a chance to take a close look at a plant with mature flowers, so here was my chance, because a small cluster of flowering, 10-ft-tall (3m) Sawgrass plants grew at the lake's very edge just below the campground. You can see it at https://www.backyardnature.net/n/19/190412cm.jpg
Something to notice in that picture is that, at the plant's base, two horizontal canes shoot out bearing small tufts of leaves, which can root and form new large plants. A close-up of those tufted potential new Sawgrass plants is shown at https://www.backyardnature.net/n/19/190412cn.jpg
You can imagine that many close-together large plants all issuing such horizontal canes from which new plants arise might create an impenetrable tangle, and of course that's one thing Sawgrass is famous for, along with its blade margins bearing sharp, cutting "teeth."
The plants' large flowering heads consist of stacked, ±flat-topped clusters of spikelets, each cluster subtended by a slender bract, as shown at https://www.backyardnature.net/n/19/190412co.jpg
A single multi-branched spikelet cluster appears at https://www.backyardnature.net/n/19/190412cp.jpg
And individual spikelets show some of their unique features at https://www.backyardnature.net/n/19/190412ck.jpg
Here you don't see typical grass anatomy, because Sawgrasses aren't grasses. They belong to the Sedge Family, the Cyperaceae. In the above picture you can see that the achene-type fruits are egg-shaped, or ovoid, tipped with a sharp point, from which two or three stigmas arise, the stigmas being where pollen is received. Below each achene a brownish, papery scale arises. The scales and stigmas give the clusters an unkempt look, but Nature doesn't always find neatness adaptive and therefore desirable.
Many birds nest and feed in Sawgrass thickets, and various reptiles and amphibians find food and shelter there. The plant's seeds are abundant and nutritious. And when hurricanes comes the plants protect the shoreline from wave erosion.
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GIANT TARO FLOWERING STRUCTURE
At https://www.backyardnature.net/yucatan/e-ear.htm we look at one of several large members of the Aroid or Jack-in-the-pulpit Family, the Araceae, commonly planted as ornamentals in this area, and often known as Elephant Ears. The species on that page also often is known as Giant Taro, though it's not the Taro famous as a food source. It's Alocasia macrorrhizos.
Last March 26, as I passed through Mérida on my trip south to Guatemala, in my friend Eric's backyard I was glad to see a Giant Taro with its flowering structure intact, though the flowering period had already passed. Until now I've been unable to photograph the structure. But first, the whole plant is shown in a spot of shade in a sun-drenched garden at https://www.backyardnature.net/n/19/190412al.jpg
Giant Taro Elephant Ears is very similar to a more commonly seen Elephant Ears, Xanthosoma sagittifolium, which you can compare at https://www.backyardnature.net/yucatan/elephant.htm
One easy-to see feature separating the two species is that Giant Taro's leaves habitually point upward. Also, while petioles of its larger leaves usually attach to the blade in the usual way, on younger leaves the petioles often attach to the blade's flat surface (they're "peltate"), as shown at https://www.backyardnature.net/n/19/190412am.jpg
And now I can show you that the flowering structure of Giant Taro Elephant Ears is taller and more slender than that of the more common Elephant Ears, as you can see at https://www.backyardnature.net/n/19/190412an.jpg
Why bother with such details? Because it's simply fun to notice the differences. And Giant Taro is native to the Old World, India and thereabouts, while the more commonly seen Elephant Ears is South American.
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THE DAY THE DINOSAURS DIED
Paul in Florida sent us a link to a freely accessible, online The New Yorker article about an important new fossil excavation site in the northcentral US. The site is producing large numbers of fossils of organisms killed and preserved during the first hours of planetary destruction caused by an asteroid hitting the Earth 66 million years ago. That collision is known as the Chicxulub Impact, because ground zero for the hit was the ocean near where today the Maya town of Chicxulub exists, on the Yucatan's northwestern coast, north of Mérida.
The impact caused such environmental destruction that about 75% of all the planet's species went extinct, and more than 99.9999% of all the Earth's individual living organisms perished. In other words, Life on Earth almost ceased to exist.
This was such a mind-boggling event that I've been thinking about it this week. What is the Chicxulub Impact's teaching, I've been wondering? That question is to be expected of someone for whom "Nature is Bible," and the Chicxulub Impact was very much a natural event.
A good beginning point for thinking about the Chicxulub Impact is to let it really sink in that such events -- even more destructive ones -- are just as likely to happen today as millions of years ago. In fact, five major mass extinctions are recognized as having taken place on Earth, with the Chixculub Impact being the most recent one and not necessarily the most catastrophic. You might enjoy browsing the Geological Time Scale I've put together emphasizing and describing each major mass extinction in the context of evolving life, online at https://www.backyardnature.net/g/geo-time.htm
For me, the first teaching that came to mind was that the Creative Impulse responsible for the Universe is clearly not very concerned about the comfort and welfare of Its individual created beings, of which the Impact killed more than 99.9999% of us. It was kinder at the species level, causing only 75% extinction, since it takes only one surviving individual of such organisms as bacteria and fungi to continue the species, or two if two sexes are involved. And it's worth considering these numbers with the other number that more than 90% of all species ever evolved on Earth today are extinct.
From this teaching it's clear that we humans are on our own. No deity in the sky will shepherd us toward safety from plummeting astroids, or ourselves.
At this point in thinking about the Chixculub Impact's teaching and its implications, I couldn't overlook that right now Earth's Mass Extinction #6 is taking place, the first one caused by humans. On our Geological Time Scale page, data is referred to indicating that today the rate of human-caused extinction is occurring as much as 120,000 times faster than the background rate of extinction during all the Earth's biological history.
Knowing that this mass extinction is taking place right now almost sends me running through the streets screaming that we humans need to change our way of doing things.
But, human minds are a varied bunch and I know that the streets are populated by many minds unable or unwilling to accept the Chixculub Impact teaching I understand. For example, last week a fellow in Guatemala, remarking on the awesome destruction of the Petén's forests in recent years, told me that it's all exactly as the Bible predicts, so there's nothing we can or should do about it. Many others I know see only the economic effects of ending large-scale logging, mining, agrochemical use, etc., and for them that's reason enough for society to continue as it is. Plus there are enough of those who say it's all just false news, to democratically elect a president encouraging that opinion.
I regard these powerful subgroups of thought as nothing less than well defined species of mentality different from my own species. They're species in the sense that there's little or no exchange of genetic/mental information among them. As time passes, each group consolidates its beliefs, because its beliefs serve well within its own mental context, as long as there's still forest to cut, ore to mine, fields to spray, etc.
In Nature, different species competing for resources in the same place either change so that they begin cooperating in a sustainable fashion, or one species outcompetes the others and thus gets rid of them, or the stronger simply kill off the weaker.
Thinking, feeling people tend toward the sustainable cooperation option. However, Nature has put humanity in an interesting situation by giving those who want to keep things going as they are, a "trump" card. That card that trumps everything is the fact that when something is destroyed, it's gone for good, but when something is conserved, it still stands a good chance of being destroyed by overwhelming, never-going-away numbers of destroyers.
Therefore, I see this as a war between different species of mindsets, and from the beginning the attackers have the advantage over those trying to protect what's left.
If one is quixotic enough to want to fight for Life on Earth, anyway, how does one fight? In my own life, I can't think of any better response than to live as low-impact a life as I can, produce my nature-education website, and send out these Newsletters.
I regard these as piddling responses and wish I could do better. In fact, here's a request:
If anyone out there within busing or boating distance of where I am now can conceive of a more effectively biosphere-saving use for me, please let me know. Keep in mind that I'm a surprisingly healthy 71-year-old, but my nervous system can't function around boom-boom music and dogs barking during the night. I can live happily with no electricity, plumbing, and all the rest, though I need to be within walking or biking distance of a food-buying place. I pay my own expenses.
*****
Best wishes to all Newsletter readers,
Jim
All previous Newsletters are archived at https://www.backyardnature.net/n/.
